iOS continuous fade-out and fade-in animation - ios

Question

In objective-c, I want to add fade in and fade out animation to a UIView. I want to do the fade-out and fade-in animation continuously. To illustrate it, what effect I want to have is as following:
fade out - fade in - fade out - fade in - ...
What I'm trying is as following:
-(void)fadeOutIn:(UIView *)view duration:(NSTimeInterval)duration
{
static CGFloat alpha = 1.0;
[UIView animateWithDuration:duration
delay:0.0
options: UIViewAnimationOptionRepeat| UIViewAnimationOptionCurveEaseInOut
animations:^{
alpha = abs((int)(alpha - 1.0));
view.alpha = alpha;
}
completion:^(BOOL finished){
}];
}
I also tried following:
-(void)fadeOutIn:(UIView *)view duration:(NSTimeInterval)duration
{
[UIView animateWithDuration:duration
delay:0.0
options: UIViewAnimationOptionRepeat| UIViewAnimationOptionCurveEaseInOut
animations:^{
view.alpha = 0.0;
}
completion:^(BOOL finished){
[UIView animateWithDuration:duration
delay:0.0
options: UIViewAnimationOptionRepeat|UIViewAnimationOptionCurveEaseInOut
animations:^{
view.alpha = 1.0;
}
completion:^(BOOL finished){
}];
}];
}
But the issue is they worked all the same, i.e., the UIView will fade out properly and SUDDENLY show up(not fade in), then fade out again...
Seems the fade in animation not work at all. Does anybody know what's wrong of my code please? Any suggestion will be highly appreciated.

Answer 1

Try this
[UIView animateKeyframesWithDuration:1 delay:0 options:UIViewAnimationOptionRepeat|UIViewAnimationOptionAutoreverse|UIViewAnimationCurveEaseInOut animations:^{
self.customIV.alpha = 0;
} completion:^(BOOL finished) {
}];

Answer 2

Here's this, Vigor, this does work, but I had to modify the code, this is somewhat dangerous code, due to it's constant recursiion, but you'll get the point:
-(void)fadeOutIn
{
[UIView animateWithDuration:1
delay:0.0
options: UIViewAnimationOptionCurveEaseInOut
animations:^{
[[self contentView] emailField].alpha = 0.0;
}
completion:^(BOOL finished){
[UIView animateWithDuration:1
delay:0.0
options: UIViewAnimationOptionCurveEaseInOut
animations:^{
[[self contentView] emailField].alpha = 1.0;
}
completion:^(BOOL finished){
[self fadeOutIn];
}];
}];
}
I would really rethink how this works, I used it on a button in my view and it will recurse constanly, until the view is removed from the superview. I had to hardcode the button in the code.

Answer 3

[UIView animateWithDuration:duration
delay:0.0
options: UIViewAnimationOptionRepeat| UIViewAnimationOptionAutoreverse|UIViewAnimationOptionCurveEaseInOut
animations:^{
view.alpha = 0.0;
}
completion:nil];
Just call this once

Answer 4

Try this....
YourView.alpha = 1;// set the initial value of alpha
[UIView animateWithDuration:1 delay:0
options: UIViewAnimationOptionAutoreverse | UIViewAnimationOptionRepeat
animations:^{
YourView.alpha = 0; // set the max value of alpha
} completion:nil];

Answer 5

This solution is for Swift 3,4 and 5
UIView.animateKeyframes(withDuration: 1, delay: 0, options: [UIView.KeyframeAnimationOptions(rawValue: UIView.AnimationOptions.repeat.rawValue), UIView.KeyframeAnimationOptions(rawValue: UIView.KeyframeAnimationOptions.RawValue(UIView.AnimationCurve.easeInOut.rawValue)), UIView.KeyframeAnimationOptions(rawValue: UIView.AnimationOptions.autoreverse.rawValue)] , animations: {
self.logoCenterImageView.alpha = 0
}) { finished in
}