1. 画圆角

  （1）传统的圆角设置方式 imageView.clipsToBounds = YES;

                                            imageView.layer.cornerRadius = 4;

    （2）使用UIBezierPath（此处self指的是View）

                UIBezierPath * path = [UIBezierPath bezierPathWithRoundedRect:self.bounds byRoundingCorners:UIRectCornerAllCorners cornerRadii:CGSizeMake(corner, corner)];

CAShapeLayer * layer = [CAShapeLayer new];

layer.frame = self.bounds;

layer.path = path.CGPath;

self.layer.mask = layer;

2.设置圆角之后我们会发现再设置阴影时无效果，此时我们需要创建一个view把imageview加载在view上，设置view的shadow

imageView.layer.shadowColor = [UIColor blackColor].CGColor;

imageView.layer.shadowOffset = CGSizeMake(5, 5);//设置阴影的便宜位置

imageView.layer.shadowOpacity = 0.8;

imageView.layer.shadowRadius = 5;