UIImageView alpha fade animation issues

Question

I'm a newbie iPhone developer going very well, almost finished my first app minus this one issue which I am a little embarrassed to be asking but...
I have a UIImageView that I have animated to fade (alpha value) over the period of 60s. After the animation a UIButton displays. In addition by tapping you can force the alpha value of the UIImageView down as to make the animation appear faster. But I am having trouble determining when the alpha value of my UIImageView is below zero - so that I can display the button - even though the animation is still running. Here is my code:
- (void)fadeTheImageView
[fadeImageView setAlpha:1.0];
[UIView beginAnimations:@"theAnimation" context:NULL];
[UIView setAnimationDelegate:self];
[UIView setAnimationDidStopSelector:@selector(yourAnimationHasFinished:finished:context :)];
[UIView setAnimationDuration:10];
[fadeImageView setAlpha:0.0];
[UIView commitAnimations];
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
if ( fadeImageView.alpha <= 0.0 ) {
[saveButton setHidden:NO];
[fadeImageView setAlpha:(fadeImageView.alpha - 0.1)];
- (void)yourAnimationHasFinished:(NSString *)animationID finished:(BOOL)finished context:(void *)context;
[saveButton setHidden:NO];
The error is with the if ( fadeImageView.alpha <= 0.0 ) {
incompatible variable types.
I've tried everything.
Any help would be appreciated

Answer 1

I've worked around the problem.
What I have done is to animate the alpha of the button along side the UIImageView.
So no need to rely on that conditional.
- (void)fadeTheImageView
UIImage *fadeImage = [UIImage imageNamed:@"Base.png"];
fadeImageView.image = fadeImage;
[fadeImageView setAlpha:1.0];
[saveButton setHidden:NO];
[saveButton setAlpha:-10.0];
[UIButton beginAnimations:@"saveButton" context:NULL];
[UIButton setAnimationDuration:30];
[saveButton setAlpha:1.0];
[UIButton commitAnimations];
[UIView beginAnimations:@"theAnimation" context:NULL];
[UIView setAnimationDelegate:self];
[UIView setAnimationDidStopSelector:@selector(yourAnimationHasFinished:finished:context:)];
[UIView setAnimationDuration:30];
[fadeImageView setAlpha:0.0];
[UIView commitAnimations];
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
[saveButton setAlpha:(saveButton.alpha + 1.0)];
[fadeImageView setAlpha:(fadeImageView.alpha - 0.1)];
- (void)yourAnimationHasFinished:(NSString *)animationID finished:(BOOL)finished context:(void *)context;
[saveButton setAlpha:1.0];