btn变大变小的效果

//btn变大变小的效果- (void)imgAnimate:(UIButton*)btn{    UIView *view=btn.subviews[0];    [UIView animateWithDuration:0.1 animations:     ^(void){          view.transform = CGAffineTransformScale(CGAffineTransformIdentity,0.8, 0.8);     } completion:^(BOOL finished){//do other thing         [UIView animateWithDuration:0.2 animations:          ^(void){              view.transform = CGAffineTransformScale(CGAffineTransformIdentity,1.2, 1.2);          } completion:^(BOOL finished){//do other thing              [UIView animateWithDuration:0.1 animations:               ^(void){                   view.transform = CGAffineTransformScale(CGAffineTransformIdentity,1,1);               } completion:^(BOOL finished){//do other thing               }];          }];     }];   }