Indefinite Animation

-(void)animateButton{
    [UIView animateWithDuration:1.0 animations:
     ^(void)
     {
         [_animationBGView setAlpha:0];
     }
                     completion:
     ^(BOOL finished)
     {
         [UIView animateWithDuration:1.0 animations:
          ^(void)
          {
              [_animationBGView setAlpha:1];
          }
                          completion:
          ^(BOOL finished)
          {
              [self animateButton];
          }];
     }];
}