objective-c - 使 UIImageView 变灰

Question

我正在使用 AFNetworking 库中的 setImageWithUrl 在表格单元格中设置 UImageViews，但我需要图像为灰度...有什么方法可以做到这一点。我尝试了一些 UIImage 灰度转换器，但我猜它们不起作用，因为我正在设置尚未下载的内容。

Answer 1

试试这个方法:

- (UIImage *)convertImageToGrayScale:(UIImage *)image
{
  // Create image rectangle with current image width/height
  CGRect imageRect = CGRectMake(0, 0, image.size.width, image.size.height);

  // Grayscale color space
  CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray();

  // Create bitmap content with current image size and grayscale colorspace
  CGContextRef context = CGBitmapContextCreate(nil, image.size.width, image.size.height, 8, 0, colorSpace, kCGImageAlphaNone);

  // Draw image into current context, with specified rectangle
  // using previously defined context (with grayscale colorspace)
  CGContextDrawImage(context, imageRect, [image CGImage]);

  // Create bitmap image info from pixel data in current context
  CGImageRef imageRef = CGBitmapContextCreateImage(context);

  // Create a new UIImage object  
  UIImage *newImage = [UIImage imageWithCGImage:imageRef];

  // Release colorspace, context and bitmap information
  CGColorSpaceRelease(colorSpace);
  CGContextRelease(context);
  CFRelease(imageRef);

  // Return the new grayscale image
  return newImage;
}

我在这里找到它:http://mobiledevelopertips.com/graphics/convert-an-image-uiimage-to-grayscale.html