UIViewController returns invalid frame?

Question

When I start my ViewController in landscape mode (After viewDidLoad is called), I print the frame it's giving me the frame size for portrait mode instead.

Is this a bug any suggestions?

- (void)viewDidLoad
{
   [super viewDidLoad];

   NSLog(@"%@", NSStringFromCGRect(self.view.frame));
   // Result is (0, 0 , 768, 1024)
}

Innards

And what about viewDidAppear? – Allay

Answer 1

There are a couple of things that you don't understand.

First, the system sends you viewDidLoad immediately after loading your nib. It hasn't even added the view to the view hierarchy yet. So it hasn't resized your view based on the device's rotation either.

Second, a view's frame is in its superview's coordinate space. If this is your root view, its superview will be the UIWindow (once the system actually adds your view to the view hierarchy). The UIWindow handles rotation by setting the transform of its subview. This mean that the view's frame will not necessarily be what you expect.

Here's the view hierarchy in portrait orientation:

(lldb) po [[UIApp keyWindow] recursiveDescription]
(id) $1 = 0x09532dc0 <UIWindow: 0x9632900; frame = (0 0; 768 1024); layer = <UIWindowLayer: 0x96329f0>>
   | <UIView: 0x9634ee0; frame = (0 20; 768 1004); autoresize = W+H; layer = <CALayer: 0x9633b50>>

and here's the view hierarchy in landscape-left orientation:

(lldb) po [[UIApp keyWindow] recursiveDescription]
(id) $2 = 0x09635e70 <UIWindow: 0x9632900; frame = (0 0; 768 1024); layer = <UIWindowLayer: 0x96329f0>>
   | <UIView: 0x9634ee0; frame = (20 0; 748 1024); transform = [0, -1, 1, 0, 0, 0]; autoresize = W+H; layer = <CALayer: 0x9633b50>>

Notice that in landscape orientation, the frame size is 748 x 1024, not 1024 x 748.

What you probably want to look at, if this is your root view, is the view's bounds:

(lldb) p (CGRect)[0x9634ee0 bounds]
(CGRect) $3 = {
  (CGPoint) origin = {
    (CGFloat) x = 0
    (CGFloat) y = 0
  }
  (CGSize) size = {
    (CGFloat) width = 1024
    (CGFloat) height = 748
  }
}

Presumably you want to know when the view's transform, frame, and bounds get updated. If the interface is in a landscape orientation when your view controller loads its view, you will receive messages in this order:

{{0, 0}, {768, 1004}} viewDidLoad
{{0, 0}, {768, 1004}} shouldAutorotateToInterfaceOrientation:
{{0, 0}, {768, 1004}} shouldAutorotateToInterfaceOrientation:
{{0, 0}, {768, 1004}} viewWillAppear:
{{0, 0}, {768, 1004}} shouldAutorotateToInterfaceOrientation:
{{0, 0}, {768, 1004}} shouldAutorotateToInterfaceOrientation:
{{0, 0}, {768, 1004}} willRotateToInterfaceOrientation:duration:
{{0, 0}, {1024, 748}} viewWillLayoutSubviews
{{0, 0}, {1024, 748}} layoutSubviews
{{0, 0}, {1024, 748}} viewDidLayoutSubviews
{{0, 0}, {1024, 748}} willAnimateRotationToInterfaceOrientation:duration:
{{0, 0}, {1024, 748}} shouldAutorotateToInterfaceOrientation:
{{0, 0}, {1024, 748}} viewDidAppear:

You can see that your view's bounds change after you receive willRotateToInterfaceOrientation:duration: and before you receive viewWillLayoutSubviews.

The viewWillLayoutSubviews and viewDidLayoutSubviews methods are new to iOS 5.0.

The layoutSubviews message is sent to the view, not the view controller, so you will need to create a custom UIView subclass if you want to use it.

Piscary

the key thing for me was using bounds instead of frame. Thanks! – Alburga

Hey Rob, hopefully you see this -- how did you get that dump of the order of the methods invoked when the controller loads its view? – Almost

I put an NSLog in each method. – Piscary

Thanks so much for this. The simple chronological list of methods is amazingly useful, and something that should be prominent in Apple's documentation. Even better would be a state diagram for the various transitions that can then occur, with the method call ordering on the edges. – Kolomna

Answer 2

Here's a clean solution.

I was experiencing the same issue and I insist on using frame throughout my app. I do not want to make an exception for the root view controller. I noticed that the root view controller's frame was displaying portrait dimensions, but all subviews had correct landscape dimensions.

Since it is only the root view controller that behaves differently, we can set a standard, blank view controller as the root view controller and add our custom view controller to that. (Code below.)

You can then use frame as you intend to, in your custom view controller.

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    // Override point for customization after application launch.

    self.window.rootViewController = [[UIViewController alloc] init];

    [self.window makeKeyAndVisible];

    self.viewController = [[ViewController alloc] initWithNibName:nil bundle:nil];
    [self.window.rootViewController addChildViewController:self.viewController];
    [self.window.rootViewController.view addSubview:self.viewController.view];

    return YES;
}

Shy

Answer 3

Here is an alternate solution (Swift 4):

override func viewDidLoad() {
    super.viewDidLoad()
    self.view.setNeedsLayout()
    self.view.layoutIfNeeded()
}

Basically this forces the view controller to correctly layout it's view and from there you can get the correct frames for all your subviews. This particularly helps when doing transition animations and your view controllers are using autolayout and interface builder.

From what I've noticed it looks like the initial frames are set to whatever your interface builder's default size class is set to. I normally edit using the iPhone XS size class so in viewDidLoad it seems that the view's width is always 375 regardless whether you are using an iPhone XR or not. This corrects itself before viewWillAppear though.

The above code will correct this issue and allow you to get the correct frames for your view / subviews before the view controller is rendered to the screen.

Hydroxy