GPS value pulled from iOS image is not showing proper Positive or Negative

Question

I am developing an iPhone app which will pull the GPS data from a photo that is taken. I have everything working pretty well for this function, but I have noticed that the GPS data being returned is not showing the proper + or - to the coordinate values. For example, I get this output in the log:

"{GPS}" =     {
    Altitude = "33.0329";
    DOP = 65;
    Latitude = "64.84069";
    LatitudeRef = N;
    Longitude = "32.41367";
    LongitudeRef = W;
    TimeStamp = "2014:01:04 14:47:01";
};

When I take the latitude and longitude on and use a reverse geolocation mapping, I get some place on the other side of the world. After looking into it, I see that the value:

Longitude = "32.41367";

should be:

Longitude = "-32.41367";

It was simply missing the negative. Any ideas as to why this may be happening? Here are some code samples that are building the above output:

    UIImage *image =  [info objectForKey:UIImagePickerControllerOriginalImage];
    NSData *jpeg = UIImageJPEGRepresentation(image,image.scale);
    CGImageSourceRef source = CGImageSourceCreateWithData((__bridge CFDataRef)jpeg, NULL);
    NSDictionary *metadata = (__bridge NSDictionary *)CGImageSourceCopyPropertiesAtIndex(source,0,NULL);
    NSMutableDictionary *mutableMetadata = [metadata mutableCopy];

    [mutableMetadata setLocation:self.currentLocation];

    CFStringRef UTI = CGImageSourceGetType(source);
    NSMutableData *data = [NSMutableData data];
    CGImageDestinationRef destination = CGImageDestinationCreateWithData((__bridge CFMutableDataRef) data, UTI, 1, NULL);
    CGImageDestinationAddImageFromSource(destination,source, 0, (__bridge CFDictionaryRef) mutableMetadata);
    BOOL success = CGImageDestinationFinalize(destination);

    NSLog(@"This is the log value that was referenced above: %@",mutableMetadata);

Answer 1

N and E have positive values S and W have negative values

However Google Maps knows how to map these if you just put the references in the coordinates. For example in Google Maps (50.53467,-100.45646) equals N50.53467W100.45646

Answer 2

Just a guess, but LongitudeRef = W might means negative. Seeing that westward longitude has negative values.

Answer 3

Martijn is correct lat lon values are more often written as N30.xxx and E97.xxx The letter represents the hemisphere. When converted to decimal degrees the NSEW are converted to +/-. Not sure why but it seem Google choose to convert the GPS output, which is likely in NMEA using HDD.MMMMM and kept the hemisphere character.