Question

I’ve adopted a fairly well used method of flipping between two images. However on this occasion, for reasons currently beyond me – the animation is currently only flipping from “newView” to “newView.”

Any help pointing towards the error of my ways would be greatly appreciated. Code as follows:

UIImageView *oldView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"dark_wood.png"]];
UIImageView *newView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"light_wood.png"]];
[container addSubview:oldView];

and:

[UIView transitionWithView:container
                  duration:2
                   options:UIViewAnimationOptionTransitionFlipFromLeft
                animations:^{ [oldView removeFromSuperview]; [container addSubview:newView]; }
                completion:nil];

(It’s probably something v.simple beyond this code..)

Answer 1

The solution:

The method I was using to initiate the flip was at fault. I had a UISlider call for the flip – but without a system in place to stop it from doing so, it was continuously calling the flip animation – with the consequences as described!

Solution in code as follows:

Create a BOOL to stop the UISlider repeatedly calling the animation:

BOOL playing;

IBAction for the UISlider:

- (IBAction)slider:(id)sender {
    if (!playing) {
        [UIView transitionWithView:self.view
                      duration:3
                       options:UIViewAnimationOptionTransitionFlipFromLeft
                    animations:^{ [view1 removeFromSuperview]; [self.view addSubview:view2]; }
                    completion:nil];
        playing = YES;
    }
}

Thanks to Tony for helping with this. A lesson if ever there was one to keep the script clean!