CGImageDestinationFinalize使用CGImageDestinationCopyImageSource失败

Question

我想复制一个uiimage并更改元数据，而不用重新编码图像，以便不会导致jpg工件（我知道下面的代码重新编码，但这只是为了它可以运行测试）。 CGImageDestinationCopyImageSource应该复制图像的来源而不用重新编码它，但是当我使用该函数时，它在CGImageDestinationFinalize时失败。我试图按照这个技术说明https://developer.apple.com/library/content/qa/qa1895/_index.html 任何想法为什么CGImageDestinationFinalize会失败，下面的代码？

-(NSData *)copyImageAndChangeMetaData:(UIImage *)image { 

    NSData *imageData = UIImageJPEGRepresentation(image, 1.0); 

    CGImageSourceRef source = CGImageSourceCreateWithData((__bridge CFDataRef)imageData, NULL); 
    NSLog(@" source: 0x%x", source); 
    if (source == NULL) { 
     NSLog(@" source is NULL"); 
    } 

    CFStringRef UTI = CGImageSourceGetType(source); 
    NSLog(@" UTI: %@", (__bridge NSString *)UTI); 
    if (UTI == NULL) { 
     NSLog(@" UTI is NULL"); 
    } 

    NSMutableData *dest_data = [NSMutableData data]; 
    CGImageDestinationRef destination = CGImageDestinationCreateWithData((__bridge CFMutableDataRef)dest_data, UTI, 1, NULL); 
    if (!destination) 
    { 
     NSLog(@"Image Data Error: Could not create image destination"); 
    } 

    CFMutableDictionaryRef metadata = CFDictionaryCreateMutable(kCFAllocatorDefault, 2, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks); 

    int orient = 8; 
    CFNumberRef orientRef = CFNumberCreate(kCFAllocatorDefault, kCFNumberIntType, &orient); 
    CFDictionarySetValue(metadata, kCGImageDestinationOrientation, orientRef); 

    CFStringRef dateStringRef = CFStringCreateWithCString(kCFAllocatorDefault, "2017-06-06T17:31:46Z", kCFStringEncodingASCII); 
    CFDictionarySetValue(metadata, kCGImageDestinationDateTime, dateStringRef); 

    CFErrorRef errorRef = nil; 
    if (!CGImageDestinationCopyImageSource(destination, source, metadata, &errorRef)) { 
     CFStringRef error_description = CFErrorCopyDescription(errorRef); 

     NSString *errorDescription = (__bridge NSString *)error_description; 
     NSLog(@"Image Data Error: Error copying image data: %@", errorDescription); 

     CFRelease(error_description); 
    } 

    BOOL success = NO; 
    success = CGImageDestinationFinalize(destination); 
    if (!success) 
    { 
     NSLog(@"Image Data Error: Could not finalize image"); 
    } 
    if (source != NULL) { 
     CFRelease(source); 
    } 

    if (destination != NULL) { 
     CFRelease(destination); 
    } 

    return dest_data; 
} 

Answer 1

根据文件<ImageIO/CGImageDestination.h>苹果HeaderDoc文档CGImageDestinationCopyImageSource()功能：）

CGImageDestinationFinalize（不应该被称为后 - 结果保存到目的地时，该函数返回。