View shake

shake.m

CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"position"];
[animation setDuration:0.08];
[animation setRepeatCount:3];
[animation setAutoreverses:YES];
[animation setFromValue:[NSValue valueWithCGPoint:
                         CGPointMake([formContainer center].x - 20.0f, [formContainer center].y)]];
animation setToValue:[NSValue valueWithCGPoint:
                       CGPointMake([formContainer center].x + 20.0f, [formContainer center].y)]];
[[formContainer layer] addAnimation:animation forKey:@"position"];