块动画

- +(void)animateWithDuration:(NSTimeInterval)duration
animations:(void (^)(void))animations
completion:(void (^__nullable)(BOOL finished))completion;

- +(void)animateWithDuration:(NSTimeInterval)duration
animations:(void (^)(void))animations;

- +(void)animateWithDuration:(NSTimeInterval)**duration**
delay:(NSTimeInterval)**delay**
usingSpringWithDamping:(CGFloat)**dampingRatio**
initialSpringVelocity:(CGFloat)**velocity**
options:(UIViewAnimationOptions)**options**
animations:(void (^)(void))**animations**
completion:(void (^__nullable)(BOOL finished))**completion**;
- duration : 动画时间
- delay : 延迟时间
- dampingRatio : 阻尼系数(弹性) 越小越弹
- velocity : 速率
- options : 选项
- animations : 做动画的代码块
- completion : 动画完成的代码块 "回调"