textField输入错误时抖动提示的动画

其实就是一个简单的关键帧动画

+ (void)controlsShakeForView:(UIView *)view {
    CAKeyframeAnimation *keyAn = [CAKeyframeAnimation animationWithKeyPath:@"position"];
    [keyAn setDuration:0.5f];
    NSArray *array = [[NSArray alloc] initWithObjects:
                      [NSValue valueWithCGPoint:CGPointMake(view.center.x, view.center.y)],
                      [NSValue valueWithCGPoint:CGPointMake(view.center.x-5, view.center.y)],
                      [NSValue valueWithCGPoint:CGPointMake(view.center.x+5, view.center.y)],
                      [NSValue valueWithCGPoint:CGPointMake(view.center.x, view.center.y)],
                      [NSValue valueWithCGPoint:CGPointMake(view.center.x-5, view.center.y)],
                      [NSValue valueWithCGPoint:CGPointMake(view.center.x+5, view.center.y)],
                      [NSValue valueWithCGPoint:CGPointMake(view.center.x, view.center.y)],
                      [NSValue valueWithCGPoint:CGPointMake(view.center.x-5, view.center.y)],
                      [NSValue valueWithCGPoint:CGPointMake(view.center.x+5, view.center.y)],
                      [NSValue valueWithCGPoint:CGPointMake(view.center.x, view.center.y)],
                      nil];
    [keyAn setValues:array]; 
    NSArray *times = [[NSArray alloc] initWithObjects:
                      [NSNumber numberWithFloat:0.1f],
                      [NSNumber numberWithFloat:0.2f],
                      [NSNumber numberWithFloat:0.3f],
                      [NSNumber numberWithFloat:0.4f],
                      [NSNumber numberWithFloat:0.5f],
                      [NSNumber numberWithFloat:0.6f],
                      [NSNumber numberWithFloat:0.7f],
                      [NSNumber numberWithFloat:0.8f],
                      [NSNumber numberWithFloat:0.9f],
                      [NSNumber numberWithFloat:1.0f],
                      nil];
    [keyAn setKeyTimes:times];
    [view.layer addAnimation:keyAn forKey:@"TextAnim"];
}