Question

In my app, I run numerous animations, moving objects and shapes etc.
Many of the animations lead on to the animation of other objects.
A problem with the application is that if an animation is running and you start another that involves one of the objects currently being animated, the screen goes white/we get unexpected results.

I worked up some sample code to show what we are trying to do:

UIButton *button;
BOOL currentlyShowingQuestion;
- (void)viewDidLoad
{
    [self moveButton:button];
    currentlyShowingQuestion = NO;
    [NSTimer scheduledTimerWithTimeInterval:.1 target:self selector:@selector(hasBoolChanged) userInfo:nil repeats:YES];
}
- (void)moveButton:(UIButton *)buttonToUse {
    currentlyShowingQuestion = YES;
    NSLog(@"moveButton Called!  Yippee!!!!!!!");
    [UIView animateWithDuration:0.5 delay:0.5 options:nil animations:^{
        buttonToUse.frame = CGRectMake(10, 10, 300, 440);
    } completion:^(BOOL finished){
        currentlyShowingQuestion = NO;
    }];
}

-(void)hasBoolChanged {
    if (currentlyShowingQuestion == YES) {
        NSLog(@"Yes");
    }
    else if (currentlyShowingQuestion == NO) {
        NSLog(@"No");
    }
}

What I end up actually seeing is like the currentlyShowingQuestion BOOL both get changed instantly when the method is run, so it changes to YES and instantly back to NO. Then the animation runs. Why is this? What’s wrong with the order?

Any help appreciated.
Sorry about the code formatting – I couldn’t figure out the syntax here.

Thanks in advance,

Sam

Answer 1

I don’t really understand what you try to achieve. At the beginning you start a timer that checks whether the value of the boolean has changed. I think it is kind of an overkill for this task but thats ok.
Your animation is delayed 0.5s for some reason and then you have a 0.5s duration for an animation and that is really fast so it could seem that you instantly change the value.