UIViewPropertyAnimator是修改动画属性的核心类，它提供了中断动画、修改动画中间过程的功能；

- (void)viewDidLoad {
    [super viewDidLoad];
   
    UIView *redView = [[UIView alloc] init];
    redView.frame = CGRectMake(100, 100, 100, 100);
    redView.backgroundColor = [UIColor redColor];
    [self.view addSubview:redView];
    /*
     这是苹果提供的4中曲线
     UIViewAnimationCurveEaseInOut,         // slow at beginning and end
     UIViewAnimationCurveEaseIn,            // slow at beginning
     UIViewAnimationCurveEaseOut,           // slow at end
     UIViewAnimationCurveLinear,
     */
    UIViewPropertyAnimator *animator = [[UIViewPropertyAnimator alloc] initWithDuration:4 curve:UIViewAnimationCurveEaseIn animations:^{

        redView.transform = CGAffineTransformTranslate(redView.transform, 0, 100);
        
    }];
    self.animator = animator;
}

/**
 开始动画
 */
- (IBAction)startAnim:(UIButton *)sender {
    [self.animator startAnimation];
}

/**
 暂停动画
 */
- (IBAction)pauseAnim:(UIButton *)sender {
    [self.animator pauseAnimation];
}

/**
 继续动画
 */
- (IBAction)continueAnim:(UIButton *)sender {
    UISpringTimingParameters *param = [[UISpringTimingParameters alloc] initWithDampingRatio:0.1];
    [self.animator continueAnimationWithTimingParameters:param durationFactor:1];
}

/**
 停止动画
 */
- (IBAction)stopAnim:(UIButton *)sender {
    [self.animator stopAnimation:true];
}