How to fade in and fade out a label. continuously - objective-c

Question

In my Xcode project I have put a label on an xib.
I want to fade the label in and out continuously until the user taps the screen. When this happens I want a new view to appear.
Can anyone suggest how to do the fade-in/out?

Answer 1

Instead of nesting blocks and manually restarting your animations, you can use the option pair UIViewAnimationOptionAutoreverse | UIViewAnimationOptionRepeat to tell Core Animation you want the label to fade in and out continuously.
- (void)startAnimatingLabel
{
self.label.alpha = 0;
[UIView animateWithDuration:1
delay:0
options: UIViewAnimationOptionAutoreverse | UIViewAnimationOptionRepeat
animations:^{
self.label.alpha = 1;
} completion:nil];
}
To stop the animations from running, just remove them from the label's layer.
- (IBAction)tap:(UITapGestureRecognizer *)sender
{
[self.label.layer removeAllAnimations];
self.label.alpha = 0;
[self presentNewView];
}
EDIT: A less abrupt way to finish would be to animate from the current view state to the final one (this will interrupt the current, repeating animation).
- (IBAction)tap:(UITapGestureRecognizer *)sender
{
[UIView animateWithDuration:1
delay:0
options:UIViewAnimationOptionBeginFromCurrentState
animations:^{
self.label.alpha = 0;
} completion:^(BOOL finished){
[self presentNewView];
}];
}

Answer 2

You could put a pair of chained animation in a loop or call a function that holds the chained animation everytime until you encounter a user tap.
By Chained animation, I mean something like this (You can set the animation duration to suit your needs):
myLabel.alpha = 0.0;
[UIView animateWithDuration:1.0
delay:0.0
options: UIViewAnimationCurveEaseOut
animations:^{
myLabel.alpha = 1.0;
}
completion:^(BOOL finished){
[UIView animateWithDuration:1.0
delay:1.0
options: UIViewAnimationCurveEaseOut
animations:^{
myLabel.alpha = 0.0;
}
completion:^(BOOL finished){
NSLog(#"Done!");
}];
}];
The above code will first fade in your label and then fade it out. You can put that in a function and call it until you encounter user tap.

Answer 3

Create a CABasicAnimation and add it to your label:
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:#"opacity"];
animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
animation.fromValue = #(1.0f);
animation.toValue = #(0.1f);
animation.repeatCount = INFINITY;
animation.duration = 0.75;
animation.autoreverses = YES;
[label.layer addAnimation:animation];
When you click on your button, just get a pointer to that label and remove all the animations:
[label.layer removeAllAnimations];

Answer 4

Try this it give you the ability to manage the animation repeat count if you replaced INFINITY with your repeat count
fadingLabel.alpha = 1.0;
[UIView beginAnimations:#"fadingLabel" context:nil];
[UIView setAnimationDuration:4.0];
[UIView setAnimationRepeatCount:INFINITY];
fadingLabel.alpha = 0.0;
[UIView setAnimationBeginsFromCurrentState:YES];
[UIView commitAnimations];

Answer 5

Wayne Hartman's Answer in Swift 4
let animation = CABasicAnimation(keyPath: "opacity")
animation.fromValue = 1
animation.toValue = 0.1
animation.duration = 0.75
animation.repeatCount = .infinity
animation.autoreverses = true
label.layer.add(animation, forKey: nil)
and
label.layer.removeAllAnimations()