kCGImagePropertyIPTC关键字问题

Question

我正在开发一个 iPhone 应用程序，我想在其中使用 ImageIO 框架设置图像的关键字。

以下是我用于设置关键字的代码片段。问题是它没有将关键字应用于图像元数据。有人可以帮我找到这里的问题吗？

NSMutableDictionary *iptcDictionary = [NSDictionary dictionaryWithObject: [NSArray arrayWithObject: @"Test"] 
    forKey:(NSString *)kCGImagePropertyIPTCKeywords];

NSDictionary *newImageProperties = [NSDictionary dictionaryWithObject:iptcDictionary 
    forKey:(NSString *)kCGImagePropertyIPTCDictionary];

CGImageSourceRef imageSource=CGImageSourceCreateWithURL((CFURLRef)imageURL, nil);  //imageURL is URL of source image

CGImageDestinationRef imageDestination = CGImageDestinationCreateWithData(    
    (CFMutableDataRef)newImageFileData, CGImageSourceGetType(imageSource), 1,NULL);

CGImageDestinationAddImageFromSource(imageDestination, imageSource, 0, 
    (CFDictionaryRef) newImageProperties);

if (CGImageDestinationFinalize(imageDestination)) {
    [newImageFileData writeToFile:imagePath atomically:YES]; //imagePath is the path of the destination image with new metadata
}