UIImageView alpha fade animation issue

[nicksayes]

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

[unvjarhead]

This is terribly inefficient, but it might help.

If you are having problems with number type compatibility, package both into the NSNumber class and use it's compare methods.

something like

if ( NSOrderedAscending == [[NSNumber numberWithDouble:fadeImageView.alpha] compare:[NSNumber numberWithDouble:1.0]){

I don't know why your code isn't working, but this might make the compiler word the error differently if it's a problem somewhere else.