如何将 UILabel 文本颜色设置为背景图像

Question

我想设计一个视图，其中UILabel 文本应保持透明，以便背景图像可以通过文本看到，即UILabel 的透明文本 随着移动UILabel，文字颜色应根据背景变化 图片 请帮帮我

UIImage *croppedImage=[self crop:self.demo.frame];

 self.demo.textColor=[UIColor colorWithPatternImage:croppedImage];

我正在裁剪演示大小的图像（UILabel）并设置其文本颜色 但图像得到双重像素化

Answer 1

通过传递准确的 LabelSize 来裁剪图像；

// get sub image
- (UIImage*) getSubImageFrom: (UIImage*) img WithRect: (CGRect) rect {

    UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();

    // translated rectangle for drawing sub image
    CGRect drawRect = CGRectMake(-rect.origin.x, -rect.origin.y, img.size.width, img.size.height);

    // clip to the bounds of the image context
    // not strictly necessary as it will get clipped anyway?
    CGContextClipToRect(context, CGRectMake(0, 0, rect.size.width, rect.size.height));

    // draw image
    [img drawInRect:drawRect];

    // grab image
    UIImage* subImage = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return subImage;
}