Does anyone know the best way to check to see if an optional protocol method has been implemented.

I tried this:

    if ([self.delegate respondsToSelector:@selector(optionalProtocolMethod:)] )

where delegate is:

    id&lt;MyProtocol&gt; delegate;

	

However, I get an error saying that the function `respondsToSelector:` is not found in the protocol!




Checking to see if an optional protocol method has been implemented

What is difference between https protocol and SSL Certificate that we use in web browser?

Aren&#39;t both of these used to encrypt communication between client (browser) and server?

Difference between https protocol and SSL Certificate

I have a made a protocol in my VC in which i&#39;m getting the location placemark from one my my swift file class. In my swift class i have declare the protocol like this,

     weak var delegate: HandleMapSearch?
But the xcode is showing me error `&#39;weak&#39; must not be applied to non-class-bound &#39;HandleMapSearch&#39;; consider adding a protocol conformance that has a class bound` . It was working fine before but now when i run the app it shows this error. What is this for and how can i remove this error? This is how i have created protocol in my VC class. 

    protocol HandleMapSearch {
    func dropPinZoomIn(placemark:MKPlacemark)
    }

Weak&#39; must not be applied to non-class-bound consider adding a protocol conformance that has a class bound

Is there a way to define some kind of handling mechanism in Android **and** iOS that would allow me to do intercept either of the following:

    myapp:///events/3/
    - or -
    http://myapp.com/events/3/

I&#39;d like to &#39;listen&#39; for either the protocol or the host, and open a corresponding Activity / ViewController.

I&#39;d like too if these could be as system wide as possible. I imagine this will be more of an issue on iOS, but I&#39;d ideally be able to click either of those two schemes, as hyperlinks, from any app. Gmail, Safari, etc.


Android / iOS - Custom URI / Protocol Handling

I have seen:

  - `http://www...`
  - `ftp://blah.blah...`
  - `file://blah.blah...`
  - `unreal://blah.blah...`
  - `mailto://blah.blah...`

What is that first section where you see `http` and the like called?

Can I register my own?


How do I create my own URL protocol? (e.g. so://...)

I read about _Pragma_ header on [Wikipedia](http://en.wikipedia.org/wiki/List_of_HTTP_header_fields) which says:

&gt; &quot;The Pragma: no-cache header field is an HTTP/1.0 header intended for
&gt; use in requests. It is a means for the browser to tell the server and
&gt; any intermediate caches that it wants a fresh version of the resource,
&gt; not for the server to tell the browser not to cache the resource. Some
&gt; user agents do pay attention to this header in responses, but the
&gt; HTTP/1.1 RFC specifically warns against relying on this behavior.&quot;

But I haven&#39;t understood what it does? What is the difference between the `Cache-Control` header whose value is `no-cache` and `Pragma` whose value is also `no-cache`?

Difference between Pragma and Cache-Control headers?

What is the difference between TCP and UDP? 

I know that TCP is used in the case of non-time critical applications, and UDP is used for games or applications that require fast transmission of data. I know that TCP is used for HTTP, HTTPs, FTP, SMTP, and Telnet. I know that UDP is used for DNS and DHCP.

But why? What characteristics of TCP and UDP make it useful for their respective use cases? 

Difference between TCP and UDP?

I&#39;m trying to understand clojure protocols and what problem they are supposed to solve. Does anyone have a clear explanation of the whats and whys of clojure protocols?

Simple explanation of clojure protocols

How do I register a custom protocol with Windows so that when clicking a link in an email or on a web page my application is opened and the parameters from the URL are passed to it?

How do I register a custom URL protocol in Windows?

does anyone have a good definition for what a binary protocol is? and what is a text protocol actually? how do these compare to each other in terms of bits sent on the wire? 

here&#39;s what wikipedia says about binary protocols:

A binary protocol is a protocol which is intended or expected to be read by a machine rather than a human being (http://en.wikipedia.org/wiki/Binary_protocol)

oh come on! 

to be more clear, if I have jpg file how would that be sent through a binary protocol and how through a text one? in terms of bits/bytes sent on the wire of course. 

at the end of the day if you look at a string it is itself an array of bytes so the distinction between the 2 protocols should rest on what actual data is being sent on the wire. in other words, on how the initial data (jpg file) is encoded before being sent.



binary protocols v. text protocols

There are a lot of topics about the [HTTP/2][1] protocol, but I wonder if there is a working website with this protocol.

I.e.

We can decide to use `http://` or `https://`, but how can we write a HTTP/2 request?

I am aware that this protocol depends on the server capability, but I can not find a way to check if a website, e.g. `google.com`, has HTTP/2 support enabled.

[![HTTP/2 browser support][2]][2]

As I can see in this picture, all modern browsers support this protocol.
I have not seen any link that could look like a new generation protocol.

Are we using the HTTP/2 protocol without knowing or it is just a fairy tale?

  [1]: https://en.wikipedia.org/wiki/HTTP/2
  [2]: https://i.stack.imgur.com/pyhyL.png


How to check if a website has HTTP/2 protocol support

I have an object (a UIViewController) which may or may not conform to a protocol I&#39;ve defined.

I know I can determine if the object conforms to the protocol, then safely call the method:

    if([self.myViewController conformsToProtocol:@protocol(MyProtocol)]) {
        [self.myViewController protocolMethod]; // &lt;-- warning here
    }


However, XCode shows a warning:

    warning &#39;UIViewController&#39; may not respond to &#39;-protocolMethod&#39;

What&#39;s the right way to prevent this warning?  I can&#39;t seem to cast `self.myViewController` as a `MyProtocol` class.

Cast an instance of a class to a @protocol in Objective-C

I&#39;m coding a p2p implementation that I would like to make decentralized however I&#39;m having some trouble grasping how DHT in protocols like bittorrent work. How does the client know where the peers are if there is no tracker? Are peers stored in the actual torrent file?

How does DHT in torrents work?

I want this protocol:

    protocol AddsMoreCommands {
         /* ... */
    }

only to be adopted by classes that inherit from the class `UIViewController`. [This page][1] tells me I can specify that it is only adopted by a class (as opposed to a struct) by writing

    protocol AddsMoreCommands: class {
    }
but I cannot see how to require that it is only adopted by a particular class. [That page later][1] talks about adding `where` clauses to protocol extensions to check conformance but I cannot see how to adapt that either.

    extension AddsMoreCommands where /* what */ {
    }

Is there a way to do this?
Thanks!

  [1]: https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Protocols.html#//apple_ref/doc/uid/TP40014097-CH25-ID267

How to require that a protocol can only be adopted by a specific class

I  have a category on NSDate and it would be convenient if it could implement a protocol I previously created. Is this possible? what&#39;s the correct syntax for this?

Can a category implement a protocol in Objective C?

What&#39;s the difference between DTR/DSR and RTS/CTS hardware flow control? When is each one used? Why do we need more than one kind of hardware flow control? :)

What is the difference between DTR/DSR and RTS/CTS flow control?

 - How can I send and receive messages on the server side using WebSocket, as per the protocol?

 - Why do I get seemingly random bytes at the server when I send data from the browser to the server? It the data encoded somehow?

 - How does the framing work in both the server &amp;rarr; client and client &amp;rarr; server directions?


How can I send and receive WebSocket messages on the server side?

I have created a custom URL protocol handler.

`http://`

`mailto://`

**`custom://`**

I have registered a WinForms application to respond accordingly. This all works great.

But I would like to be able to gracefully handle the case where the user doesn&#39;t have the custom URL protocol handler installed, yet.

In order to be able to do this I need to be able to detect the browser&#39;s registered protocol handlers, I would assume from JavaScript. But I have been unable to find a way to poll for the information. I am hoping to find a solution to this problem.

Thanks for any ideas you might be able to share.





How to detect browser&#39;s protocol handlers?

I have a protocol P that returns a copy of the object:

    protocol P {
        func copy() -&gt; Self
    }

and a class C that implements P:

    class C : P {
        func copy() -&gt; Self {
            return C()
        }
    }

However, whether I put the return value as `Self` I get the following error: 

&gt; Cannot convert return expression of type &#39;C&#39; to return type &#39;Self&#39;

I also tried returning `C`.  


    class C : P {
        func copy() -&gt; C  {
            return C()
        }
    }

That resulted in the following error: 
&gt; Method &#39;copy()&#39; in non-final class &#39;C&#39; must return `Self` to conform
&gt; to protocol &#39;P&#39;

Nothing works except for the case where I prefix `class C` with `final` ie do: 

    final class C : P {
        func copy() -&gt; C  {
            return C()
        }
    }


However if I want to subclass C then nothing would work. Is there any way around this?

Protocol func returning Self

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

I have a doubt about protocols in Swift about the use of **var** and the **keywords { get set }**.

From [Apple documentation][1]:

&gt; If a protocol requires a property to be gettable and settable, that
&gt; property requirement cannot be fulfilled by a constant stored property
&gt; or a read-only computed property. If the protocol only requires a
&gt; property to be gettable, the requirement can be satisfied by any kind
&gt; of property, and it is valid for the property to be also settable if
&gt; this is useful for your own code.
&gt; 
&gt; Property requirements are always declared as variable properties,
&gt; prefixed with the var keyword. Gettable and settable properties are
&gt; indicated by writing { get set } after their type declaration, and
&gt; gettable properties are indicated by writing { get }.

I can&#39;t understand why I can&#39;t use **let**. A **var** in a protocol with only **get** isn&#39;t just a **let**?

Something like this:

    protocol someProtocol 
    {
       var someProperty: String { get }
    }

it would not be just:

    protocol someProtocol 
    {
       let someProperty: String
    }

I&#39;m missing something?

  [1]: https://developer.apple.com/library/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Protocols.html

Why I can&#39;t use let in protocol in Swift?

What&#39;s the difference between Protocols and class-bound Protocols, and which one we should use in Swift?

    protocol A : class { ... }
    
    protocol A { ... }

We get an error when attempting to add a `weak` delegate when the Protocol is not defined as `: class`:

    protocol A { ... }

    weak var delegate: A

Gives the error:

 &gt; &#39;weak&#39; cannot be applied to non-class type
 
 or 

 &gt; &#39;weak&#39; must not be applied to non-class-bound &#39;A&#39;; consider adding a protocol conformance that has a class bound

Swift protocol error: &#39;weak&#39; cannot be applied to non-class type

Both this declaration

    protocol SomeProtocol : AnyObject {
    }

and this declaration

    protocol SomeProtocol : class {
    }

seem to make it so that only classes can conform to this protocol (i.e. that the instances of the protocol are references to objects), and have no other effects.

Is there any difference between them? Should one be preferred over the other? If not, why is there two ways to do the same thing?

I am using the latest released Xcode 6.3.1.

What&#39;s the difference between a protocol extended from AnyObject and a class-only protocol?

I just came across this strange thing I got to see  application is that by default they use `SOCK_STREAM` function.  Why is it so? Is this `SOCK_STREAM` just creating multiple streams? Or is it the standard `SOCK_STREAM` function available for creating TCP stream(s)? 

I thought tsunami is based on UDP, but still having some features like that of TCP, e.g. TCP fairness, friendlyness, etc. 

Could somebody please shed some light on this issue? I am totally confused over this.


What is SOCK_DGRAM and SOCK_STREAM?

I&#39;m implementing a *very* custom NavigationLink called `MenuItem` and would like to reuse it across the project. It&#39;s a struct that conforms to `View` and implements `var body : some View` which contains a `NavigationLink`.
I need to somehow store the view that shall be presented by `NavigationLink` in the body of `MenuItem` but have yet failed to do so.

I have defined `destinationView` in `MenuItem`&#39;s body as `some View` and tried two initializers:

This seemed too easy:
```Swift
struct MenuItem: View {
    private var destinationView: some View
    
    init(destinationView: View) {
        self.destinationView = destinationView
    }

    var body : some View {
        // Here I&#39;m passing destinationView to NavigationLink...
    }
}
```
**--&gt; Error:** Protocol &#39;View&#39; can only be used as a generic constraint because it has Self or associated type requirements.

2nd try:
```Swift
struct MenuItem: View {
    private var destinationView: some View
    
    init&lt;V&gt;(destinationView: V) where V: View {
        self.destinationView = destinationView
    }

    var body : some View {
        // Here I&#39;m passing destinationView to NavigationLink...
    }
}
```
**--&gt; Error:** Cannot assign value of type &#39;V&#39; to type &#39;some View&#39;.

Final try:
```Swift
struct MenuItem: View {
    private var destinationView: some View
    
    init&lt;V&gt;(destinationView: V) where V: View {
        self.destinationView = destinationView as View
    }

    var body : some View {
        // Here I&#39;m passing destinationView to NavigationLink...
    }
}
```

**--&gt; Error:** Cannot assign value of type &#39;View&#39; to type &#39;some View&#39;.

I hope someone can help me. There must be a way if NavigationLink can accept some View as an argument.
Thanks ;D

How to pass one SwiftUI View as a variable to another View struct

I am eager to know about the architecture of different real-time messenger apps. Are they using any generic protocol/architecture?

What is the technology behind wechat, whatsapp and other messenger apps?

When I try to implement my protocol this way:

    protocol Serialization {
        func init(key keyValue: String, jsonValue: String)
    }

I get an error saying: **Expected identifier in function declaration.** 

Why am I getting this error?

Can I have an init func in a protocol?

I am looking for a tutorial/blog post on how to implement bittorrent protocol step by step.
How it works? How do you make requests to peers? and talk to trackers.

I do not mind the programming language (java,ruby,perl,c#)

Implementing Bittorrent Protocol

I need to extract the full protocol, domain, and port from a given URL. For example:

    https://localhost:8181/ContactUs-1.0/contact?lang=it&amp;report_type=consumer
    &gt;&gt;&gt;
    https://localhost:8181

Get protocol, domain, and port from URL

What are the pros and cons of each of them?    
Where should I use them specifically?

NSNotificationCenter vs delegation( using protocols )?

I often hear things like &quot;Can we load our employee info using LDAP?&quot;  Yet, the title &quot;Lightweight Directory Access Protocol&quot; makes me think of it as a protocol rather than a physical database management system like Oracle or MSSQL.

So could someone please explain to me what LDAP is, how it&#39;s used, and how it basically works?  Is LDAP simply a standard protocol for extracting data from a variety of DBMSs?  In an architecture diagram, would LDAP be simply an arrow drawn between the DB and the application server?

Could someone please explain LDAP?

I don&#39;t think this can be done but I&#39;ll ask anyway. I have a protocol:

    protocol X {}

And a class:
  
    class Y:X {}

In the rest of my code I refer to everything using the protocol X. In that code I would like to be able to do something like:

    let a:X = ...
    let b:X = ...
    if a == b {...}

The problem is that if I try to implement `Equatable`:

    protocol X: Equatable {}
    func ==(lhs:X, rhs:X) -&gt; Bool {
        if let l = lhs as? Y, let r = hrs as? Y {
            return l.something == r.something
        }
        return false
    } 

The idea to try and allow the use of `==` whilst hiding the implementations behind the protocol.

Swift doesn&#39;t like this though because `Equatable` has `Self` references and it will no longer allow me to use it as a type. Only as a generic argument.
   

So has anyone found a way to apply an operator to a protocol without the protocol becoming unusable as a type?

Swift Equatable on a protocol

I’m trying to mix generics with protocols and I’m getting a really hard time xD

I have certain architecture implemented in an Android/Java project, and I’m trying to rewrite it to fit it in a swift/iOS project. But I’ve found this limitation.

**ProtocolA**

    protocol ProtocolA {
        
    }

**ProtocolB**

    protocol ProtocolB : ProtocolA {
        
    }

**ImplementProtocolA**

    class ImplementProtocolA &lt;P : ProtocolA&gt; {
        
        let currentProtocol : P
        
        init(currentProtocol : P) {
            self.currentProtocol = currentProtocol
        }
      
    }

**ImplementProtocolB**

    class ImplementProtocolB : ImplementProtocolA&lt;ProtocolB&gt; {
        
    }

So, when I try to set *ProtocolB* as the concrete type that implements *ProtocolA*, I get this error:

***Using &#39;ProtocolB&#39; as a concrete type conforming to protocol &#39;ProtocolA&#39; is not supported***

1 Is there any reason for this “limitation”?

2 Is there any workaround to get this implemented?

3 Will it be supported at some point?

  
**--UPDATED--**

*Another variant of the same problem, I think:* 

**View protocols**

    protocol View {
    
    }

    protocol GetUserView : View {
        func showProgress()
        func hideProgress()
        func showError(message:String)
        func showUser(userDemo:UserDemo)
    }

**Presenter protocols**

    protocol Presenter {
        typealias V : View
    }
    
    class UserDemoPresenter : Presenter {
        typealias V = GetUserView
    }

***Error:*** 

&gt; UserDemoPresenter.swift Possibly intended match &#39;V&#39; (aka
&gt; &#39;GetUserView&#39;) does not conform to &#39;View’

What is that?? It conforms!

Even if I use View instead of GetUserView, it does not compile.

    class UserDemoPresenter : Presenter {
        typealias V = View
    }

&gt; UserDemoPresenter.swift Possibly intended match &#39;V&#39; (aka &#39;View&#39;) does
&gt; not conform to &#39;View&#39; 


xxDD I don’t get it, really.  

**--UPDATED--**

With the solution proposed by Rob Napier the problem is not fixed, instead, it is just delayed.

When a try to define a reference to UserDemoPresenter, I need to specify the generic type, so I get the same error:

    private var presenter : UserDemoPresenter&lt;GetUserView&gt;

&gt; Using &#39;GetUserView&#39; as a concrete type conforming to protocol
&gt; &#39;GetUserView&#39; is not supported

Using some protocol as a concrete type conforming to another protocol is not supported

I need a simple communication protocol between two devices (a PC and a microcontroller). The PC must send some commands and parameters to the micro. The micro must transmit an array of bytes (data from sensor).

The data must be [noise protected][1] (besides parity checking, I think I need some other data correction method).

Is there any standard solution to do this? (I need only an idea, not the complete solution).

P.S. Any advice is appreciated. *P.P.S Sorry for any grammar mistakes, I hope you understand.*

**Edit 1.** I have not decided whether it will be ***master/slave*** protocol or both sides can initiate communication. The PC must know when micro have done a job and can send data. It can continuously poll the micro if data is ready, or the micro can send data, when a job is done. I don&#39;t know which is better and simpler.

**Edit 2.** ***Hardware and [physical layer][2] protocol.*** Since [RS-232][3]C serial standard used in the PC, I will use [asynchronous communication][4]. I will use only RxD, TxD and GND signals. I can&#39;t use additional wires because the microcontroller AFAIK doesn&#39;t support them. BTW I&#39;m using the [AVR][5] ATmega128 chip.

So I will use fixed baud rate, 8 bits of data, 2 stop bits without parity checking (or with?).

***[Data link protocol][6]***. That&#39;s what my question primarily concerned about. Thanks for suggesting [HDLC][7], [PPP][8] and [Modbus][9] protocols. I will research on it.


  [1]: http://en.wikipedia.org/wiki/Error_detection_and_correction
  [2]: http://en.wikipedia.org/wiki/Physical_Layer
  [3]: http://en.wikipedia.org/wiki/RS-232
  [4]: http://en.wikipedia.org/wiki/Asynchronous_serial_communication
  [5]: http://en.wikipedia.org/wiki/Atmel_AVR
  [6]: http://en.wikipedia.org/wiki/Data_Link_Layer
  [7]: http://en.wikipedia.org/wiki/High-Level_Data_Link_Control
  [8]: http://en.wikipedia.org/wiki/Point-to-Point_Protocol
  [9]: http://en.wikipedia.org/wiki/Modbus

Simple serial point-to-point communication protocol

I have two `view controllers A` and `B`, and they both have each other as their delegates.

When I did nothing except define the protocols at the beginning of the header files and `#import` the other&#39;s header file, I got two errors along the lines of -

&gt; cannot find protocol declaration for &quot;BDelegate&quot;, which was showing in
&gt; A.h (where I wrote &lt;BDelegate&gt;) cannot find protocol declaration for
&gt; &quot;ADelegate&quot;, which was showing in B.h (where I wrote  &lt;ADelegate&gt;)


Looking online, people had written earlier that the circular inclusion of header files could be leading to the problems. They recommended either using `#include` instead, or `@class` declaration like -

    @class A

instead of

    #import A.h

inside `#import B.h`

I have tried almost every combination of these imports, and `@classes`, and `#include` but still can&#39;t get rid of the warnings. Also, solutions online recommended moving the `#import` to the `.m` files but that didn&#39;t help either. Part of the reason is that the solutions online are kinda fuzzy - if you could break it down that would be great.

Any suggestions about what can be done to fix this?


--------------------------------------------------
**-- BigViewController.h --**

    
    #import &quot;BaseViewController.h&quot;
    #include &quot;BaseViewController.h&quot;
    
    @class BigViewController;
    
    @protocol BigViewControllerDelegate
    -(void) BigViewController:(BigViewController *) bigView;
    @end
    
    @interface BigViewController : UIViewController &lt;BaseViewControllerDelegate&gt;
    {    
         //delegate
         id &lt;BigViewControllerDelegate&gt; delegate;
    
    ivars...	
    }
    
    @properties...
    @end
    
    --------------------------------------------------
    
**-- BaseViewController.h --**

    #&lt;UIKit/UIKit.h&gt;
    
    #import &quot;BigViewController.h&quot;
    #include &quot;BigViewController.h&quot;
    
    @class BigViewController;
    
    @protocol BaseViewControllerDelegate
    - (void) setParametersWithItemChosen:(Item *) item;
    @end
    
    @interface BaseViewController : UIViewController &lt;...BigViewControllerDelegate...&gt;
    {
    
       ivars...
    
       //delegate
        id &lt;BaseViewControllerDelegate&gt; delegate;
    }
    
    @properties...
    @end
    




Cannot find protocol declaration

    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?

Does anyone know of a good tool to generate Google Protobuf documentation using the .proto source files?


Generate Protobuf documentation?

There are four common protocols for network access of SVN.

    svn://repos
    svn+ssh://repos
    https://repos
    http://repos

The Wikipedia page doesn&#39;t say much about the differences of the four different protocols. I&#39;ve always preferred `svn://`, because it is the easiest to set up, but what is the difference and which one is &quot;better&quot;?


Which protocol? svn:// or http(s)://?

Is there a reason we include the `http` / `https` protocol on the `href` attribute of links?

Would it be fine to just leave it off:

    &lt;a href=&quot;example.com&quot;&gt;my site&lt;/a&gt;

html - links without http protocol

*ObjectProperties.h*

    @protocol ObjectProperties &lt;NSObject&gt;
    
    @property (strong, nonatomic) NSString *name;
    @property (strong, nonatomic) NSDate *date;
    @property (assign, nonatomic) int64_t index;
    
    @end

*ClassA.h*

    #import &lt;Foundation/Foundation.h&gt;
    
    @protocol ObjectProperties;
    
    @interface ClassA : NSObject &lt;ObjectProperties&gt;
    
    - (void)specialSauce;
    
    @end;

*ManagedClassA.h*

    #import &lt;CoreData/CoreData.h&gt;
    
    @protocol ObjectProperties;
    
    @interface ManagedClassA : NSManagedObject &lt;ObjectProperties&gt;
    
    - (void)doSomething;
    
    @end;


From the code example above, I have defined a protocol in a .h file to be used with both Core Data objects as well as plain ol&#39; vanilla objects. It seems like &quot;noise&quot; to have conforming classes ‪#import‬ the protocol in the their header; it would be cleaner to forward declare the protocol &amp; import‬ in the implementation file as I&#39;ve shown above. However, Xcode throws a warning when doing it this way:

`Cannot find protocol definition for &#39;ObjectProperties&#39;`

The code compiles, and mostly works. I say mostly because there&#39;s some funkiness with Core Data trying to dynamically create the getters / setters for the scalar property, but I think that&#39;s probably because I&#39;ve hit an edge case.

Of course, the most obvious work around is to just import the protocol header into the class headers.

If my understanding is correct (and my knowledge is very recently acquired, and so it&#39;s entirely possible that I&#39;m wrong), if I import the protocol into my class headers and make a change to the protocol, then all subsequent files that import my classes will have to be recompiled.

What is the correct way to do solve this type of problem?

Objective-C Protocol Forward Declarations

What is the difference between a `protocol` and a `delegate`?

and,

How can we declare `variables` in a `protocol class`?

All Protocols Solutions on Gang of Coders

Total of 41 Protocols Solutions