使UIImage的一部分透明，或裁剪该区域

Question

我有一个像这样的UIImage：

我想删除中间的一个矩形，就像这样：

Answer 1

打孔的最简单方法是添加图层蒙版。

• #import <QuartzCore/QuartzCore.h>

• 创建要剪辑的路径（您想要穿过的矩形）

  UIBezierPath *maskPath = [UIBezierPath bezierPathWithRect:yourView.bounds];
  [maskPath appendPath:[UIBezierPath bezierPathWithRect:rectToPunchThroughTheView]];
  

• 然后创建一个遮罩层并将其添加到您的视图中 - CAShapeLayer将允许您定义任何路径

  CAShapeLayer *maskLayer = [CAShapeLayer layer];
  maskLayer.fillRule  = kCAFillRuleEvenOdd;
  maskLayer.fillColor = [UIColor blackColor].CGColor;
  maskLayer.path      = maskPath.CGPath;
  
  yourView.layer.mask = maskLayer;
  

Answer 2

我会创建一个UIImage类别，并使用不同的rects裁剪图像两次。

这是我刚刚在我的UIImage类别中添加的方法，它符合我的需求：

- (UIImage *)cropWithRect:(CGRect)rect {

    // If run on a retina device scale is 2 else 1
    rect = CGRectMake(rect.origin.x * self.scale,
                      rect.origin.y * self.scale,
                      rect.size.width * self.scale,
                      rect.size.height * self.scale);

    CGImageRef imgRf = CGImageCreateWithImageInRect(self.CGImage, rect);
    UIImage *croppedImage = [UIImage imageWithCGImage:imageRef 
                                                scale:self.scale
                                          orientation:self.imageOrientation];
    CGImageRelease(imageRef);

    return croppedImage;

}

Answer 3

你可以这样做

        CGRect fullimageRect;
        CGRect upperRect;
        CGRect lowerRect;

        UIImage *upperImage;
        UIImage *lowerImage;
        UIImage *finalImage;

        UIGraphicsBeginImageContext(upperRect.size);
        [[UIImage imageNamed:@"yourimage.png"] drawInRect:lowerRect];
        upperImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();


        UIGraphicsBeginImageContext(lowerRect.size);
        [[UIImage imageNamed:@"yourimage.png"] drawInRect:lowerRect];
        lowerImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();

        NSLog(@"%@",upperImage);
        NSLog(@"%@",lowerImage);


        UIGraphicsBeginImageContext(fullimageRect.size);
        [upperImage drawInRect:upperRect];
        [lowerImage drawInRect:lowerRect];
        finalImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();

        NSLog(@"%@",finalImage);