//1.设置圆角
self.imageView.layer.masksToBounds = YES;
//2.设置圆形图案半径
self.imageView.layer.cornerRadius = self.imageView.layer.bounds.size.width *0.5;
//3.设置边框颜色
self.imageView.layer.borderColor = [UIColor redColor].CGColor;
//4.设置边框宽度
self.imageView.layer.borderWidth = 5;