Open Radar

 
Area:
UIKit

Summary:
When animating the multiple values of a frame of some view with a very small duration (for example 0.00001) - the animation does not take place and all subsequent animations to that view complete instantly.

Steps to Reproduce:
- (void)reproduceBug
{
    CGRect initialFrame = CGRectMake(0, 0, 0, 0);
    CGRect frame2 = CGRectMake(100, 100, 100, 100);
    CGRect finalFrame = CGRectMake(200, 200, 200, 200);
    
    
    __block UIView *view = [[UIView alloc] initWithFrame:initialFrame];
    view.backgroundColor = [UIColor greenColor];
    [self.view addSubview:view];
    
    NSLog(@"Initial frame is: %@", NSStringFromCGRect(view.frame));
    NSLog(@"Final frame should be: %@", NSStringFromCGRect(finalFrame));

    [UIView animateWithDuration:0.00000001 delay:0.0
                        options:UIViewAnimationOptionBeginFromCurrentState
                     animations:^{
                         view.frame = frame2;
                     } completion:^(BOOL finished) {
                             NSLog(@"After first animation frame is: %@", NSStringFromCGRect(view.frame));

                             [UIView animateWithDuration:.1 delay:0.0 options:UIViewAnimationOptionBeginFromCurrentState animations:^{
                                 view.frame = finalFrame;
                             }completion:^(BOOL finished) {
                                 NSLog(@"After second animation frame is: %@", NSStringFromCGRect(view.frame));
                                 [self doFurtherAnimationOnView:view];
                             }];
                     }];
    
}

Expected Results:
Initial frame is: {{0, 0}, {0, 0}}
Final frame should be: {{200, 200}, {200, 200}}
After first animation frame is: {{150, 150}, {0, 0}}
After second animation frame is: {{300, 300}, {0, 0}}


Actual Results:
A green square view appears on screen with no animation.

Version:
iOS 9.3

Notes:
A tiny project that reproduces the bug:
https://github.com/alexgo84/UIViewAnimationBug

Configuration:
iPhone simulator 6s Plus



Reproduces on iOS 8.4 and iOS 9.3.