iOS View 抖动效果

在最近的项目中使用到View抖动的效果，就从StackOverflow搬运了一个在此记录一下。

- (void)earthquake:(UIView*)itemView {
    CGFloat t = 2.0;
    CGAffineTransform leftQuake  = CGAffineTransformTranslate(CGAffineTransformIdentity, t, 0);
    CGAffineTransform rightQuake = CGAffineTransformTranslate(CGAffineTransformIdentity, -t, 0); //水平晃动
    
    itemView.transform = leftQuake;  // starting point
    
    [UIView beginAnimations:@"earthquake" context:(__bridge void *)(itemView)];
    [UIView setAnimationRepeatAutoreverses:YES]; // 如果不加这一句 整个动画感觉不连贯
    [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;
    }
}