CAMediaTimingFunction ：https://github.com/YouXianMing/Tween-o-Matic-CN?spm=5176.100239.blogcont29568.8.hA2dRk 设置动画的速度变化
- (void)viewDidLoad {
[super viewDidLoad];
// 初始化layer
CALayer *layer = [CALayer layer];
layer.frame = CGRectMake(50, 50, 200, 2);
layer.backgroundColor = [UIColor blackColor].CGColor;
// 终点位置
CGPoint endPosition = CGPointMake(layer.position.x, layer.position.y + 200);
// 动画
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"position"];
animation.fromValue = [NSValue valueWithCGPoint:layer.position];
animation.toValue = [NSValue valueWithCGPoint:endPosition];
animation.timingFunction = [CAMediaTimingFunction functionWithControlPoints:0.20 :0.03 :0.13 :1.00];
layer.position = endPosition;
animation.duration = 1.f;
// 添加动画
[layer addAnimation:animation forKey:nil];
// 添加layer
[self.view.layer addSublayer:layer];
}
