单独一个或几个角收缩
//核心动画
CGRect rect = CGRectMake(50, 100, 100, 100);
CAShapeLayer * shapeLayer = [CAShapeLayer layer];
shapeLayer.frame = rect;
shapeLayer.strokeColor = [[UIColor redColor] CGColor];
//圆形
//UIBezierPath * Bpath = [UIBezierPath bezierPathWithOvalInRect:rect];
//长方形
//UIBezierPath * Bpath = [UIBezierPath bezierPathWithRect:rect];
//圆角矩形
UIBezierPath * Bpath = [UIBezierPath bezierPathWithRoundedRect:rect cornerRadius:60];
//单独一个或几个角
//UIBezierPath * Bpath = [UIBezierPath bezierPathWithRoundedRect:rect byRoundingCorners:(UIRectCornerTopLeft) cornerRadii:(CGSize){ 50,50 }];
shapeLayer.path = Bpath.CGPath;
[self.view.layer addSublayer:shapeLayer];
