Saving Geotag info with photo on iOS4.1

Question

I am having major issues trying to save a photo to camera roll with geotag info on iOS4.1. I am using following ALAssetsLibrary API:

- (void)writeImageDataTo         


        

Answer 1

After much searching I found and adapted this

This turns cclocation data into a suitable NSDictionary

 #import 

+(NSMutableDictionary *)updateExif:(CLLocation *)currentLocation{


    NSMutableDictionary* locDict = [[NSMutableDictionary alloc] init];


    CLLocationDegrees exifLatitude = currentLocation.coordinate.latitude;
    CLLocationDegrees exifLongitude = currentLocation.coordinate.longitude;

    [locDict setObject:currentLocation.timestamp forKey:(NSString*)kCGImagePropertyGPSTimeStamp];

    if (exifLatitude <0.0){
        exifLatitude = exifLatitude*(-1);
        [locDict setObject:@"S" forKey:(NSString*)kCGImagePropertyGPSLatitudeRef];
    }else{
        [locDict setObject:@"N" forKey:(NSString*)kCGImagePropertyGPSLatitudeRef];
    }
    [locDict setObject:[NSNumber numberWithFloat:exifLatitude] forKey:(NSString*)kCGImagePropertyGPSLatitude];

    if (exifLongitude <0.0){
        exifLongitude=exifLongitude*(-1);
        [locDict setObject:@"W" forKey:(NSString*)kCGImagePropertyGPSLongitudeRef];
    }else{
        [locDict setObject:@"E" forKey:(NSString*)kCGImagePropertyGPSLongitudeRef];
    }
    [locDict setObject:[NSNumber numberWithFloat:exifLongitude] forKey:(NSString*) kCGImagePropertyGPSLongitude];


    return [locDict autorelease];

}

Then I add it to the existing metadata that you get through the camera (which doesn't by default have the gps data)

I get the original metadata like this

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{  
    [imageMetaData setDictionary:[[info objectForKey:UIImagePickerControllerMediaMetadata] copy]];
}

then I add the gps dictionary the previous method produces.

[imageMetaData setObject:currentLocation forKey:(NSString*)kCGImagePropertyGPSDictionary];          

    [library writeImageToSavedPhotosAlbum:[viewImage CGImage] metadata:imageMetaData completionBlock:photoCompblock];