ios拓展32-图片圆角

1.直接设置

iOS9之后不会触发离屏渲染（off-screen-rendering）

imgView.layer.cornerRadius = 50;
imgView..layer.masksToBounds= YES;

2.对图片重绘

给UIImage添加生成圆角图片的分类,性能最好

- (UIImage *)imageWithCornerRadius:(CGFloat)radius {
    CGRect rect = CGRectMake(0, 0, self.size.width, self.size.height);
//开启图片上下文
    UIGraphicsBeginImageContextWithOptions(self.size, NO, UIScreen.mainScreen.scale);
// 画圆
    CGContextAddPath(UIGraphicsGetCurrentContext(),[UIBezierPath bezierPathWithRoundedRect:rect cornerRadius:radius].CGPath);
//裁剪
    CGContextClip(UIGraphicsGetCurrentContext());
    //绘制
    [self drawInRect:rect];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return image;
}

3.使用CAShapeLayer,实际测试会有离屏渲染,

// 头像圆角
    UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:self.portarit.bounds byRoundingCorners:UIRectCornerAllCorners cornerRadii:self.portarit.bounds.size];
    CAShapeLayer *maskLayer = [[CAShapeLayer alloc]init];
    maskLayer.frame = self.portarit.bounds;
    maskLayer.path = maskPath.CGPath;
    self.portarit.layer.mask = maskLayer;

3.总结
图片圆角没什么难度,一般情况下用第1个方法就可以了, 不过当在tableView中最好使用第2个方法