What&#39;s the proper way to use for-in loop with an optional?

Right now I always perform an optional binding before looping it.  Are there other idioms?


    let optionalInt:[Int]? = [1, 2, 3]
            
    if let optionalInt = optionalInt {
      for i in optionalInt {
        print(i)
      }
    }



Swift: How to use for-in loop with an optional?

If you have protocol like so:

    protocol Messaging {
        func sendMessage(message: String)
    }

Is there any way to satisfy it in a class like so:

    class Messager: Messaging {
        func sendMessage(message: String, count: Int = 1) {}
    }

This would be nice to have, as the resulting signature of the protocol is satisfied by adding the defaulted parameter. Is there any way to get this to work with Swift 2?

This is a simplified example. Let&#39;s say, for the sake of argument, that the protocol is fixed. A solution can only update the Messager class. My goal is to be able to call `sendMessage()` like so:

    let m: Messaging = Messager()
    m.sendMessage(&quot;&quot;)

The only way I found to accomplish this (and satisfy the compiler) is with overloading like so:

    class Messager: Messaging {
        func sendMessage(message: String) {
            self.sendMessage(message, count: 1)
        }

        func sendMessage(message: String, count: Int = 1) {}
    }

The problem with this approach is that my defaults are then specified in two places and I lose the main advantage of Swift&#39;s default parameters.

Is it possible to satisfy Swift protocol and add defaulted arguments?

I&#39;m using some external codes from google in my new Swift 2.0 project that required &quot;libz.dylib&quot; in earlier versions. After updating to the new Xcode / the new SDK.

Xcode is now unable to import the libz.dylib and throws some errors 

&gt; Undefined symbols for architecture i386:
  &quot;_deflate&quot;, referenced from:
      +[GAICompressionUtil gai_dataByCompressingBytes:length:compressionLevel:mode:] in libGoogleAnalyticsServices.a(GAICompressionUtil.o)
  &quot;_deflateEnd&quot;, referenced from:
      +[GAICompressionUtil gai_dataByCompressingBytes:length:compressionLevel:mode:] in libGoogleAnalyticsServices.a(GAICompressionUtil.o)
  &quot;_deflateInit2_&quot;, referenced from:
      +[GAICompressionUtil gai_dataByCompressingBytes:length:compressionLevel:mode:] in libGoogleAnalyticsServices.a(GAICompressionUtil.o)
  &quot;_inflate&quot;, referenced from:
      +[GAICompressionUtil gai_dataByInflatingBytes:length:isRawData:] in libGoogleAnalyticsServices.a(GAICompressionUtil.o)
  &quot;_inflateEnd&quot;, referenced from:
      +[GAICompressionUtil gai_dataByInflatingBytes:length:isRawData:] in libGoogleAnalyticsServices.a(GAICompressionUtil.o)
  &quot;_inflateInit2_&quot;, referenced from:
      +[GAICompressionUtil gai_dataByInflatingBytes:length:isRawData:] in libGoogleAnalyticsServices.a(GAICompressionUtil.o)
ld: symbol(s) not found for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)

When looking through the available packages in the &quot;build phase&quot; settings I can find &quot;libz.tbd&quot; which seems to be the replacement for the libz.dylib. When importing this lib the linker error stays the same but I get this additional warning:

&gt; warning: skipping file &#39;/Applications/Xcode-beta.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator9.0.sdk/usr/lib/libz.tbd&#39; (unexpected file type &#39;text&#39; in Frameworks &amp; Libraries build phase)

What to do?


Swift 2 / iOS 9 - libz.dylib not found

I have found a few questions regarding this issue, yet none of them were helping with my problem. I am trying to save an object to core data using this code (which worked perfectly fine in Xcode 6 and Simulator...):

    let fetchRequest = NSFetchRequest(entityName: &quot;Patient&quot;)
    let fetchedResults : [NSManagedObject]!
    do {
        fetchedResults = try managedContext.executeFetchRequest(fetchRequest) as! [NSManagedObject]
        patienten = fetchedResults
    }    catch {
        print(&quot;error&quot;)
    }

I added the do-try-catch once I started working on this project in the Xcode 7 beta and a physical device. 
Now, when I hit the Save button, this piece of code is called, the app freezes and I get the following: 

&gt;warning: could not load any Objective-C class information from the dyld shared cache. This will significantly reduce the quality of type information available.

[![Screenshot][1]][1]

Does anybody know where I went wrong?


  [1]: https://i.stack.imgur.com/uXFX1.png

Swift 2, warning: could not load any Objective-C class information from the dyld shared cache

I&#39;m trying to run my iOS app that was migrated from `Swift 1.2` to `Swift 2.0` in Xcode 7 using iPhone Simulator (any), I&#39;m getting the following error:

&gt; The operation couldn’t be completed. (FBSOpenApplicationErrorDomain
&gt; error 1.)

I already tried to reset simulator settings and content, quit Xcode, clean project, etc.

FBSOpenApplicationErrorDomain error 1

I have a Package.swift in my project like:

    import PackageDescription
    
    let package = Package(
        name: &quot;ProjectName&quot;,
            dependencies: [
               .Package(url: &quot;https://github.com/example/repo.git&quot;, majorVersion: 0)
            ]
     )

When I run `swift build` I get errors like… 


    /project/Packages/WebViewController.swift:1:8: error: no such module &#39;UIKit&#39;
    import UIKit
           ^

Where should I tell the swift package manager where to find UIKit?

Swift Package Manager - UIKit Dependency

I am trying to create a dictionary extension where Dictionary is of the type &amp;lt;String, AnyObject&amp;gt;.

Was looking in many places and trying different approaches, but none of them seemed to work. This was one of them:

    extension Dictionary where &lt;String, AnyObject&gt;{
        var jsonString:String {
            return &quot;&quot;
        }
    }


**Another method that didn&#39;t actually work for some reason:**

    extension Dictionary where Key:Hashable, Value:AnyObject {
    
        var jsonString:String {

            do {
               let stringData = try NSJSONSerialization.dataWithJSONObject(self, options: NSJSONWritingOptions.PrettyPrinted)
                if let string = String(data: stringData, encoding: NSUTF8StringEncoding){
                    return string
                }
            }catch _ {
            
            }
            return &quot;&quot;
        }
    }

Got: **Argument type &#39;Dictionary&lt;Key,Value&gt;&#39; does not conform to expected type of &#39;AnyObject&#39;**

extension of Dictionary where &lt;String, AnyObject&gt;

I need to get a UIImage only instead of loading a normal UIImageView with [Kingfisher library][1] 

To realize it I implemented a workaround with UIImageView:

    let imageView = UIImageView()

    imageView.kf_setImageWithURL(NSURL(string: cpa.imageName)!, placeholderImage: nil,
            optionsInfo: [.Transition(ImageTransition.Fade(1))],
            progressBlock: { receivedSize, totalSize in
                print(&quot;\(receivedSize)/\(totalSize)&quot;)
            },
            completionHandler: { image, error, cacheType, imageURL in
                anView!.image = image //anView IS NOT an UIImageView
                anView!.frame.size = CGSize(width: 15.0, height: 15.0)
                print(&quot;Finished&quot;)
        })

This code works perfectly, but I would like to do it in a cleaner way.
Is there a method in this library to get an UIImage only? Async and cached


  [1]: https://github.com/onevcat/Kingfisher

Get UIImage only with Kingfisher library

Swift 2 introduced the `guard` keyword, which could be used to ensure that various data is configured ready to go. An example I saw on [this website][1] demonstrates an submitTapped function:

    func submitTapped() {
        guard username.text.characters.count &gt; 0 else {
            return
        }
    
        print(&quot;All good&quot;)
    }
I am wondering if using `guard` is any different than doing it the old fashioned way, using an `if` condition. Does it give benefits, which you could not get by using a simple check?

  [1]: http://www.hackingwithswift.com/swift2

Swift&#39;s guard keyword

Getting this error in Swift 2.0.

&gt; Binary operator &#39;|&#39; cannot be applied to two UIViewAutoresizing operands

Here is the code:

    let view = UIView(frame: CGRect(x: 0, y: 0, width: 320, height: 568))
    addSubview(view)
    view.autoresizingMask = UIViewAutoresizing.FlexibleWidth | UIViewAutoresizing.FlexibleHeight

Any idea what can be the problem?
![enter image description here][1]


  [1]: http://i.stack.imgur.com/xVzxK.png

Binary operator &#39;|&#39; cannot be applied to two UIViewAutoresizing operands

I am trying to register my application for local notifications this way:

    UIApplication.sharedApplication().registerUserNotificationSettings(UIUserNotificationSettings(forTypes: UIUserNotificationType.Alert | UIUserNotificationType.Badge, categories: nil))

In Xcode 7 and Swift 2.0 - I get error `Binary Operator &quot;|&quot; cannot be applied to two UIUserNotificationType operands`. Please help me.

Swift 2.0 - Binary Operator &quot;|&quot; cannot be applied to two UIUserNotificationType operands

In [Swift 2.0][1], Apple introduced a new way to handle errors (do-try-catch).
And few days ago in Beta 6 an even newer keyword was introduced (`try?`).
Also, knew that I can use `try!`.
What&#39;s the difference between the 3 keywords, and when to use each?

  [1]: http://ahmedabdurrahman.com/2015/08/22/swift-2-0/

try, try! &amp; try? what’s the difference, and when to use each?

I have been reading about Optionals in Swift, and I have seen examples where `if let` is used to check if an Optional holds a value, and in case it does – do something with the unwrapped value.

However, I have seen that in Swift 2.0 the keyword `guard let` is used mostly. I wonder whether `if let` has been removed from Swift 2.0 or if it still possible to be used.

Should I change my programs that contain `if let` to `guard let`?

Swift: guard let vs if let

I give it a try to understand new error handling thing in swift 2. Here is what I did: I first declared an error enum:

    enum SandwichError: ErrorType {
        case NotMe
        case DoItYourself
    }

And then I declared a method that throws an error (not an exception folks. It is an error.). Here is that method:

    func makeMeSandwich(names: [String: String]) throws -&gt; String {
        guard let sandwich = names[&quot;sandwich&quot;] else {
            throw SandwichError.NotMe
        }
        
        return sandwich
    }

The problem is from the calling side. Here is the code that calls this method:

    let kitchen = [&quot;sandwich&quot;: &quot;ready&quot;, &quot;breakfeast&quot;: &quot;not ready&quot;]

    do {
        let sandwich = try makeMeSandwich(kitchen)
        print(&quot;i eat it \(sandwich)&quot;)
    } catch SandwichError.NotMe {
        print(&quot;Not me error&quot;)
    } catch SandwichError.DoItYourself {
        print(&quot;do it error&quot;)
    }

After the `do` line compiler says `Errors thrown from here are not handled because the enclosing catch is not exhaustive`. But in my opinion it is exhaustive because there is only two case in `SandwichError` enum. 

For regular switch statements swift can understands it is exhaustive when every case handled.

Swift do-try-catch syntax

I tend to only put the necessities (stored properties, initializers) into my class definitions and move everything else into their own `extension`, kind of like an `extension` per logical block that I would group with `// MARK:` as well.

For a UIView subclass for example, I would end up with an extension for layout-related stuff, one for subscribing and handling events and so forth. In these extensions, I inevitably have to override some UIKit methods, e.g. `layoutSubviews`. I never noticed any issues with this approach -- until today.

Take this class hierarchy for example:

    public class C: NSObject {
        public func method() { print(&quot;C&quot;) }
    }
    
    public class B: C {
    }
    extension B {
        override public func method() { print(&quot;B&quot;) }
    }
    
    public class A: B {
    }
    extension A {
        override public func method() { print(&quot;A&quot;) }
    }

    (A() as A).method()
    (A() as B).method()
    (A() as C).method()

The output is `A B C`. That makes little sense to me. I read about Protocol Extensions being statically dispatched, but this ain&#39;t a protocol. This is a regular class, and I expect method calls to be dynamically dispatched at runtime. Clearly the call on `C` should at least be dynamically dispatched and produce `C`?

If I remove the inheritance from `NSObject` and make `C` a root class, the compiler complains saying `declarations in extensions cannot override yet`, which I read about already. But how does having `NSObject` as a root class change things?

Moving both overrides into their class declaration produces `A A A` as expected, moving only `B`&#39;s produces `A B B`, moving only `A`&#39;s produces `C B C`, the last of which makes absolutely no sense to me: not even the one statically typed to `A` produces the `A`-output any more!

Adding the `dynamic` keyword to the definition or an override does seem to give me the desired behavior &#39;from that point in the class hierarchy downwards&#39;...

Let&#39;s change our example to something a little less constructed, what actually made me post this question:

    public class B: UIView {
    }
    extension B {
        override public func layoutSubviews() { print(&quot;B&quot;) }
    }
    
    public class A: B {
    }
    extension A {
        override public func layoutSubviews() { print(&quot;A&quot;) }
    }
    
    
    (A() as A).layoutSubviews()
    (A() as B).layoutSubviews()
    (A() as UIView).layoutSubviews()

We now get `A B A`. Here I cannot make UIView&#39;s layoutSubviews dynamic by any means.

Moving both overrides into their class declaration gets us `A A A` again, only A&#39;s or only B&#39;s still gets us `A B A`. `dynamic` again solves my problems.

In theory I could add `dynamic` to all `override`s I ever do but I feel like I&#39;m doing something else wrong here.

Is it really wrong to use `extension`s for grouping code like I do?

Overriding methods in Swift extensions

I am looking at Xcode 7.3 notes and I notice this issue.

&gt; The ++ and -- operators have been deprecated

Could some one explain why it is deprecated? And am I right that in new version of Xcode now you going to use instead of `++` this `x += 1`;

Example:

    for var index = 0; index &lt; 3; index += 1 {
        print(&quot;index is \(index)&quot;)
    }

[![Screenshot for warning][1]][1]


  [1]: http://i.stack.imgur.com/3DUjN.png

The &quot;++&quot; and &quot;--&quot; operators have been deprecated Xcode 7.3

I have a protocol RequestType and it has associatedType Model as below.

    public protocol RequestType: class {
    
        associatedtype Model
        var path: String { get set }
           
    }

    public extension RequestType {
        
        public func executeRequest(completionHandler: Result&lt;Model, NSError&gt; -&gt; Void) {
            request.response(rootKeyPath: rootKeyPath) { [weak self] (response: Response&lt;Model, NSError&gt;) -&gt; Void in
                completionHandler(response.result)
                guard let weakSelf = self else { return }
                if weakSelf.logging { debugPrint(response) }
            }
        }
        
    }

Now I am trying to make a queue of all failed requests.

    public class RequestEventuallyQueue {
        
        static let requestEventuallyQueue = RequestEventuallyQueue()
        let queue = [RequestType]()
        
    }

But I get the error on line `let queue = [RequestType]()` that Protocol RequestType can only be used as a generic constraint because it has Self or associatedType requirements.


Protocol can only be used as a generic constraint because it has Self or associatedType requirements

So I can do this:

    var stringNumb: NSString = &quot;1357&quot;

    var someNumb: CInt = stringNumb.intValue

But I can&#39;t find the way to do it w/ a `String`.  I&#39;d like to do something like:

    var stringNumb: String = &quot;1357&quot;

    var someNumb: Int = Int(stringNumb)

This doesn&#39;t work either:

    var someNumbAlt: Int = myString.integerValue

Get integer value from string in swift

My app shares photo on Instagram, to do this it first saves it on a temporary directory:

    let writePath = NSTemporaryDirectory().stringByAppendingPathComponent(&quot;instagram.igo&quot;)

It was working on `Swift 1.2`, but does not work on `Swift 2.0`.

Given error message is: 
&gt;stringByAppendingPathComponent is unavailable: use URLByAppendingPathComponent on NSURL instead.

stringByAppendingPathComponent is unavailable

In swift 2.0, `print()` automatically adds a newline character. In swift 1.2, `println()` and `print()` used to be separate functions. So how do I print some text and not add a newline to it since swift no longer has a print function that does not append newlines. 


print without newline in swift

I know this topic is quite popular, but I&#39;m a little iniciate problem in a programming language, the fact is that I still do not understand where I put the code. Well, I&#39;ll tell the whole case:

[![enter image description here][1]][1]

I&#39;m trying to make a modal Swift in a little different from normal: By clicking on a button, the ViewController is displayed (following modal type) on the screen, but with transparent background. Only the blue View with label will be displayed. When this ViewController is presented, it is with transparent background, but as soon as it completes the transition, it will stay with the black background. Already deactivated the opaque option, and tested some options, but nothing this troubleshooting.

Some can help me?

The video is a test in the simulator on the case (https://www.youtube.com/watch?v=wT8Uwmq9yqY).


  [1]: http://i.stack.imgur.com/DGFlN.png

I&#39;m starting with swift, and I&#39;m still pretty lost with how to program in Xcode, I read an answer to a question that has the following code to solve this:

    self.presentingViewController.providesPresentationContextTransitionStyle = YES;
    self.presentingViewController.definesPresentationContext = YES;
    modal.modalPresentationStyle = UIModalPresentationOverCurrentContext;

Where do I put this code?

Swift Modal View Controller with transparent background

I want to remove a key-value pair from a dictionary like in the example.

    var dict: Dictionary&lt;String,String&gt; = [:]
    //Assuming dictionary is added some data.
    var willRemoveKey = &quot;SomeKey&quot;
    dict.removePair(willRemoveKey) //that&#39;s what I need




How to remove a key-value pair from swift dictionary?

I am using presentViewController to present new screen 

    let dashboardWorkout = DashboardWorkoutViewController()
    presentViewController(dashboardWorkout, animated: true, completion: nil)

This presents new screen from bottom to top but I want it to presented from right to left without using `UINavigationController`. 

I am using Xib instead of storyboard so how can I do that ?

How to present view controller from right to left in iOS using Swift

I&#39;m updating my code to use Swift, and I&#39;m wondering how to print error details for an exception that matches the &#39;catch all&#39; clause.  I&#39;ve slightly modified the example from this [Swift Language Guide Page][1] to illustrate my point:

    do {
        try vend(itemNamed: &quot;Candy Bar&quot;)
        // Enjoy delicious snack
    } catch VendingMachineError.InvalidSelection {
        print(&quot;Invalid Selection.&quot;)
    } catch VendingMachineError.OutOfStock {
        print(&quot;Out of Stock.&quot;)
    } catch VendingMachineError.InsufficientFunds(let amountRequired) {
        print(&quot;Insufficient funds. Please insert an additional $\(amountRequired).&quot;)
    } catch {
        // HOW DO I PRINT OUT INFORMATION ABOUT THE ERROR HERE?
    }

If I catch an unexpected exception, I need to be able to log something about what caused it.


  [1]: https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/ErrorHandling.html

How to print details of a &#39;catch all&#39; exception in Swift?

I&#39;m wondering if it&#39;s possible to achieve such a thing.  
I have a Playground like this:

    protocol Foo {
        func testPrint()
    }
    
    extension Foo {
        func testPrint() {
            print(&quot;Protocol extension call&quot;)
        }
    }
    
    struct Bar: Foo {
        func testPrint() {
            // Calling self or super go call default implementation
            self.testPrint()
            print(&quot;Call from struct&quot;)
        }
    }
    
    
    let sth = Bar()
    sth.testPrint()

I can provide a default implementation in `extension` but what if `Bar` needs everything that is in default implementation plus additional things?  
It&#39;s somehow similar to calling `super.` methods in `class`es to fulfill requirement of implementing every property etc. but I see no possibility to achieve the same with `structs`.

Calling protocol default implementation from regular method

After I update my Firebase via &quot;pod update&quot;, I got error like this :

    ld: warning: directory not found for option &#39;-F/Users/bennysantoso/Library/Developer/Xcode/DerivedData/FCM-atfcxuircoryufazlomgwfgmvaqm/Build/Products/Debug-iphonesimulator/GoogleToolboxForMac&#39;
    ld: framework not found GoogleToolboxForMac
    clang: error: linker command failed with exit code 1 (use -v to see invocation)

Here my Podfile :

    # Uncomment this line to define a global platform for your project
    # platform :ios, &#39;9.0&#39;
    pod &#39;Firebase/Core&#39;
    pod &#39;Firebase/Messaging&#39;

    target &#39;BB&#39; do
      # Comment this line if you&#39;re not using Swift and don&#39;t want to use dynamic frameworks
      use_frameworks!

      # Pods for BB

      target &#39;BBTests&#39; do
        inherit! :search_paths
        # Pods for testing
      end

      target &#39;BBUITests&#39; do
        inherit! :search_paths
        # Pods for testing
      end

    end

Does anybody know about this error?

I seek out relationships GoogleToolboxForMac and Firebase, but I just get a little bit of information.

FYI, I use Swift 2.3 and Firebase 3.8.0.

I will be grateful for any help you can provide. Thanks!

Framework not found GoogleToolboxForMac

When passing a class or primitive type into a function, any change made in the function to the parameter will be reflected outside of the class. This is basically the same thing an `inout` parameter is supposed to do.

What is a good use case for an inout parameter?  

When to use inout parameters?

I am using AFNetworking in my iOS app and for all the GET requests it makes, I build the url from a base URL and than add parameters using NSDictionary Key-Value pairs.

The problem is that I need same key for different values.

Here is an example of what I need the finally URL to look like -

http://example.com/.....&amp;id=21212&amp;id=21212&amp;id=33232

It&#39;s not possible in NSDictionary to have different values in same keys. So I tried NSSet but did not work.

    let productIDSet: Set = [prodIDArray]
    let paramDict = NSMutableDictionary()
    paramDict.setObject(productIDSet, forKey: &quot;id&quot;)


How can I build a URL with query parameters containing multiple values for the same key in Swift?

I&#39;d like to use the Accelerate framework to extend [Float] and [Double] but each of these requires a different implementation.

I tried the obvious:

    extension Array&lt;Float&gt; {
    }

and get this error:

&gt; &quot;Constrained extension must be declared on the unspecialised generic
&gt; type &#39;Array&#39; with constraints specified by a &#39;where&#39; clause&quot;

Is it posible to extend generic types in Swift 2 in this way?


I&#39;ve got the code working as expected now.  Here&#39;s an example showing a summation using the Accelerate framework.

    extension _ArrayType where Generator.Element == Float {
        
        func quickSum() -&gt; Float {
            var result: Float = 0
            if var x = self as? [Float] {
                vDSP_sve(&amp;x, 1, &amp;result, vDSP_Length(x.count))
            }
            return result
        }
    }

    extension _ArrayType where Generator.Element == Double {
        
        func quickSum() -&gt; Double {
            var result: Double = 0
            if var x = self as? [Double] {
                vDSP_sveD(&amp;x, 1, &amp;result, vDSP_Length(x.count))
            }
            return result
        }
    }

Extend array types using where clause in Swift

Is it possible to use Swift 2.2 in Xcode 8? 

From Xcode 8 release notes: 

&gt; &quot;Xcode 8 supports switching toolchains, such as those from swift.org,
&gt; without relaunching Xcode. (23135507)&quot;

I have been trying to find swift 2.2 toolchain on swift.org website but couldn&#39;t. Have any one success in configuring Xcode 8 to work with swift 2.2

Use Swift 2.2 in Xcode 8?

Let&#39;s say I want to split a string by an empty space. This code snippet works fine in Swift 1.x. It does not work in Swift 2 in Xcode 7 Beta 1.

    var str = &quot;Hello Bob&quot;
    var foo = split(str) {$0 == &quot; &quot;}

I get the following compiler error:

    Cannot invoke &#39;split&#39; with an argument list of type &#39;(String, (_) -&gt; _)

Anyone know how to call this correctly?

**Updated**: Added a note that this was for the Xcode 7 beta 1.

Using the split function in Swift 2

    class SomeClass {
      var someProperty: Int {
        throw Err(&quot;SNAFU&quot;)
      }
    }

For code like the above, the swift binary complains &#39;error is not handled because the enclosing function is not declared &#39;throws&#39;.

How do I declare that &#39;someProperty&#39; &#39;throws&#39; in the above?

    class SomeClass {
      var someProperty throws: Int {
      }
    }

and

    class SomeClass {
      var someProperty: throws Int {
      }
    }

and
    
    class SomeClass {
      var someProperty: Int throws {
      }
    }

don&#39;t seem to work.

How do I declare that a computed property &#39;throws&#39; in Swift?

I just noticed that `static` members of Swift `structs` are implicitly `lazy`. 

For instance, this will only call the `init` once:

    class Baz {
        init(){
            print(&quot;initializing a Baz&quot;)
        }
    }
    struct Foo {
        static let bar = Baz()
    }
    
    var z = Foo.bar
    z = Foo.bar

What&#39;s the rationale behind this?

What if I want the opposite behaviour?

Implicitly lazy static members in Swift

I was using this, in Swift 1.2

    let urlwithPercentEscapes = myurlstring.stringByAddingPercentEscapesUsingEncoding(NSUTF8StringEncoding)

This now gives me a warning asking me to use

    stringByAddingPercentEncodingWithAllowedCharacters

I need to use a **NSCharacterSet** as an argument, but there are so many and I cannot determine what one will give me the same outcome as the previously used method.

**An example URL I want to use will be like this**

    http://www.mapquestapi.com/geocoding/v1/batch?key=YOUR_KEY_HERE&amp;callback=renderBatch&amp;location=Pottsville,PA&amp;location=Red Lion&amp;location=19036&amp;location=1090 N Charlotte St, Lancaster, PA

The URL Character Set for encoding seems to contain sets the trim my
URL. i.e, 
&gt; 
&gt; The path component of a URL is the component immediately following the
&gt; host component (if present). It ends wherever the query or fragment
&gt; component begins. For example, in the URL
&gt; http://www.example.com/index.php?key1=value1, the path component is
&gt; /index.php.

However I don&#39;t want to trim any aspect of it.
When I used my String, for example `myurlstring` it would fail.

But when used the following, then there were no issues. It encoded the string with some magic and I could get my URL data.

    let urlwithPercentEscapes = myurlstring.stringByAddingPercentEscapesUsingEncoding(NSUTF8StringEncoding)

As it

&gt; Returns a representation of the String using a given encoding to
&gt; determine the percent escapes necessary to convert the String into a
&gt; legal URL string

Thanks

How to use stringByAddingPercentEncodingWithAllowedCharacters() for a URL in Swift 2.0

Is there any *built-in* way to create an ordered map in Swift 2? Arrays `[T]` are sorted by the order that objects are appended to it, but dictionaries `[K : V]` aren&#39;t ordered.

For example

    var myArray: [String] = []
    myArray.append(&quot;val1&quot;)
    myArray.append(&quot;val2&quot;)
    myArray.append(&quot;val3&quot;)

    //will always print &quot;val1, val2, val3&quot;
    print(myArray)


    var myDictionary: [String : String] = [:]
    myDictionary[&quot;key1&quot;] = &quot;val1&quot;
    myDictionary[&quot;key2&quot;] = &quot;val2&quot;
    myDictionary[&quot;key3&quot;] = &quot;val3&quot;
   
    //Will print &quot;[key1: val1, key3: val3, key2: val2]&quot;
    //instead of &quot;[key1: val1, key2: val2, key3: val3]&quot;
    print(myDictionary)
    
Are there any built-in ways to create an ordered `key : value` map that is ordered in the same way that an array is, or will I have to create my own class? 

I would like to avoid creating my own class if at all possible, because whatever is included by Swift would most likely be more efficient.

Ordered map in Swift

I converted an NSIndexSet to an [Int] array using the answer at https://stackoverflow.com/a/28964059/6481734 I need to do essentially the opposite, turning the same kind of array back into an NSIndexSet.

Create NSIndexSet from integer array in Swift

    protocol Car {
         var wheels : Int { get set}
    
         init(wheels: Int)
    
    }
    
    extension Car {
        init(wheels: Int) {
            self.wheels = wheels
        }
    }

on self.wheels = wheels i get the error

    Error: variable &#39;self&#39; passed by reference before being initialized


How can I define the initializer in the protocol extension?

How to define initializers in a protocol extension?

I&#39;m experimenting with Swift protocol extensions and I found this quite confusing behaviour. Could you help me how to get the result I want?

See the comments on the last 4 lines of the code. (You can copy paste it to Xcode7 playground if you want). Thank you!!

    protocol Color { }
    extension Color {  var color : String { return &quot;Default color&quot; } }
    
    protocol RedColor: Color { }
    extension RedColor { var color : String { return &quot;Red color&quot; } }
    
    
    protocol PrintColor {
        
         func getColor() -&gt; String
    }
    
    extension PrintColor where Self: Color {
        
        func getColor() -&gt; String {
            
            return color
        }
    }
    
    
    class A: Color, PrintColor { }
    class B: A, RedColor { }
    
    
    let colorA = A().color // is &quot;Default color&quot; - OK
    let colorB = B().color // is &quot;Red color&quot; - OK
    
    
    let a = A().getColor() // is &quot;Default color&quot; - OK
    let b = B().getColor() // is &quot;Default color&quot; BUT I want it to be &quot;Red color&quot;

Swift Protocol Extensions overriding

I was working on an application that used a text field and translated it into an integer. Previously my code 

    textField.text.toInt() 

worked. Now Swift declares this as an error and is telling me to do

    textField.text!.toInt()
and it says there is no `toInt()` and to try using `Int()`. That doesn&#39;t work either. What just happened?

.toInt() removed in Swift 2?

Let&#39;s say there are two arrays...

    var array1 = [&quot;a&quot;, &quot;b&quot;, &quot;c&quot;]
    var array2 = [&quot;b&quot;, &quot;c&quot;, &quot;a&quot;]

I&#39;d like the result of the comparison of these two arrays to be true, and the following...

    var array1 = [&quot;a&quot;, &quot;b&quot;, &quot;c&quot;]
    var array2 = [&quot;b&quot;, &quot;c&quot;, &quot;a&quot;, &quot;d&quot;]

...to be false. How can I achieve that in Swift? I tried to convert both arrays to sets but for some reason Set() keeps removing some (usually duplicated) objects that the array contains.

Any help would be appreciated.

How do I check in Swift if two arrays contain the same elements regardless of the order in which those elements appear in?

In Swift 2.0 `NSError` conforms to the `ErrorType` protocol.

For a customly defined error, we can specify the associating object(s) for some cases, like below.

    enum LifeError: ErrorType {
        case BeBorn
        case LostJob(job: String)
        case GetCaughtByWife(wife: String)
        ...
    }

We can comfortably do the following:

    do {
        try haveAffairWith(otherPerson)
    } catch LifeError.GetCaughtByWife(let wife) {
        ...
    }
    
However if we want it to pass into other places as an `NSError`, it loses its associating object information.

    println(&quot;\(LifeError.GetCaughtByWife(&quot;Name&quot;) as NSError)&quot;)

prints:

    Error Domain=... Code=1 &quot;The operation couldn&#39;t be completed&quot;. (... error 1)

and its `userInfo` is `nil`.

Where is my `wife` associated with the `ErrorType`?

All Swift2 Solutions on Gang of Coders

Total of 41 Swift2 Solutions