Po niezliczonych próbach i przesiewaniu każdej odpowiedzi SO + wynik google, zaskakuje mnie, że praca z EXIF ​​na iOS jest tak frustrująca.

Poniżej znajduje się roboczy kod z jego wynikami.

[[self stillImageOutput] captureStillImageAsynchronouslyFromConnection:videoConnection
    completionHandler:^(CMSampleBufferRef imageSampleBuffer, NSError *error)
    {
        NSData *imageNSData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer];

        CGImageSourceRef imgSource = CGImageSourceCreateWithData((__bridge_retained CFDataRef)imageNSData, NULL);

        //get all the metadata in the image
        NSDictionary *metadata = (__bridge NSDictionary *)CGImageSourceCopyPropertiesAtIndex(imgSource, 0, NULL);

        NSLog(@"original metadata Info: %@",metadata);

        //make the metadata dictionary mutable so we can add properties to it
        NSMutableDictionary *metadataAsMutable = [metadata mutableCopy];

        NSMutableDictionary *EXIFDictionary = [[metadataAsMutable objectForKey:(NSString *)kCGImagePropertyExifDictionary]mutableCopy];
        NSMutableDictionary *GPSDictionary = [[metadataAsMutable objectForKey:(NSString *)kCGImagePropertyGPSDictionary]mutableCopy];
        NSMutableDictionary *RAWDictionary = [[metadataAsMutable objectForKey:(NSString *)kCGImagePropertyRawDictionary]mutableCopy];

        if(!EXIFDictionary)
            EXIFDictionary = [[NSMutableDictionary dictionary] init];

        if(!GPSDictionary)
            GPSDictionary = [[NSMutableDictionary dictionary] init];

        if(!RAWDictionary)
            RAWDictionary = [[NSMutableDictionary dictionary] init];


        [GPSDictionary setObject:@"camera coord Latitude"
                         forKey:(NSString*)kCGImagePropertyGPSLatitude];
        [GPSDictionary setObject:@"camera coord Longitude"
                         forKey:(NSString*)kCGImagePropertyGPSLongitude];
        [GPSDictionary setObject:@"camera GPS Date Stamp"
                         forKey:(NSString*)kCGImagePropertyGPSDateStamp];
        [GPSDictionary setObject:@"camera direction (heading) in degrees"
                         forKey:(NSString*)kCGImagePropertyGPSImgDirection];

        [GPSDictionary setObject:@"subject coord Latitude"
                         forKey:(NSString*)kCGImagePropertyGPSDestLatitude];
        [GPSDictionary setObject:@"subject coord Longitude"
                         forKey:(NSString*)kCGImagePropertyGPSDestLongitude];

        [EXIFDictionary setObject:@"[S.D.] kCGImagePropertyExifUserComment"
                           forKey:(NSString *)kCGImagePropertyExifUserComment];

        [EXIFDictionary setValue:@"69 m" forKey:(NSString *)kCGImagePropertyExifSubjectDistance];


        //Add the modified Data back into the image’s metadata
        [metadataAsMutable setObject:EXIFDictionary forKey:(NSString *)kCGImagePropertyExifDictionary];
        [metadataAsMutable setObject:GPSDictionary forKey:(NSString *)kCGImagePropertyGPSDictionary];
        [metadataAsMutable setObject:RAWDictionary forKey:(NSString *)kCGImagePropertyRawDictionary];


        NSLog(@"metadataAsMutable Info: %@",metadataAsMutable);

        CFStringRef UTI = CGImageSourceGetType(imgSource); //this is the type of image (e.g., public.jpeg)

        //this will be the data CGImageDestinationRef will write into
        NSMutableData *newImageData = [NSMutableData data];

        CGImageDestinationRef destination = CGImageDestinationCreateWithData((__bridge CFMutableDataRef)newImageData, UTI, 1, NULL);

        if(!destination)
            NSLog(@"***Could not create image destination ***");

        //add the image contained in the image source to the destination, overidding the old metadata with our modified metadata
        CGImageDestinationAddImageFromSource(destination, imgSource, 0, (__bridge CFDictionaryRef) metadataAsMutable);

        //tell the destination to write the image data and metadata into our data object.
        //It will return false if something goes wrong
        BOOL success = NO;
        success = CGImageDestinationFinalize(destination);

        if(!success)
            NSLog(@"***Could not create data from image destination ***");

        CIImage *testImage = [CIImage imageWithData:newImageData];
        NSDictionary *propDict = [testImage properties];
        NSLog(@"Properties %@", propDict);

    }];

Który wyprowadza to:

2012-10-12 23:17:45.415 Waypointer[3120:907] original metadata Info: {
ColorModel = RGB;
DPIHeight = 72;
DPIWidth = 72;
Depth = 8;
Orientation = 1;
PixelHeight = 2448;
PixelWidth = 3264;
"{Exif}" =     {
    ApertureValue = "2.526069";
    BrightnessValue = "-4.410617";
    ColorSpace = 1;
    ComponentsConfiguration =         (
        1,
        2,
        3,
        0
    );
    ExifVersion =         (
        2,
        2,
        1
    );
    ExposureMode = 0;
    ExposureProgram = 2;
    ExposureTime = "0.06666667";
    FNumber = "2.4";
    Flash = 16;
    FlashPixVersion =         (
        1,
        0
    );
    FocalLenIn35mmFilm = 35;
    FocalLength = "4.28";
    ISOSpeedRatings =         (
        800
    );
    MeteringMode = 5;
    PixelXDimension = 3264;
    PixelYDimension = 2448;
    SceneCaptureType = 0;
    SensingMethod = 2;
    ShutterSpeedValue = "3.906905";
    SubjectArea =         (
        1631,
        1223,
        881,
        881
    );
    WhiteBalance = 0;
};
"{TIFF}" =     {
    Orientation = 1;
    ResolutionUnit = 2;
    XResolution = 72;
    YResolution = 72;
    "_YCbCrPositioning" = 1;
};
}

I to:

2012-10-12 23:17:45.421 Waypointer[3120:907] metadataAsMutable Info: {
ColorModel = RGB;
DPIHeight = 72;
DPIWidth = 72;
Depth = 8;
Orientation = 1;
PixelHeight = 2448;
PixelWidth = 3264;
"{Exif}" =     {
    ApertureValue = "2.526069";
    BrightnessValue = "-4.410617";
    ColorSpace = 1;
    ComponentsConfiguration =         (
        1,
        2,
        3,
        0
    );
    ExifVersion =         (
        2,
        2,
        1
    );
    ExposureMode = 0;
    ExposureProgram = 2;
    ExposureTime = "0.06666667";
    FNumber = "2.4";
    Flash = 16;
    FlashPixVersion =         (
        1,
        0
    );
    FocalLenIn35mmFilm = 35;
    FocalLength = "4.28";
    ISOSpeedRatings =         (
        800
    );
    MeteringMode = 5;
    PixelXDimension = 3264;
    PixelYDimension = 2448;
    SceneCaptureType = 0;
    SensingMethod = 2;
    ShutterSpeedValue = "3.906905";
    SubjectArea =         (
        1631,
        1223,
        881,
        881
    );
    SubjectDistance = "69 m";
    UserComment = "[S.D.] kCGImagePropertyExifUserComment";
    WhiteBalance = 0;
};
"{GPS}" =     {
    DateStamp = "camera GPS Date Stamp";
    DestLatitude = "subject coord Latitude";
    DestLongitude = "subject coord Longitude";
    ImgDirection = "camera direction (heading) in degrees";
    Latitude = "camera coord Latitude";
    Longitude = "camera coord Longitude";
};
"{Raw}" =     {
};
"{TIFF}" =     {
    Orientation = 1;
    ResolutionUnit = 2;
    XResolution = 72;
    YResolution = 72;
    "_YCbCrPositioning" = 1;
};
}

Po tym wszystkim to:

2012-10-12 23:17:47.131 Waypointer[3120:907] Properties {
ColorModel = RGB;
DPIHeight = 72;
DPIWidth = 72;
Depth = 8;
Orientation = 1;
PixelHeight = 2448;
PixelWidth = 3264;
"{Exif}" =     {
    ApertureValue = "2.526069";
    BrightnessValue = "-4.410617";
    ColorSpace = 1;
    ComponentsConfiguration =         (
        0,
        0,
        0,
        1
    );
    ExifVersion =         (
        2,
        2,
        1
    );
    ExposureMode = 0;
    ExposureProgram = 2;
    ExposureTime = "0.06666667";
    FNumber = "2.4";
    Flash = 16;
    FlashPixVersion =         (
        1,
        0
    );
    FocalLenIn35mmFilm = 35;
    FocalLength = "4.28";
    ISOSpeedRatings =         (
        800
    );
    MeteringMode = 5;
    PixelXDimension = 3264;
    PixelYDimension = 2448;
    SceneCaptureType = 0;
    SensingMethod = 2;
    ShutterSpeedValue = "3.906905";
    SubjectArea =         (
        1631,
        1223,
        881,
        881
    );
    UserComment = "[S.D.] kCGImagePropertyExifUserComment";
    WhiteBalance = 0;
};
"{JFIF}" =     {
    DensityUnit = 1;
    JFIFVersion =         (
        1,
        1
    );
    XDensity = 72;
    YDensity = 72;
};
"{TIFF}" =     {
    Orientation = 1;
    ResolutionUnit = 2;
    XResolution = 72;
    YResolution = 72;
    "_YCbCrPositioning" = 1;
};
}

Jak pokazuje przykład, można zobaczyć oryginalną metadane obrazu, jego modyfikację, a następnie jego ostateczny wynik.

Końcowy wynik jest tym, co mnie niepokoi, ponieważ bez względu na to, co robię, nie mogę trzymać zmodyfikowanych wartości!

Czy brakuje mi bardzo konkretnego formatu? Dlaczego iOS usuwa moje modyfikacje? Co muszę zrobić, aby dodać te dodatkowe wartości? Są wymienione w .header i zorientowane, że powinny być łatwo akceptowane.