please check this link : 
[What is the File&#39;s Owner (in Interface builder)?][1]
[confused difference between Custom Class for an Object and for the File&#39;s Owner and steps via IB][2]

in first screen shot :  you should set the custom class of your View .

and in the second screen shot  (`files owner`) you can Set the file&#39;s owner to your UIView subclass so that you can connect outlets to it


  [1]: https://stackoverflow.com/questions/15251370/what-is-the-files-owner-in-interface-builder
  [2]: https://stackoverflow.com/questions/15150713/confused-difference-between-custom-class-for-an-object-and-for-the-files-owner

When you add custom `UIView` with `XIB` you init this custom view in some `UIViewController` and write: 

    let nib = UINib(nibName: &quot;CardView&quot;, bundle: nil)
    let view = nib.instantiate(withOwner: self, options: nil).first as! CardView

File&#39;s owner (in `withOwner:` parameter) this is usually owner is a ViewController where you add your custom 
`UIView`

 




**EDIT**: This is **not about fat arrows**. It&#39;s also not about passing _this_ to an **IIFE**. It&#39;s a transpiler-related question.

So I&#39;ve created a simple pub-sub for a little app I&#39;m working on. I wrote it in ES6 to use spread/rest and save some headaches. I set it up with npm and gulp to transpile it but it&#39;s driving me crazy.

I made it a browser library but realized it could be used anywhere so I decided to make it Commonjs and AMD compatible.

Here&#39;s a trimmed down version of my code:

    (function(root, factory) {
     if(typeof define === &#39;function&#39; &amp;&amp; define.amd) {
        define([], function() {
            return (root.simplePubSub = factory())
        });
      } else if(typeof module === &#39;object&#39; &amp;&amp; module.exports) {
        module.exports = (root.simplePubSub = factory())
      } else {
        root.simplePubSub = root.SPS = factory()
      }
    }(this, function() {
     // return SimplePubSub
    });


But no matter what I try (such as making _this_ a variable and passing it) it sets it to _undefined_.

    }(undefined, function() {

It probably has something to do with Babel not knowing what _this_ will be and transpiling it away but is there any other approach I can take?

**UPDATE**: Passing `}((window || module || {}), function() {` instead of _this_ seems to work. I&#39;m not sure this is the best approach though.

How to stop babel from transpiling &#39;this&#39; to &#39;undefined&#39; (and inserting &quot;use strict&quot;)

I am trying to create a view where I save an object but I&#39;d like to _undo_ that save if some exception is raised. This is what I tried:

    class MyView(View):
    
        @transaction.atomic
        def post(self, request, *args, **kwargs):
            try:
                some_object = SomeModel(...)
                some_object.save()
    
                if something:
                    raise exception.NotAcceptable()
                    # When the workflow comes into this condition, I think the previous save should be undone
                    # What am I missing?
    
            except exception.NotAcceptable, e:
                # do something

What am I doing wrong? even when the exception is raised `some_object` is still in Database.

Django - Rollback save with transaction atomic

In a custom xib file, what&#39;s the difference between the two following setting methods shown in the images below?
[![enter image description here][1]][1]


[![enter image description here][2]][2]


  [1]: http://i.stack.imgur.com/ziUZO.jpg
  [2]: http://i.stack.imgur.com/dKYVq.jpg

What&#39;s the difference between custom class and file&#39;s owner setting in xib file?

<p>In a custom xib file, what's the difference between the two following setting methods shown in the images below?
<a href="http://i.stack.imgur.com/ziUZO.jpg" target="_blank" rel="noopener noreferrer"><img src="http://i.stack.imgur.com/ziUZO.jpg" alt="enter image description here"></a></p>
<p><a href="http://i.stack.imgur.com/dKYVq.jpg" target="_blank" rel="noopener noreferrer"><img src="http://i.stack.imgur.com/dKYVq.jpg" alt="enter image description here"></a></p>


I am deleting some folders and files to make more space on my drive. I know that in path:

    ~/Library/Developer/CoreSimulator/Devices/

There are folders for each simulator and each version. This folder has around 11GB size for me. I know that I could delete simulators with old versions that I no longer use. But from that unique identifier I can&#39;t know which is the right one and which not. So my question is: Can I delete it all? It&#39;s okay if next time I wouldn&#39;t have any of my app in simulator but  can I loose something more? Old versions of simulator? Or anything else? Thanks

Xcode - free to clear devices folder?

I&#39;ve been experimenting with `UITextField` and how to work with it&#39;s cursor position. I&#39;ve found a number of relation Objective-C answers, as in 

- https://stackoverflow.com/questions/16432364/getting-the-cursor-position-of-uitextfield-in-ios
- https://stackoverflow.com/questions/1500233/control-cursor-position-in-uitextfield
- https://stackoverflow.com/questions/22507884/uitextfield-get-currently-edited-word

But since I am working with Swift, I wanted to learn how to get the current cursor location and also set it in Swift.

The answer below is the the result of my experimentation and translation from Objective-C.


Getting and Setting Cursor Position of UITextField and UITextView in Swift

When writing the `handler` closure of a `UIAlertAction`, should the reference to `self` be strong (the default), `weak`, or `unowned`?

There have been posts relevant to this topic ([1](https://stackoverflow.com/questions/24320347/shall-we-always-use-unowned-self-inside-closure-in-swift), [2](https://stackoverflow.com/questions/25975073/swift-closures-capturing-self-as-weak), [3](https://stackoverflow.com/questions/24042949/block-retain-cycles-in-swift), [4](https://stackoverflow.com/questions/32936264/why-specify-unowned-self-in-blocks-where-you-depend-on-self-being-there)) but I honestly don&#39;t see how they help in this case.




Let&#39;s focus on this typical code:

    func tappedQuitButton() {
        let alert = UIAlertController(title: &quot;Confirm quit&quot;, message: nil, preferredStyle: .ActionSheet)

        let quitAction = UIAlertAction(title: &quot;Quit&quot;, style: .Default) { (action) in
            self.dismissViewControllerAnimated(true, completion: nil)
        }
        alert.addAction(quitAction)

        let cancelAction = UIAlertAction(title: &quot;Cancel&quot;, style: .Default) { (action) in
            self.dismissViewControllerAnimated(true, completion: nil)
        }
        alert.addAction(cancelAction)

        presentViewController(alert, animated: true, completion: nil)
    }

This is a function inside a `UIViewController` subclass, so `self` is the view controller presenting the alert.

The [documentation](https://developer.apple.com/library/ios/documentation/Swift/Conceptual/Swift_Programming_Language/AutomaticReferenceCounting.html) says: 

&gt;Use a weak reference to avoid reference cycles whenever it is possible for that reference to have “no value” at some point in its life. If the reference will always have a value, use an unowned reference instead. 

I may be blind, but I still don&#39;t see how this helps answering my question about `UIAlertAction`. 

In the above code, is it possible for `self` to be nil _at some point in its life_? Yes. So I should mark `self` as `weak`.

But then again, I can&#39;t think of a plausible scenario where `self` will be nil when the closure is called. So as far as that closure is concerned, `self` _will always have a value_. So I should mark `self` as `unowned`. 

So, again, how should `self` be captured in a UIAlertAction&#39;s handler?

Should self be captured as strong in a UIAlertAction&#39;s handler?

I got the opposite issue from [here][1].
By default in `iOS7`, back swipe gesture of `UINavigationController`&#39;s stack could pop the presented `ViewController`. Now I just uniformed all the `self.navigationItem.leftBarButtonItem` style for all the `ViewControllers`.

Here is the code:

    self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithImage:LOADIMAGE(@&quot;back_button&quot;) style:UIBarButtonItemStylePlain target:self action:@selector(popCurrentViewController)];

after that, the `navigationController.interactivePopGestureRecognizer` is disabled. How could I make the pop gesture enabled without removing the custom `leftBarButtonItem`?

Thanks!


  [1]: https://stackoverflow.com/questions/17209468/how-to-disable-back-swipe-gesture-in-uinavigationcontroller-on-ios-7

How to enable back/left swipe gesture in UINavigationController after setting leftBarButtonItem?

I have started working with `OCMock` to write test cases for the existing project that I have integrated in my project workspace. After following all the steps mentioned in this [link][1].

When I first executed my test case it&#39;s giving the error above. I searched it and tried following some of the solutions like *creating new target*, *restarting Xcode* but it didn&#39;t help me out. Any idea?

[1]: http://ocmock.org/ios/


Test target X encountered an error (Early unexpected exit, operation never finished bootstrapping - no restart will be attempted

I downloaded the new Xcode and in Interface Builder I&#39;m having a ton of problems with warnings that say things like:

&gt; Fixed Width Constraints May Cause Clipping

It looks like this:

[![enter image description here][1]][1]

I do have localization for several languages and I understand the warning that in another language a label&#39;s size may change, but my app doesn&#39;t have this problem. I ran and tested it in Xcode 8 yesterday, it was fine. I don&#39;t want to spend hours and hours adding pointless new constraints. 

Any suggested solutions?


  [1]: https://i.stack.imgur.com/H3FpD.png

Xcode 9 - &quot;Fixed Width Constraints May Cause Clipping&quot; and Other Localization Warnings

Have been out of Swift coding for almost a year, I&#39;m back. 

Download Xcode 10 beta. Have I lost my mind?  I&#39;ve tried every trick I know, none of the UI elements show up in storyboard. Zero. The sidebar is empty. 

Xcode 10:

[![Xcode 10 Screenshot][1]][1]

Xcode 9, no problem there they are, all my UI buttons, etc.

thanks, this is kind of surreal. :-)


  [1]: https://i.stack.imgur.com/ilCZT.png

Xcode 10, where are the UI elements?

I made a pod Xcode 11 and iOS 13, created an UIScrollview and set my content there.

While installing on an older main project, this alert message shows:

&gt; Content and frame layout guides before iOS 11.0

I can see the said layout guides in Interface Builder:

[![Interface Builder layout guides][1]][1]

How can I remove them?


  [1]: https://i.stack.imgur.com/2msHA.png

Remove Content and Frame layout guides from UIScrollview

I used to use autolayout add new constraints to make simple constraints to superview / relative view like this (for loooong time): 

[![enter image description here][1]][1]

However, recently after updated to the latest xcode (11.3.3 or just 11.3/11C29), I have this weird issue: when I set the constant = 0, they always generate the constraints in an unwanted way like this: 

[![enter image description here][2]][2]

And it seems default value is somehow 20 and making my view look so wrong (0 compared to 20?)

If I fix that by edit the constraint like this:

[![enter image description here][3]][3]

Then it&#39;ll correct again (the image is after edited the constraints, before edited it display constant = `Standard`)

I don&#39;t even know how to describe the issue, but how do I fix this new `add new constraint` to use my desire point instead of standard / default?

Update:

It seems to only happened when constraint to superview. No clue how to fix tho.

Update Apr-01-2020:

Xcode11.4 fixed this.


  [1]: https://i.stack.imgur.com/H66p8.png
  [2]: https://i.stack.imgur.com/QGLh6.png
  [3]: https://i.stack.imgur.com/ajIsr.png

Xcode 11 add new constraints set zero: use set value instead of default / standard

I had a `MyViewController.swift` and a `MyViewController.xib` presenting the layout of MyViewController.

I tried different methods to load this view controller including:

 

    //1
    let myVC = UINib(nibName: &quot;MyViewController&quot;, bundle:
           nil).instantiateWithOwner(nil, options: nil)[0] as? MyViewController

    //2
    let myVC = NSBundle.mainBundle().loadNibNamed(&quot;MyViewController&quot;, owner: self, options: nil)[0] as? MyViewController

    //3
    let myVC = MyViewController(nibName: &quot;MyViewController&quot;, bundle: nil)

The third one is the only successful initialisation, but the previous two are causing error:

&gt; Terminating app due to uncaught exception &#39;NSUnknownKeyException&#39;,
&gt; 
&gt; reason: &#39;[&lt;MyApp.XXX 0x7fe8f151b4c0&gt; setValue:forUndefinedKey:]: this
&gt; class is not key value coding-compliant for the key XXX.

What&#39;s wrong with those loading methods?

Content Type	Original Author	Original Content on Stackoverflow
Question	Alfy	View Question on Stackoverflow
Solution 1 - Ios	Mo Farhand	View Answer on Stackoverflow
Solution 2 - Ios	Zhanserik	View Answer on Stackoverflow

What's the difference between custom class and file's owner setting in xib file?

Ios Problem Overview

Ios Solutions

Solution 1 - Ios

Solution 2 - Ios

Django - Rollback save with transaction atomic

How to stop babel from transpiling 'this' to 'undefined' (and inserting "use strict")

Attributions