I can't figure this out, and I don't think this really explains it either.
I have a UILabel that can be tapped by the user to hide or show it, set up like this:
self.numberLabel.userInteractionEnabled = YES;
UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc]
initWithTarget:self action:@selector(hideOrShowNumber)];
[self.numberLabel addGestureRecognizer:tapGesture];
I would like to animate the hiding and showing of the label by setting the alpha value on the UILabel. However, if I set the alpha value to 0.0f, the label no longer accepts taps, so even if the user can hide the label, she can't show it anymore!
My workaround goes like this:
When hiding the label: - Animate the alpha value to 0.0f. - Set the text color of the label to black (which makes it invisible because the background is black) - Reset the alpha to 1.0f.
When showing the label: - Set the alpha to 0.0f (because it was left at 1.0f when the label was hidden). - Set the text color to another color than black (depending on game state). - Animate the alpha value to 1.0f.
The code looks like this (there are some state variables included, but self.numberLabel is the reference to the UILabel):
NSTimeInterval duration = 0.6f;
if (self.numberIsVisible) {
[UIView animateWithDuration:duration
animations:^{
self.numberLabel.alpha = 0.0f;
}
completion:^(BOOL done) {
self.numberLabel.textColor = [UIColor blackColor];
self.numberLabel.alpha = 1.0f;
}
];
self.numberIsVisible = NO;
}
else {
UIColor *rightColor = [UIColor whiteColor];
if ([GameState sharedGameState].haveMatch) {
rightColor = [UIColor colorWithRed:0.0/255.0 green:127.0/255.0 blue:255.0/255.0 alpha:1.0];
}
self.numberLabel.alpha = 0.0f;
self.numberLabel.textColor = rightColor;
[UIView animateWithDuration:duration
animations:^{
self.numberLabel.alpha = 1.0f;
}
];
self.numberIsVisible = YES;
}
It works, but it is a little clunky.
So the question is, why does setting the transparency of the UILabel make it lose user interaction? Is this by design, and is it documented somewhere? I can't find anything about this in the UIGestureRecognizer docs.
