Why doesn't my animation loop? - objective-c

Question

I need to perform a blinking effect on a image once the user click on a particular button. But my code doesn't work:
- (void)next
{
[UIView animateWithDuration:2.0f delay:0 options:UIViewAnimationOptionAutoreverse | UIViewAnimationOptionRepeat animations:^{
NSLog(#"Done"); // <- USED AS COUNTER
[image setAlpha:0];
[image setAlpha:0.5];
} completion:nil];
}
What happens is my image changing its alpha to 0.5 and stops. Furthermore my console shows DONE just one time. What did I wrong?

Answer 1

I just created a test project and this blinked just fine...
#import "ViewController.h"
#interface ViewController ()
#property (nonatomic, strong)UIView *blinker;
#end
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.blinker = [[UIView alloc]initWithFrame:CGRectMake(0, 0, 100, 100)];
self.blinker.backgroundColor = [UIColor greenColor];
[self.view addSubview:self.blinker];
[self next];
}
- (void)next
{
[UIView animateWithDuration:2.0f delay:0 options:UIViewAnimationOptionAutoreverse | UIViewAnimationOptionRepeat animations:^{
NSLog(#"Done"); // <- USED AS COUNTER
[self.blinker setAlpha:0];
[self.blinker setAlpha:0.5];
} completion:nil];
}
With the exception that you expect the log to continue to print out in the console. So I suspect you are doing something to your image. You aren't calling self. so I am guessing it is an instance variable (ivar) and you are changing what it points to somewhere else in the code.
If you need a counter to go off every blink you may want to consider something like this...
#import "ViewController.h"
#interface ViewController ()
#property (nonatomic, strong)UIView *blinker;
#property (nonatomic,)NSInteger counter;
#end
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.blinker = [[UIView alloc]initWithFrame:CGRectMake(0, 0, 100, 100)];
self.blinker.backgroundColor = [UIColor greenColor];
[self.view addSubview:self.blinker];
[self next];
}
- (void)next
{
[UIView animateWithDuration:1.0 animations:^{
self.counter++;
NSLog(#"Counter: %#", #(self.counter));
self.blinker.alpha = 0.0;
} completion:^(BOOL finished) {
[UIView animateWithDuration:1.0 animations:^{
self.blinker.alpha = 1.0;
} completion:^(BOOL finished) {
//check to see if you want to continue blinking if so call next again
[self next];
}];
}];
}
I don't have any context as to why you want to count, but hopefully that helps.