In my UIViewController class, I'm creating a UIView called safeAreaView and adding it as a subview to the UIViewControllers view property. I'm making it so safeAreaView takes up the entire safe area of the UIViewControllers view property:
- (void) viewDidLoad
{
[self setToolbarWithColor: self.mainToolbarColor animated:NO];
self.tapGestureRecognizer.delegate = self;
self.view.clipsToBounds = YES;
self.view.backgroundColor = [UIColor lightGrayColor];
self.safeAreaView = [[UIView alloc] initWithFrame: CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
self.safeAreaView.clipsToBounds = YES;
self.safeAreaView.delegate = self;
self.safeAreaView.translatesAutoresizingMaskIntoConstraints = NO;
[self.view addSubview: self.safeAreaView];
[self.safeAreaView.leadingAnchor constraintEqualToAnchor: self.view.safeAreaLayoutGuide.leadingAnchor].active = YES;
[self.safeAreaView.trailingAnchor constraintEqualToAnchor: self.view.safeAreaLayoutGuide.trailingAnchor].active = YES;
[self.safeAreaView.topAnchor constraintEqualToAnchor: self.view.safeAreaLayoutGuide.topAnchor].active = YES;
[self.safeAreaView.bottomAnchor constraintEqualToAnchor: self.view.safeAreaLayoutGuide.bottomAnchor].active = YES;
[self.safeAreaView loadSubviews];
}
This works fine, but my problem is, at some point after this during the UIViewControllers initialization cycle, safeAreaView updates to account for the statusbar (it's y position moves up 20 and it decreases in size by 20).
I need to layout some subviews on safeAreaView and I don't know the proper time? If I attach the subviews like above, they have the wrong height. And I can't use some auto layout features on the subviews because there are specific things that I need to do. I've also tried executing the above code in viewWillAppear with no luck.
Wondering if anyone had any suggestions?
You can override - (void)layoutSubviews on your safeAreaView class:
- (void)layoutSubviews {
[super layoutSubviews];
// Manual frame adjustment for non-autolayout participating subviews
// ...
}
Another option would be to override your safeAreaView's class frame setter, so each time the frame of your view changes, you'll get a chance to manually set any subview frames as needed.
I have used auto-layout and scrollview. I have created hierarchy in storyboard which looks as shown below :
Basically view has scrollview inside it and scrollview has another subview view1 inside it. Rest of the views are under view1.
While debugging one issue I am facing I show that self.scrollView.subviews prints 3 views. Out of them 2 are ImageViews. And those are not subview of scrollview as per the hierarchy in storyboard.
(lldb) po self.scrollView.subviews
<__NSArrayM 0xb66fe80>(
<UIView: 0xb74b110; frame = (0 0; 320 3240); autoresize = RM+BM; layer = <CALayer: 0xb74b170>>,
<UIImageView: 0xb7e61c0; frame = (313 476; 7 3); alpha = 0; opaque = NO; autoresize = TM; userInteractionEnabled = NO; layer = <CALayer: 0xb7e62a0>>,
<UIImageView: 0xb7e6350; frame = (314.5 3091.5; 3.5 36); alpha = 0; opaque = NO; autoresize = LM; userInteractionEnabled = NO; layer = <CALayer: 0xb7e6430>>
)
What can be wrong here? Ask for any detail you need.
The UIView on your console is this view
the 2 UIImageView's are the scroll indicators
And one cool thing to debug view hierarchy is recursiveDescription.
po [self.view recursiveDescription]
I'm having an issue with a view using autosizing resizing improperly in iOS7 (but fine in 6). The view initially renders as I'd expect, then I push another view onto the stack. Once I pop back to the original view, a subview that should be anchored on the right sizes itself too large and of the bounds of the superview.
It's a fairly simple view, created in a Storyboard, that includes the following hierarchy:
Scrollview -> View ->ImageView
It uses autosizing masks, which frankly was done because I had issues using autolayout inside the scrollview in this case (don't want to get into that here). The mask for the ImageView is pretty simple:
-
|
_
|-|<->|-|
-
|
-
On initial load, the X coord and width are as follows:
UIScrollView: frame = (0 64; 320 455); clipsToBounds = YES; autoresize
= W+H;
UIView: frame = (0 0; 320 568); autoresize = W+BM
UIImageView: frame = (20 110; 280 50); clipsToBounds = YES; opaque =
NO; autoresize = W;
On subsequent load, it appears as follows
UIScrollView: frame = (0 64; 320 455); clipsToBounds = YES; autoresize
= W+H
UIView: frame = (0 0; 320 568); autoresize = W+BM
UIImageView: frame = (20 160; 320 50); clipsToBounds = YES; opaque
= NO; autoresize = W
The notable difference being, as bolded, the width of the ImageView frame increases to 320, which is the size of it's bounds. Since it is still offset by 20, it ends up running off the screen. Obviously, I would expect it to stay at 280, as it does when this same thing is run in iOS6.
I don't manipulate the view in any way in code, so this should all be tied the autolayout masks. I cannot find anything about others having similar issues.
--
I have a reusable view I will be using in UITableViewCell's and UICollectionViewCell's, and need to get its dimensions for tableView:heightForRowAtIndexPath:. Some subviews have stuff going on inside layoutSubviews so I can't call systemLayoutForContentSize:, instead my plan is to:
Instantiate the metrics view.
Set the size to include the desired width.
Populate it with data.
Update constraints / Layout subviews.
Grab the height of the view or an internal "sizing" view.
The problem I'm running into is that I cannot force the view to layout without inserting it into the view and waiting for the runloop.
I've distilled a rather boring example. Here's View.xib. The subview is misaligned to highlight that the view is never getting laid out even to the baseline position:
On the main thread I call:
UIView *view = [[UINib nibWithNibName:#"View" bundle:nil] instantiateWithOwner:nil options:nil][0];
NSLog(#"Subviews: %#", view.subviews);
view.frame = CGRectMake(0, 0, 200, 200);
[view updateConstraints];
[view layoutSubviews];
NSLog(#"Subviews: %#", view.subviews);
[self.view addSubview:view];
[view updateConstraints];
[view layoutSubviews];
NSLog(#"Subviews: %#", view.subviews);
dispatch_async(dispatch_get_main_queue(), ^{
NSLog(#"Subviews: %#", view.subviews);
});
I get out the following view information:
1) "<UIView: 0x8bad9e0; frame = (50 50; 220 468); autoresize = W+H; layer = <CALayer: 0x8be0070>>"
2) "<UIView: 0x8bad9e0; frame = (50 50; 220 468); autoresize = W+H; layer = <CALayer: 0x8be0070>>"
3) "<UIView: 0x8bad9e0; frame = (50 50; 220 468); autoresize = W+H; layer = <CALayer: 0x8be0070>>"
4) "<UIView: 0x8bad9e0; frame = (0 100; 100 100); autoresize = W+H; layer = <CALayer: 0x8be0070>>"
1 indicates that the fresh-out-of-the-NIB view hasn't been laid out. 2 indicates that updateConstraints/layoutSubviews did nothing. 3 indicates that adding it to the view hierarchy did nothing. 4 finally indicates that adding to the view hierarchy and one pass through the main-loop laid out the view.
I would like to get to the point where I can get the view's dimensions without having to let the application handle it or perform manual calculations (string height + constraint1 + constraint2) on my own.
Update
I've observed that if I place view inside a UIWindow I get a slight improvement:
UIView *view = [[UINib nibWithNibName:#"View" bundle:nil] instantiateWithOwner:nil options:nil][0];
UIWindow *window = [[UIWindow alloc] initWithFrame:CGRectMake(0, 0, 200, 200)];
view.frame = CGRectMake(0, 0, 200, 200);
[window addSubview:view];
[view layoutSubviews];
If view.translatesAutoresizingMaskIntoConstraints == YES, the view's immediate subviews will be laid out, but none of their children.
The Autolayout Question
In the basic case you mentioned, you can get the correct size by calling setNeedsLayout and then layoutIfNeeded on the container view.
From the UIView class reference on layoutIfNeeded:
Use this method to force the layout of subviews before drawing. Starting with the receiver, this method traverses upward through the view hierarchy as long as superviews require layout. Then it lays out the entire tree beneath that ancestor. Therefore, calling this method can potentially force the layout of your entire view hierarchy. The UIView implementation of this calls the equivalent CALayer method and so has the same behavior as CALayer.
I don't think the "entire view hierarchy" applies to your use case since the metrics view presumably wouldn't have a superview.
Sample Code
In a sample empty project, with just this code, the correct frame is determined after layoutIfNeeded is called:
#import "ViewController.h"
#interface ViewController ()
#property (nonatomic, strong) UIView *redView;
#end
#implementation ViewController
#synthesize redView;
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
redView = [[UIView alloc] initWithFrame:CGRectMake(50, 50, 220, 468)];
redView.backgroundColor = [UIColor redColor];
redView.translatesAutoresizingMaskIntoConstraints = NO;
[self.view addSubview:redView];
NSLog(#"Red View frame: %#", NSStringFromCGRect(redView.frame));
// outputs "Red View frame: {{50, 50}, {220, 468}}"
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:#"H:|[redView(==100)]" options:0 metrics:Nil views:NSDictionaryOfVariableBindings(redView)]];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:#"V:|-100-[redView(==100)]" options:0 metrics:Nil views:NSDictionaryOfVariableBindings(redView)]];
NSLog(#"Red View frame: %#", NSStringFromCGRect(redView.frame));
// outputs "Red View frame: {{50, 50}, {220, 468}}"
[self.view setNeedsLayout];
NSLog(#"Red View frame: %#", NSStringFromCGRect(redView.frame));
// outputs "Red View frame: {{50, 50}, {220, 468}}"
[self.view layoutIfNeeded];
NSLog(#"Red View frame: %#", NSStringFromCGRect(redView.frame));
// outputs "Red View frame: {{0, 100}, {100, 100}}"
}
#end
Additional Considerations
Slightly outside the scope of your question, here are some other issues you may run into, since I've worked on this exact problem in a real app:
Calculating this in heightForRowAtIndexPath: might be expensive, so you may want to precalculate and cache the results
Precalculation should be done on a background thread, but UIView layout doesn't work well unless it's done on the main thread
You should definitely implement estimatedHeightForRowAtIndexPath: to reduce the impact of these performance issues
Using intrinsicContentSize
In response to:
Some subviews have stuff going on inside layoutSubviews so I can't call systemLayoutForContentSize:
You can use this method if you implement intrinsicContentSize, which lets a view suggest an optimal size for itself. One implementation for this might be:
- (CGSize) intrinsicContentSize {
[self layoutSubviews];
return CGSizeMake(CGRectGetMaxX(self.bottomRightSubview.frame), CGRectGetMaxY(self.bottomRightSubview.frame));
}
This simple approach will only work if your layoutSubviews method doesn't refer to an already-set size (like self.bounds or self.frame). If it does, you may need to do something like:
- (CGSize) intrinsicContentSize {
self.frame = CGRectMake(0, 0, 10000, 10000);
while ([self viewIsWayTooLarge] == YES) {
self.frame = CGRectInset(self.frame, 100, 100);
[self layoutSubviews];
}
return CGSizeMake(CGRectGetMaxX(self.bottomRightSubview.frame), CGRectGetMaxY(self.bottomRightSubview.frame));
}
Obviously, you'd need to adjust these values to match the particular layout of each view, and you may need to tune for performance.
Finally, I'll add that due in part to the exponentially increasing cost of using auto-layout, for all but the simplest table cells, I usually wind up using manual height calculation.
Presumably you're calling the demo code when the view controller first loads its view, like in viewDidLoad or another life cycle method. The nested subview's geometries won't reflect its constraints until viewDidLayoutSubviews is called. Nothing you do during the initial life cycle of a view controller will make that method arrive any faster.
Update 12/30/13: After testing Aaron Brager's sample code, I now realize that the previous paragraph is incorrect. Apparently, you can force layout in viewDidLoad by calling setNeedsLayout followed by layoutIfNeeded.
If you executed the demo code in response to a button click instead, I think you'll see the final geometries of your nested subview logged before the action method completes.
- (IBAction)buttonTapped:(id)sender
{
UIView *view = [[UINib nibWithNibName:#"View" bundle:nil] instantiateWithOwner:nil options:nil][0];
view.frame = CGRectMake(0, 0, 200, 200);
[self.view addSubview:view];
[self.view layoutIfNeeded];
NSLog(#"Subviews: %#", view.subviews);
}
In the latter case, you can request layout on-demand because the view controller has completed its initial setup.
But during a view controller's initial setup, how are you going to get the final geometries of your re-usable subview?
After you set the content for the re-usable subview, have your view controller ask the subview for its size. In other words, implement a method on your custom view that calculates the size based on the content.
For example, if the subview's content is an attributed string, you could use a method like boundingRectWithSize:options:context: to help determine the size of your subview.
CGRect rect = [attributedString boundingRectWithSize:CGSizeMake(width, CGFLOAT_MAX) options:NSStringDrawingUsersLineFragmentOrigin context:nil];
I have one UIViewController container with contains multiple UIViewController boxes. I'd like to apply physics behaviour to the boxes using UIKit Dynamics. The container defines the outer border.
The UIDynamicAnimator is an object in the container and all Dynamics behaviours are part of the boxes.
Problem: I run into error messages when I reference the animator from the boxes (childviewcontrollers) for adding the box behaviours.
Here's the error message
> Terminating app due to uncaught exception
> 'NSInvalidArgumentException', reason: 'View item (<UIView: 0x9972720;
> frame = (0 568; 120 40); clipsToBounds = YES; autoresize = W+H;
> gestureRecognizers = <NSArray: 0x9976f80>; layer = <CALayer:
> 0x9972780>>) should be a descendant of reference view in
> <UIDynamicAnimator: 0x9906d40> Stopped (0.000000s) in <UIView:
> 0x9916bf0> {{0, 0}, {320, 568}}'
UIViewController Container
- (void)viewDidLoad
{
[super viewDidLoad];
UIDynamicAnimator* animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.view];
_animator = animator;
...
}
Adding Boxes as Subviews and ChildViewControllers
- (void)tapOnContainer:(UITapGestureRecognizer*)touch {
...
BoxViewController *note = [[BoxViewController alloc]init];
[box setContainerObject:self];
[self addChildViewController:box];
[self.view addSubview:box.view];
}
UIViewController Box
- (void)viewDidLoad
{
_containerViewController = (ViewController*) self.parentViewController;
_gravityBehaviour = [[UIGravityBehavior alloc]initWithItems:#[self.view]];
[_containerViewController.animator addBehavior:_gravityBehaviour];
...
}
Any idea how to get this working? Is it okay to split the UIDynamicAnimator and the UIDynamicBehavior objects like this?
In this line:
_gravityBehaviour = [[UIGravityBehavior alloc]initWithItems:#[self.view]];
Add your small view instead of self.view.