Use this:

**Objective-C:**

    [[UIApplication sharedApplication] setIdleTimerDisabled: YES];

**Swift (legacy):**

    UIApplication.sharedApplication().idleTimerDisabled = true


**Swift 3 and above:**

    UIApplication.shared.isIdleTimerDisabled = true

Make sure to import `UIKit`.

[Here][1] is the link to the documentation from developer.apple.com.


  [1]: https://developer.apple.com/documentation/uikit/uiapplication/1623070-isidletimerdisabled

For Swift 3.0 here are two options depending on where you want to invoke the code:

**Inside AppDelegate.swift:**

`application.idleTimerDisabled = true`

**Outside AppDelegate.swift:**

`UIApplication.shared().isIdleTimerDisabled = true`

Swift 4

in AppDelegate.swift file, add the following line inside **application** function:
```
application.isIdleTimerDisabled = true
        
```
 

You can use my little lib [Insomnia][1] (Swift 3, iOS 9+) - another nice feature is that you can prevent from sleeping only when charging. 

The `idleTimerDisabled ` soultion is okay but you have to remember to set it to `false` afterwards.


  [1]: https://github.com/ochococo/Insomnia

If you have more advanced case you can use our small project: [ScreenSleepManager][1] or if it&#39;s just about particular **ViewControllers** - use [Insomnia][2] as pointed earlier. Manual dealing with `idleTimerDisabled` almost always caused me some issues (like forgot to re-set to false or handle multiple (nested) modules trying to set it).


  [1]: https://github.com/SparingSoftware/ScreenSleepManager
  [2]: https://github.com/ochococo/Insomnia

Is it possible to get division by 0 (or infinity) in the following example? 

&lt;!-- language: java --&gt;

    public double calculation(double a, double b)
    {
         if (a == b)
         {
             return 0;
         }
         else
         {
             return 2 / (a - b);
         }
    }

In normal cases it will not, of course. But what if `a` and `b` are very close, can `(a-b)` result in being `0` due to precision of the calculation?

Note that this question is for Java, but I think it will apply to most programming languages.


Is it possible to get 0 by subtracting two unequal floating point numbers?

I am writing a piece of code:

    OutputStream outputStream = new FileOutputStream(createdFile);
    GZIPOutputStream gzipOutputStream = new GZIPOutputStream(outputStream);
    BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(gzipOutputStream));

Do I need to close every stream or writer like the following?

    gzipOutputStream.close();
    bw.close();
    outputStream.close();

Or will just closing the last stream be fine?

    bw.close();


Is it necessary to close each nested OutputStream and Writer separately?

How can I prevent screen lock only when using Navigation?

Waze has the option to do that, how can I do this in my App?

How to prevent screen lock on my application with swift on iOS

<p>How can I prevent screen lock only when using Navigation?</p>
<p>Waze has the option to do that, how can I do this in my App?</p>


I&#39;ve read couple tutorials, README from @mattt but can&#39;t figure out couple things.

1. What is the proper usage of `URLRequestConvertible` in real world API? It looks like if I will create one router by implementing `URLRequestConvertible` protocol for all API - it will be barely readable. Should I create one Router per endpoint?

2. Second question most likely caused by lack of experience with Swift language. I can&#39;t figure out why `enum` is used for building router? Why we don&#39;t use class with static methods?
here is an example (from Alamofire&#39;s README)


        enum Router: URLRequestConvertible {
            static let baseURLString = &quot;http://example.com&quot;
            static let perPage = 50

            case Search(query: String, page: Int)

            // MARK: URLRequestConvertible

            var URLRequest: NSURLRequest {
                let (path: String, parameters: [String: AnyObject]?) = {
                    switch self {
                    case .Search(let query, let page) where page &gt; 1:
                        return (&quot;/search&quot;, [&quot;q&quot;: query, &quot;offset&quot;: Router.perPage * page])
                    case .Search(let query, _):
                        return (&quot;/search&quot;, [&quot;q&quot;: query])
                    }
                }()

                let URL = NSURL(string: Router.baseURLString)!
                let URLRequest = NSURLRequest(URL: URL.URLByAppendingPathComponent(path))
                let encoding = Alamofire.ParameterEncoding.URL

                return encoding.encode(URLRequest, parameters: parameters).0
            }
        }

3. There are 2 ways to pass parameters:


        case CreateUser([String: AnyObject])
        case ReadUser(String)
        case UpdateUser(String, [String: AnyObject])
        case DestroyUser(String)
and (say user has 4 parameters)

        case CreateUser(String, String, String, String)
        case ReadUser(String)
        case UpdateUser(String, String, String, String, String)
        case DestroyUser(String)
@mattt is using the first one in the example. But that will lead to &quot;hardcoding&quot; parameters&#39; names outside the router (e.g. in UIViewControllers). 
Typo in parameter name can lead to error.  
Other people are using 2nd option, but in that case it not obvious at all what each parameter represents.  
What will be the right way to do it? 

Proper usage of the Alamofire&#39;s URLRequestConvertible

It works fine with the default keyboard, but I cant get it working with the numpad.

Any ideas?

How to add &quot;Done&quot; button to Numpad in iOS using Swift?

I have the following code but my links are always blue. How do I cange the color of them?

    [_string addAttribute:NSLinkAttributeName value:tag range:NSMakeRange(position, length)];
    [_string addAttribute:NSFontAttributeName value:[UIFont fontWithName:@&quot;HelveticaNeue-Bold&quot; size:(12.0)] range:NSMakeRange(position, length)];
    [_string addAttribute:NSStrokeColorAttributeName value:[UIColor greenColor] range:NSMakeRange(position, length)];

_string is a NSMutableAttributedString and the position and length work fine.
            

    

Change the color of a link in an NSMutableAttributedString

I am defining a color in code as

    [UIColor colorWithHue:32.0/360.0 saturation:0.88 brightness:0.97 alpha:1]

If I try to set the same color in storyboard, when running the App it is a slightly different colour to the one defined in code. If I drag the color to the palate then select a different color and select the palate one again, the HSB values are slightly different. It seems it is snapping to a different (RGB?) color in interface builder.

Color in storyboard not matching UIColor

I have some custom controls I have created and I&#39;m them using in a new project. However, I keep getting errors in interface builder:

    Failed to update auto layout status: Failed to load designables from path (null)

or

    Failed to render instance of &lt;control&gt;: Failed to load designables from path (null)

I&#39;ve tested out the controls in another project and they seem to render correctly in interface builder, but I cannot get them to work in the current project. What causes this error and how might I fix it?

Thanks in advance...


Interface Builder - Failed to load designables from path (null)

I want to run a block of code in 10 seconds from an event, but I want to be able to cancel it so that if something happens before those 10 seconds, the code won&#39;t run after 10 seconds have gone by.

I&#39;ve been using this, but it&#39;s not cancellable:

    static func delay(delay:Double, closure:()-&gt;()) {
      dispatch_after(
        dispatch_time(
          DISPATCH_TIME_NOW,
          Int64(delay * Double(NSEC_PER_SEC))
        ),
        dispatch_get_main_queue(), closure
      )
    }

How can I accomplish this?

Cancel a timed event in Swift?

I would be interested in knowing how to add a calendar event in the device, but using swift. I know there are some examples made in Objective-C, but at the moment nothing in swift. Many thanks.

How to add an event in the device calendar using swift?

There&#39;s a class called `Employee`.

    class Employee {
        
        var id: Int
        var firstName: String
        var lastName: String
        var dateOfBirth: NSDate?
        
        init(id: Int, firstName: String, lastName: String) {
            self.id = id
            self.firstName = firstName
            self.lastName = lastName
        }
    }

And I have an array of `Employee` objects. What I now need is to extract the `id`s of all those objects in that array into a new array.

I also found this similar [question][1]. But it&#39;s in Objective-C so it&#39;s using `valueForKeyPath` to accomplish this.

How can I do this in Swift?


  [1]: https://stackoverflow.com/q/9890330/1077789

Get an array of property values from an object array

I have a Lambda function that’s triggered by a PUT to an S3 bucket.

I want to limit this Lambda function so that it’s only running one instance at a time – I don’t want two instances running concurrently.

I’ve had a look through the Lambda configuration and docs, but I can’t see anything obvious. I can about writing my own locking system, but it would be nice if this was already a solved problem.

**How can I limit the number of concurrent invocations of a Lambda?**

Can I limit concurrent invocations of an AWS Lambda?

C++17 introduced a new lock class called [`std::scoped_lock`](http://en.cppreference.com/w/cpp/thread/scoped_lock/scoped_lock). 

Judging from the documentation it looks similar to the already existing `std::lock_guard` class.

What&#39;s the difference and when should I use it?

std::lock_guard or std::scoped_lock?

On a Windows Server 2012 R2 system, a Kotlin program uses [`FileChannel.tryLock()`][1] to hold an exclusive lock on a file, like this:

&lt;!-- language: lang-kotlin --&gt;

    val fileRw = RandomAccessFile(file, &quot;rw&quot;)
    fileRw.channel.tryLock()

With this lock in place, I *cannot* open the file with:

 - WordPad
 - Notepad++
 - Programmatically with C#, for any value of `FileShare`:

    &lt;!-- language: lang-c# --&gt;

        using (var fileStream = new FileStream(processIdPath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
        using (var textReader = new StreamReader(fileStream))
        {
            textReader.ReadToEnd();
        }

 - From the command line, the [`type`][2] command:

    &lt;!-- language: lang-none --&gt;

        C:\some-directory&gt;type file.txt
        The process cannot access the file because another process has locked a portion of the file.

 - Internet Explorer (yes, I was desperate)

I *can* open it with Notepad.

How the heck is Notepad able to open a locked file that nothing else can?

  [1]: https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/nio/channels/FileChannel.html#tryLock()
  [2]: https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/type

Notepad beats them all?

I am facing difficulties to make it responsive according to various screen sizes. How to make it responsive?

    @override
           Widget build(BuildContext context) {
           return new Container(
           decoration: new BoxDecoration(color: Colors.white),
           child: new Stack(
            children: [
              new Padding(
                padding: const EdgeInsets.only(bottom: 350.0),
                child: new GradientAppBar(&quot; &quot;),
              ),
              new Positioned(
                bottom: 150.0,
                height: 260.0,
                left: 10.0,
                right: 10.0,
                child: new Padding(
                  padding: new EdgeInsets.all(10.0),
                  child: new Card(
                    child: new Column(
                      mainAxisSize: MainAxisSize.min,
                      children: &lt;Widget&gt;[
                        const ListTile(
                          title: const Text(
                            &#39;LOGIN&#39;,
                            textAlign: TextAlign.center,
                            style: const TextStyle(
                              fontSize: 16.50,
                              fontFamily: &quot;Helvetica&quot;,
                              fontWeight: FontWeight.bold,
                              color: Colors.black87,
                              letterSpacing: 1.00,
                            ),
                          ),
                        ),
                        new ListTile(
                          leading: const Icon(Icons.person),
                          title: new TextField(
                            controller: _user1,
                            decoration: new InputDecoration(
                                labelText: &#39;     Enter a username&#39;),
                          ),
                        ),
                        new ListTile(
                          leading: const Icon(Icons.person_pin),
                          title: new TextField(
                            controller: _pass1,
                            decoration: new InputDecoration(
                                labelText: &#39;     Enter a password&#39;),
                            obscureText: true,
                          ),
                        ),
                      ],
                    ),
                  ),
                ),
              ),
              new Positioned(
                bottom: 70.0,
                left: 15.0,
                right: 05.0,
                child: new ButtonTheme.bar(
                // make buttons use the appropriate styles for cards
                  child: new ButtonBar(
                    children: &lt;Widget&gt;[
                      new FlatButton(
                        padding: new EdgeInsets.only(right: 13.0),
                        child: new Text(
                          &#39;REGISTER HERE&#39;,
                          style: new TextStyle(
                              color: Colors.black87,
                              fontFamily: &quot;Helvetica&quot;,
                              fontSize: 15.00,
                              fontWeight: FontWeight.bold),
                        ),
                        onPressed: () {
                          Navigator.of(context).pushNamed(&#39;/facebook&#39;);
                        },
                      ),
                      new FlatButton(
                        padding: new EdgeInsets.only(right: 22.0),
                        child: new Text(
                          &#39;FORGOT PASSWORD?&#39;,
                          style: new TextStyle(
                              color: Colors.black87,
                              fontFamily: &quot;Helvetica&quot;,
                              fontSize: 15.00,
                              fontWeight: FontWeight.bold),
                        ),
                        onPressed: () {
                          Navigator.of(context).pushNamed(&#39;/Forgot&#39;);
                        },
                      ),
                    ],
                  ),
                ),
              ),
              new Positioned(
                bottom: 73.0,
                height: 180.0,
                left: 20.0,
                right: 52.0,
                child: new Padding(
                  padding: new EdgeInsets.all(0.00),
                  child: new ButtonTheme(
                    minWidth: 10.0,
                    height: 20.0,
                    padding: new EdgeInsets.only(right: 37.0),
                    child: new ButtonBar(children: &lt;Widget&gt;[
                      new CupertinoButton(
                          borderRadius:
                              const BorderRadius.all(const Radius.circular(36.0)),
                          padding: new EdgeInsets.only(left: 70.0),
                          color: const Color(0xFF426DB7),
                          child: new Text(
                            &quot;     LOGIN                            &quot;,
                            style: new TextStyle(
                                color: Colors.white,
                                fontSize: 12.50,
                                fontFamily: &quot;Handwriting&quot;,
                                fontWeight: FontWeight.w500,
                                letterSpacing: 0.00),
                          ),
                          onPressed: () {})
                    ]),
                  ),
                ),
              ),
            ],
          ),
        );
      }
    }

How to make flutter app responsive according to different screen size?

I&#39;m implementing an authentication flow in my Flutter app.

After a sign in attempt, the CheckAuth *(which checks whether a user is signed in or not and then opens home screen or sign up screen accordingly)* is opened with this code: 

      void _signIn() async {
        await _auth
            .signInWithEmailAndPassword(
                email: _userEmail.trim(), password: _userPassword.trim())
            .then((task) {
          // go to home screen
          if (task.getIdToken() != null) {
            setState(() {
              Navigator.pushReplacement(
                  context,
                  new MaterialPageRoute(
                      builder: (BuildContext context) =&gt; new CheckAuth()));
            });
          } else {
            print(&quot;Authentication failed&quot;);
          }
        });
      }


Problem: I can successfully sign in to the app, but if I tap back button after I sign in, it goes back to the sign in screen (while I expect it to exit from the app).

Question: **How to move from one screen to another in Flutter without the way back?** 

Do I need to somehow delete the navigator history? Or don&#39;t use navigator at all? I tried *Navigator.replace* method, but it didn&#39;t seem to work.

Content Type	Original Author	Original Content on Stackoverflow
Question	alvarogalia	View Question on Stackoverflow
Solution 1 - Ios	atwalsh	View Answer on Stackoverflow
Solution 2 - Ios	Crashalot	View Answer on Stackoverflow
Solution 3 - Ios	kavehmb	View Answer on Stackoverflow
Solution 4 - Ios	nsmeme	View Answer on Stackoverflow
Solution 5 - Ios	Dev_IL	View Answer on Stackoverflow

How to prevent screen lock on my application with swift on iOS

Ios Problem Overview

Ios Solutions

Solution 1 - Ios

Solution 2 - Ios

Solution 3 - Ios

Solution 4 - Ios

Solution 5 - Ios

Is it necessary to close each nested OutputStream and Writer separately?

Is it possible to get 0 by subtracting two unequal floating point numbers?

Attributions