-(void)drawRect:(CGRect)rect{      CGContextRef ctx=UIGraphicsGetCurrentContext();      CGContextBeginPath(ctx);      CGContextAddRect(ctx, CGRectMake(100, 100, 100, 100));      CGContextClip(ctx);//裁减，相对的CGContextClearRect是只留下矩形外面的      CGContextBeginPath(ctx);      CGContextAddRect(ctx, CGRectMake(0, 0, rect.size.width,   rect.size.height));      [[UIColor brownColor]setFill];      CGContextFillPath(ctx);}

 

//绘制路径   CGMutablePathRef path=  CGPathCreateMutable();    CGPathMoveToPoint(path, NULL, 20, 20);    CFRelease(path); //

CGContextAddPath(ctx, path1);

 

#pragma mark --截图-(void)jitu{    //切换到图片上下问    UIGraphicsBeginImageContext(self.frame.size);    //将view绘制到图形上下文中    [self.layer renderInContext:UIGraphicsGetCurrentContext()];    //将截屏保存到相册    UIImage *newImage=UIGraphicsGetImageFromCurrentImageContext();        UIImageWriteToSavedPhotosAlbum(newImage,self, @selector(image:didFinishSavingWithError:contextInfo:), nil);}- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo {         if (error) {             NSLog(@"保存失败，请检查是否拥有相关的权限");             }else                 {                     NSLog(@"保存成功！");                     }     }

 

//绘制图片   UIGraphicsBeginImageContextWithOptions( CGSizeMake(200, 200), NO, 0);             //1.获取bitmap上下文             CGContextRef ctx = UIGraphicsGetCurrentContext();             //2.绘图(画一个圆)             CGContextAddEllipseInRect(ctx, CGRectMake(0, 0, 100, 100));             //3.渲染             CGContextStrokePath(ctx);             //4.获取生成的图片             UIImage *image=UIGraphicsGetImageFromCurrentImageContext();             //5.显示生成的图片到imageview//             self.iv.image=image;             //6.保存绘制好的图片到文件中             //先将图片转换为二进制数据，然后再将图片写到文件中         //    UIImageJPEGRepresentation(image, 1); //第二个参数为保存的图片的效果             NSData *data=UIImagePNGRepresentation(image);             [data writeToFile:@"/Users/liyang/Library/Developer/abc.png" atomically:YES];