在最近的項目中使用到View抖動的效果，就從StackOverflow搬運了一個在此記錄一下。

- (void)earthquake:(UIView*)itemView {
    CGFloat t = 2.0;
    CGAffineTransform leftQuake  = CGAffineTransformTranslate(CGAffineTransformIdentity, t, 0);
    CGAffineTransform rightQuake = CGAffineTransformTranslate(CGAffineTransformIdentity, -t, 0); //水平晃動
    
    itemView.transform = leftQuake;  // starting point
    
    [UIView beginAnimations:@"earthquake" context:(__bridge void *)(itemView)];
    [UIView setAnimationRepeatAutoreverses:YES]; // 如果不加這一句 整個動畫感覺不連貫
    [UIView setAnimationRepeatCount:5];
    [UIView setAnimationDuration:0.07];
    [UIView setAnimationDelegate:self];
    [UIView setAnimationDidStopSelector:@selector(earthquakeEnded:finished:context:)];
    
    itemView.transform = rightQuake; // end here & auto-reverse
    
    [UIView commitAnimations];
}

- (void)earthquakeEnded:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context {
    if ([finished boolValue]) {
        UIView* item = (__bridge UIView *)context;
        item.transform = CGAffineTransformIdentity;
    }
}