衰减动画
- (void)viewDidLoad {
[super viewDidLoad];
[self initCircleBtn];
}
- (void)initCircleBtn {
// 实例化手势，并最终将手势添加到圆形按钮上
UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(handlePan:)];
// 实例化圆形按钮
UIButton *circleBtn = [[UIButton alloc]init];
circleBtn.bounds = CGRectMake(0, 0, 100, 100);
circleBtn.center = self.view.center;
circleBtn.backgroundColor = [UIColor redColor];
circleBtn.layer.cornerRadius = CGRectGetWidth(circleBtn.frame) / 2;
[circleBtn addGestureRecognizer:pan];
[circleBtn addTarget:self action:@selector(handleDown:) forControlEvents:UIControlEventTouchDown];
[self.view addSubview:circleBtn];
}
- (void)handlePan:(UIPanGestureRecognizer *)recognizer {
CGPoint translation = [recognizer translationInView:self.view];
recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x, recognizer.view.center.y + translation.y);
[recognizer setTranslation:CGPointMake(0, 0) inView:self.view]; // 这句比较重要，因为handlePan:会持续调用，如果不把上一次调用该方法产生的位移清零，按钮会移动得很快
// 松手时，启动衰减动画
if (recognizer.state == UIGestureRecognizerStateEnded) {
CGPoint velocity = [recognizer velocityInView:self.view]; // 获取松手时，手势在控制器view的速度
POPDecayAnimation *popAnimation = [POPDecayAnimation animationWithPropertyNamed:kPOPLayerPosition]; // 实例化衰减动画，该衰减动画作用于Position
[popAnimation setVelocity:[NSValue valueWithCGPoint:velocity]]; // 设置衰减动画的初始速度
[recognizer.view pop_addAnimation:popAnimation forKey:@"suibian"]; // 添加衰减动画到圆形按钮
}
}