問題設(shè)置圖像的exif數(shù)據(jù)我在iOS 4.1中使用新的ImageIO框架。我使用以下代碼成功檢索exif元數(shù)據(jù)：CFDictionaryRef metadataDict = CMGetAttachment(sampleBuffer, kCGImagePropertyExifDictionary , NULL);閱讀它，它似乎是有效的。保存圖像有效，但圖像中從不存在任何exif數(shù)據(jù)。    CGImageDestinationRef myImageDest = CGImageDestinationCreateWithURL((CFURLRef) docurl, kUTTypeJPEG, 1, NULL);     // Add the image to the destination using previously saved options.      CGImageDestinationAddImage(myImageDest, iref, NULL);     //add back exif     NSDictionary *props = [NSDictionary dictionaryWithObjectsAndKeys:                             [NSNumber numberWithFloat:.1], kCGImageDestinationLossyCompressionQuality,                            metadataDict, kCGImagePropertyExifDictionary, //the exif metadata                                                         nil];                           //kCGImagePropertyExifAuxDictionary     CGImageDestinationSetProperties(myImageDest, (CFDictionaryRef) props);     // Finalize the image destination.      bool status = CGImageDestinationFinalize(myImageDest);