CODEWITHSUNDEEP
iosnslogautolayout
user1046037
user1046037

Reputation: 17685

iOS AutoLayout - get frame size width

I am developing using iOS 6 auto layout

I would like to log a message displaying the frame width of the view.

I can see the textView on the screen.

But I get the width and height as zero, am I missing something ?

NSLog(@"textView    = %p", self.textView);
NSLog(@"height      = %f", self.textView.frame.size.height);
NSLog(@"width       = %f", self.textView.frame.size.width);

textView    = 0x882de00
height      = 0.000000
width       = 0.000000

Upvotes: 59

Views: 71011

Answers (9)

Johnhappily
Johnhappily

Reputation: 1

I agree with the solution of "user1046037"

If you are using both atuoLayout guides, and code at the same time, you would better to put frame(or NSlayoutConstraints) programming into "ViewDidAppear", especially when you are designing UI for multiple devices.

Based on my tests, iOS14 will take autoLayouts from screen(default iPhone 11 Pro Max) before "ViewDidLoad", and update it in "ViewDidAppear".

For people who are not familiar with view cycle, its "load view from storyboard" -> "ViewDidLoad" -> "ViewWillAppear" -> "ViewDidAppear".

Upvotes: 0

Bhavesh Patel
Bhavesh Patel

Reputation: 596

You can only find out the size after the first layout pass. Or Just call below method then after you got actual width of you view.

[yourView layoutIfNeeded];

Upvotes: 3

SamSol
SamSol

Reputation: 2881

This is really strange feature. But I found:

If you want to get frame without using layoutsubviews method, Use this one:

dispatch_async(dispatch_get_main_queue(), ^{
        NSLog(@"View frame: %@", NSStringFromCGRect(view.frame));
    });

This is really strange!!!

Upvotes: 10

Echelon
Echelon

Reputation: 7922

None of the above answers worked completely for me, except viewDidLoad but that has the side effect of not displaying what I want until after the view has animated in, which looks poor.

viewDidLayoutSubviews should be the correct place to run code that relies on the autolayout being complete, but as others have pointed out it is called multiple times in recent iOS versions and you can't know which is the final call.

So I resolved this with a small hack. In my storyboard, mySubview should be smaller than its containing self.view. But when viewDidLayoutSubviews is first called, mySubview still has a width of 600, whereas self.view seems to be set correctly (this is an iPhone project). So all I have to do is monitor subsequent calls and check the relative widths. Once mySubview is smaller than self.view I can be sure it has been laid out correctly. 

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()

    if self.mySubview.bounds.size.width < self.view.bounds.size.width {

        // mySubview's width became less than the view's width, so it is
        // safe to assume it is now laid out correctly...

    }
}

This has the advantage of not relying on hard-coded numbers, so it can work on all iPhone form factors, for example. Of course it may not be a panacea in all cases or on all devices, but there are probably many ingenious ways to do similar checks of relative sizes.

And no, we shouldn't have to do this, but until Apple gives us some more reliable callbacks, we're all stuck with it.

Upvotes: 7

Francescu
Francescu

Reputation: 17054

Actually I managed to force the layout update before my code within the viewDidLoad:

override func viewDidLoad() {
        super.viewDidLoad()

        println("bounds before \(self.previewContainer.bounds)");
        //on iPhone 6 plus -> prints bounds before (0.0,0.0,320.0,320.0)

        self.view.setNeedsLayout()
        self.view.layoutIfNeeded()

        println("bounds after \(self.previewContainer.bounds)");
        //on iPhone 6 plus -> prints bounds after (0.0,0.0,414.0,414.0)

        //Size dependent code works here
        self.create()
    }

UPDATE: This doesn't seem to work anymore

Upvotes: 13

diegosantiviago
diegosantiviago

Reputation: 1078

Include in your viewDidLoad()

self.view.setNeedsLayout()
self.view.layoutIfNeeded()

Before accessing yourview.frame.size.width

Upvotes: 35

Jesper
Jesper

Reputation: 7605

I think auto layout hasn't had the time to layout your views by the time you call this. Auto layout hasn't happened by the time viewDidLoad is called, because it's called just after the views are loaded and it's only after that that the views are placed into the view controller's view hierarchy and eventually laid out (in the view's layoutSubviews method).

Edit: this answer points out why the scenario in the question doesn't work. @dreamzor's answer points out where to place your code in order to solve it.

Upvotes: 59

dreamzor
dreamzor

Reputation: 5925

Actually, above answers are not quite right. I followed them and got zeros again and again.

The trick is to place your frame-dependent code to the viewDidLayoutSubviews method, which

Notifies the view controller that its view just laid out its subviews.

Do not forget that this method is called multiple times and is not the part of ViewController's life cycle, so be careful while using this.

Hope it will be helpful to someone.

Just wanted to add, that for my program without landscape mode NOT using Auto Layout is way much simplier... I tried, though =D

Upvotes: 156

user1046037
user1046037

Reputation: 17685

Solution

  • Place that code in viewDidAppear

Reason

  • viewDidLoad happens before autolayout is completed. So the position is not yet set by autolayout that was specified in xib
  • viewDidAppear happens after autolayout is completed.

Upvotes: 31

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