iOS - 视图抖动效果

实现视图抖动效果的思路

一、首先，如何让视图发生位移

UIView中定义了transform属性，其类型为CGAffineTransform，默认是CGAffineTransformIdentity
transform 改变位置/尺寸/旋转角度，且是在原有transform的基础上改变
①创建“基于控件初始位置”的形变

  CGAffineTransformMakeTranslation（平移）
  CGAffineTransformMakeScale（缩放）
  CGAffineTransformMakeRotation（旋转）

②创建“基于transform参数”的形变

  CGAffineTransformTranslate
  CGAffineTransformScale
  CGAffineTransformRotate

补充：
在OC中，所有跟角度相关的数值，都是弧度值，180° = M_PI
正数表示顺时针旋转
负数表示逆时针旋转

二、如何让视图的位移形成反复动画

在UIViewAnimationWithBlocks中提供了一系列的视图动画
我们最常用的也就是下面三种：

+ (void)animateWithDuration:(NSTimeInterval)duration delay:(NSTimeInterval)delay options:(UIViewAnimationOptions)options animations:(void (^)(void))animations completion:(void (^ __nullable)(BOOL finished))completion NS_AVAILABLE_IOS(4_0);

+ (void)animateWithDuration:(NSTimeInterval)duration animations:(void (^)(void))animations completion:(void (^ __nullable)(BOOL finished))completion NS_AVAILABLE_IOS(4_0); // delay = 0.0, options = 0

+ (void)animateWithDuration:(NSTimeInterval)duration animations:(void (^)(void))animations NS_AVAILABLE_IOS(4_0); // delay = 0.0, options = 0, completion = NULL

其中UIViewAnimationOptions枚举值如下：

typedef NS_OPTIONS(NSUInteger, UIViewAnimationOptions) {
    UIViewAnimationOptionLayoutSubviews            = 1 <<  0, // 提交动画的时候布局子控件，表示子控件将和父控件一同动画
    UIViewAnimationOptionAllowUserInteraction      = 1 <<  1, // 动画时允许用户交互
    UIViewAnimationOptionBeginFromCurrentState     = 1 <<  2, // 从当前状态开始动画，而不是初始状态
    UIViewAnimationOptionRepeat                    = 1 <<  3, // 动画无限重复
    UIViewAnimationOptionAutoreverse               = 1 <<  4, // 在动画可以重复的前提下，可执行动画回路
    UIViewAnimationOptionOverrideInheritedDuration = 1 <<  5, // 忽略外层动画嵌套的执行时间
    UIViewAnimationOptionOverrideInheritedCurve    = 1 <<  6, // 忽略外层动画嵌套的时间变化曲线
    UIViewAnimationOptionAllowAnimatedContent      = 1 <<  7, // animate contents (applies to transitions only)
    UIViewAnimationOptionShowHideTransitionViews   = 1 <<  8, // 用显隐的方式替代添加移除图层的动画效果
    UIViewAnimationOptionOverrideInheritedOptions  = 1 <<  9, // 忽略嵌套继承的选项
    
    ///时间函数曲线相关
    UIViewAnimationOptionCurveEaseInOut            = 0 << 16, // 时间曲线函数，由慢到快 default
    UIViewAnimationOptionCurveEaseIn               = 1 << 16, // 时间曲线函数，由慢到特别快
    UIViewAnimationOptionCurveEaseOut              = 2 << 16, //时间曲线函数，由快到慢
    UIViewAnimationOptionCurveLinear               = 3 << 16, //时间曲线函数，匀速
    
    ///转场动画相关的
    UIViewAnimationOptionTransitionNone            = 0 << 20, //无转场动画 default
    UIViewAnimationOptionTransitionFlipFromLeft    = 1 << 20, //转场从左翻转
    UIViewAnimationOptionTransitionFlipFromRight   = 2 << 20, //转场从右翻转
    UIViewAnimationOptionTransitionCurlUp          = 3 << 20, //上卷转场
    UIViewAnimationOptionTransitionCurlDown        = 4 << 20, //下卷转场
    UIViewAnimationOptionTransitionCrossDissolve   = 5 << 20, //转场交叉消失
    UIViewAnimationOptionTransitionFlipFromTop     = 6 << 20, //转场从上翻转
    UIViewAnimationOptionTransitionFlipFromBottom  = 7 << 20, //转场从下翻转

    UIViewAnimationOptionPreferredFramesPerSecondDefault     = 0 << 24,
    UIViewAnimationOptionPreferredFramesPerSecond60          = 3 << 24,
    UIViewAnimationOptionPreferredFramesPerSecond30          = 7 << 24,
    
} NS_ENUM_AVAILABLE_IOS(4_0);

补充：关于最后一组转场动画它一般是用在这个方法中的：

    [UIView transitionFromView: toView: duration: options: completion:^(BOOL finished) {}];

三、基础了解完毕，上代码

+ (void)shakeView:(UIView*)viewToShake {
    // 偏移值
    CGFloat t = 3.0;
    // 左摇
    CGAffineTransform translateLeft =CGAffineTransformTranslate(CGAffineTransformIdentity,-t,0.0);
    // 右晃
    CGAffineTransform translateRight  =CGAffineTransformTranslate(CGAffineTransformIdentity, t,0.0);
    // 执行动画 重复动画且执行动画回路
    viewToShake.transform = translateLeft;
    [UIView animateWithDuration:0.07 delay:0.0 options:UIViewAnimationOptionAutoreverse | UIViewAnimationOptionRepeat animations:^{
        // 设置重复次数 repeatCount为float
        [UIView setAnimationRepeatCount:2.0];
        viewToShake.transform = translateRight;
        
    } completion:^(BOOL finished){
        if(finished){
            // 从视图当前状态回到初始状态
            [UIView animateWithDuration:0.05 delay:0.0 options:UIViewAnimationOptionBeginFromCurrentState animations:^{
                viewToShake.transform =CGAffineTransformIdentity;
            } completion:NULL];
        }
    }];
}