2018-07-04

后台绘制圆角图片

 - (void)setCircleImage
{
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        UIImage * circleImage = [image imageWithCircle];
        dispatch_async(dispatch_get_main_queue(), ^{
            imageView.image = circleImage;
        });
    });
}


#import "UIImage+Addtions.h"
@implementation UIImage (Addtions)
//返回一张圆形图片
- (instancetype)imageWithCircle
{
    UIGraphicsBeginImageContextWithOptions(self.size, NO, 0);
    UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(0, 0, self.size.width, self.size.height)];
    [path addClip];
    [self drawAtPoint:CGPointZero];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}

参考链接链接

iOS 离屏渲染优化(Offscreen Render)