iOS高性能设置圆角

自建一个分类可以设置。

-(void)cornerImageWithSize:(CGSize)size fillColor:(UIColor *)fillColor completion:(void(^)(UIImage *resultImage))completion;

-(void)cornerImageWithSize:(CGSize)size fillColor:(UIColor *)fillColor completion:(void (^)(UIImage *))completion{
    dispatch_async(dispatch_get_global_queue(0, 0), ^{
        //1.利用绘图建立上下文
        UIGraphicsBeginImageContextWithOptions(size, YES, 0);
        CGRect rect = CGRectMake(0, 0, size.width, size.height);
        
        //2.建立填充颜色
        [fillColor setFill];
        UIRectFill(rect);
        
        //3.利用 贝塞尔路径 裁切 效果
        UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:rect];
        [path addClip];
        
        //4.绘制图像
        [self drawInRect:rect];
        
        //5.取得结果
        UIImage *result = UIGraphicsGetImageFromCurrentImageContext();
        
        //6.关闭上下文
        UIGraphicsEndImageContext();
        
        dispatch_async(dispatch_get_main_queue(), ^{
            if (completion != nil) {
                completion(result);
            }
        });
    });
}