Recursive animateWithDuration: animations: completion: method iOS - ios

Question

I am attempting to make my item "glow" every 3 seconds changing its alpha from a high to low value and back. It however "flickers" and basically changes every 0.2 seconds from color to color randomly. I have pasted the method below. Its probably something to do with when completion is called but not sure?
-(void)showLoading{
[self.postTableView setHidden:YES];
self.isLoading = true;
//Disappear
[UIView animateWithDuration:1.5 animations:^(void) {
self.loadingLabel.alpha = 0.8;
self.loadingLabel.alpha = 0.3;
}
completion:^(BOOL finished){
//Appear
[UIView animateWithDuration:1.5 animations:^(void) {
self.loadingLabel.alpha = 0.3;
self.loadingLabel.alpha = 0.8;
}completion:^(BOOL finished2){
if(true){
[self showLoading];
}
}];
}]; }

Answer 1

self.loadingLabel.alpha = .8;
[UIView animateWithDuration:1.5 delay:0 options:UIViewAnimationOptionAutoreverse | UIViewAnimationOptionRepeat animations:^{
self.loadingLabel.alpha = .3;
} completion:nil];
UIViewAnimationOptionAutoreverse & UIViewAnimationOptionRepeat can help you.
you can stop it by
self.loadingLabel.alpha = .8;
or the other animation.
[UIView animateWithDuration:1.5 delay:0 options:UIViewAnimationOptionBeginFromCurrentState animations:^{
self.loadingLabel.alpha = .8;
} completion:nil];
UIViewAnimationOptionBeginFromCurrentState is a useful option for you to stop your animation by the other animation.

Answer 2

-(void)viewDidLoad{
//use schedule timer to call repeatedly showLoading method until loading done
}
-(void)showLoading{
[self.postTableView setHidden:YES];
self.isLoading = true;
[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:1.5];
[UIView setAnimationCurve:UIViewAnimationCurveEaseIn];
self.loadingLabel.alpha = 0.3;
[UIView commitAnimations];
[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:1.5];
[UIView setAnimationCurve:UIViewAnimationCurveEaseIn];
self.loadingLabel.alpha = 0.8;
[UIView commitAnimations];
}