UIView Animation 完成后移除 layer.cornerRadius

Question

I have a UILabel that I am animating the constraints for so that it drop down into view. I am using layer.cornerRadius to give the view rounded corners, but for whatever reason after the animation completes the corner radius is removed.

[UIView animateWithDuration:0.3 delay:0 usingSpringWithDamping:0.7 initialSpringVelocity:0.4 options:UIViewAnimationOptionCurveEaseInOut animations:^{
        
        if (shouldShow) {
            
            self.labelOverMapTopConstraint.constant = 16;
            
        } else {
            
            self.labelOverMapTopConstraint.constant = -40;
            
        }
        
        [self.view layoutIfNeeded];
        
} completion:nil];

cornerRadius is set in viewDidLoad .

Is there a way to prevent this from happening?

Answer 1

I suspect you're subclassing UILabel here since it looks like you have padding in there, is that correct?

There could be something going awry with any custom drawing/calculations you're doing in there, so it would probably be helpful to post that code for inspection as well.

A few questions:

• Do you have masksToBounds set to YES?
• If you're not using a custom UILabel subclass, are you wrapping the label in a view?
• How is the animation being triggered? Is it by a button? A callback from a NSURLRequest? If it's triggered by an async callback are you jumping back on the main queue to perform the animation?
• If the animation is triggered automatically within the lifecycle, which lifecycle method is it triggered in?

I wasn't able to reproduce the issue in a test project with a vanilla UILabel. I then tried it with a UILabel subclass which includes additional padding and still wasn't able to reproduce it there.

I've included example code snippets below:

#import "ViewController.h"
#import "R4NInsetLabel.h"

@interface ViewController ()
@property BOOL showingToast;
@property (strong, nullable) IBOutlet R4NInsetLabel *toastLabel;
@property (strong, nullable) IBOutlet NSLayoutConstraint *toastLabelTopConstraint;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.navigationController.navigationBar.titleTextAttributes = @{NSForegroundColorAttributeName : [UIColor whiteColor]};
    self.showingToast = NO;
    // start with the label pushed off the top of the screen
    self.toastLabelTopConstraint.constant = -40.0f;
    self.toastLabel.layer.cornerRadius = 6.0f;
    self.toastLabel.layer.masksToBounds = YES;
}

- (IBAction)toggleToast:(id)sender {
    [UIView animateWithDuration:0.3 delay:0 usingSpringWithDamping:0.7 initialSpringVelocity:0.4 options:UIViewAnimationOptionCurveEaseInOut animations:^{
            if (self.showingToast == NO) {
                self.toastLabelTopConstraint.constant = 16;
                self.showingToast = YES;
            } else {
                self.toastLabelTopConstraint.constant = -40;
                self.showingToast = NO;
            }
            [self.view layoutIfNeeded];
    } completion:nil];
}

@end

#import "R4NInsetLabel.h"

IB_DESIGNABLE
@interface R4NInsetLabel()
@property IBInspectable CGFloat contentPadding;
@property (nonatomic) UIEdgeInsets contentInsets;
- (CGSize)_addInsetsToSize:(CGSize)size;
@end

@implementation R4NInsetLabel

- (UIEdgeInsets)contentInsets {
    return UIEdgeInsetsMake(self.contentPadding, self.contentPadding, self.contentPadding, self.contentPadding);
}

- (CGSize)_addInsetsToSize:(CGSize)size {
    CGFloat width = size.width + self.contentInsets.left + self.contentInsets.right;
    CGFloat height = size.height + self.contentInsets.top + self.contentInsets.bottom;
    return CGSizeMake(width, height);
}

- (void)drawTextInRect:(CGRect)rect {
    CGRect insetRect = UIEdgeInsetsInsetRect(rect, self.contentInsets);
    [super drawTextInRect:insetRect];
}

- (CGSize)intrinsicContentSize {
    CGSize baseSize = [super intrinsicContentSize];
    return [self _addInsetsToSize:baseSize];
}

- (CGSize)sizeThatFits:(CGSize)size {
    CGSize baseSize = [super sizeThatFits:size];
    return [self _addInsetsToSize:baseSize];
}

@end

And here's what it looks like:

Answer 2

You also need to set the corner radius on viewDidLayoutSubviews

override func viewDidLayoutSubviews() {

    super.viewDidLayoutSubviews()
    label.layer.cornerRadius = yourValue
}