Question

How can we get Exif information from UIImage selected from UIImagePickerController?

I had done much R&D for this and got many replies but still failed to implement this.

I had gone through this this and this link

Please help me to solve this problem.

Thanks in advance..

Answer 1

I had found solution and got answer from here

From here We can get GPS info as well..

Amazing and thanks all for helping me to solve this problem.

UPDATE

This is another function that I had created myself, also return Exif data as well as GPS data and in this function we doesn’t need any third party library.. but you have to turn on location services for this. and use current latitude and longitude for that. so have to use CoreLocation.framework

//FOR CAMERA IMAGE

-(NSMutableData *)getImageWithMetaData:(UIImage *)pImage
{
    NSData* pngData =  UIImagePNGRepresentation(pImage);

    CGImageSourceRef source = CGImageSourceCreateWithData((CFDataRef)pngData, NULL);
    NSDictionary *metadata = (NSDictionary *) CGImageSourceCopyPropertiesAtIndex(source, 0, NULL);

    NSMutableDictionary *metadataAsMutable = [[metadata mutableCopy]autorelease];
    [metadata release];

    //For GPS Dictionary
    NSMutableDictionary *GPSDictionary = [[[metadataAsMutable objectForKey:(NSString *)kCGImagePropertyGPSDictionary]mutableCopy]autorelease];
    if(!GPSDictionary) 
        GPSDictionary = [NSMutableDictionary dictionary];

    [GPSDictionary setValue:[NSNumber numberWithDouble:currentLatitude] forKey:(NSString*)kCGImagePropertyGPSLatitude];
    [GPSDictionary setValue:[NSNumber numberWithDouble:currentLongitude] forKey:(NSString*)kCGImagePropertyGPSLongitude];

    NSString* ref;
    if (currentLatitude <0.0)
        ref = @"S"; 
    else
        ref =@"N";  
    [GPSDictionary setValue:ref forKey:(NSString*)kCGImagePropertyGPSLatitudeRef];

    if (currentLongitude <0.0)
        ref = @"W"; 
    else
        ref =@"E";  
    [GPSDictionary setValue:ref forKey:(NSString*)kCGImagePropertyGPSLongitudeRef];

    [GPSDictionary setValue:[NSNumber numberWithFloat:location.altitude] forKey:(NSString*)kCGImagePropertyGPSAltitude];

    //For EXIF Dictionary
    NSMutableDictionary *EXIFDictionary = [[[metadataAsMutable objectForKey:(NSString *)kCGImagePropertyExifDictionary]mutableCopy]autorelease];
    if(!EXIFDictionary) 
        EXIFDictionary = [NSMutableDictionary dictionary];

    [EXIFDictionary setObject:[NSDate date] forKey:(NSString*)kCGImagePropertyExifDateTimeOriginal];
    [EXIFDictionary setObject:[NSDate date] forKey:(NSString*)kCGImagePropertyExifDateTimeDigitized];

    //add our modified EXIF data back into the image’s metadata
    [metadataAsMutable setObject:EXIFDictionary forKey:(NSString *)kCGImagePropertyExifDictionary];
    [metadataAsMutable setObject:GPSDictionary forKey:(NSString *)kCGImagePropertyGPSDictionary];

    CFStringRef UTI = CGImageSourceGetType(source);

    NSMutableData *dest_data = [NSMutableData data];
    CGImageDestinationRef destination = CGImageDestinationCreateWithData((CFMutableDataRef)dest_data, UTI, 1, NULL);

    if(!destination)
        dest_data = [[pngData mutableCopy] autorelease];
    else 
    {
        CGImageDestinationAddImageFromSource(destination, source, 0, (CFDictionaryRef) metadataAsMutable);
        BOOL success = CGImageDestinationFinalize(destination);
        if(!success)
            dest_data = [[pngData mutableCopy] autorelease];
    }

    if(destination)
        CFRelease(destination);

    CFRelease(source);

    return dest_data;
}

//FOR PHOTO LIBRARY IMAGE

-(NSMutableData *)getImagedataPhotoLibrary:(NSDictionary *)pImgDictionary andImage:(UIImage *)pImage
{
    NSData* data = UIImagePNGRepresentation(pImage);

    CGImageSourceRef source = CGImageSourceCreateWithData((CFDataRef)data, NULL);
    NSMutableDictionary *metadataAsMutable = [[pImgDictionary mutableCopy]autorelease];

    CFStringRef UTI = CGImageSourceGetType(source);

    NSMutableData *dest_data = [NSMutableData data];

    //For Mutabledata
    CGImageDestinationRef destination = CGImageDestinationCreateWithData((CFMutableDataRef)dest_data, UTI, 1, NULL);

    if(!destination)
        dest_data = [[data mutableCopy] autorelease];
    else 
    {
        CGImageDestinationAddImageFromSource(destination, source, 0, (CFDictionaryRef) metadataAsMutable);
        BOOL success = CGImageDestinationFinalize(destination);
        if(!success)
            dest_data = [[data mutableCopy] autorelease];
    }
    if(destination)
        CFRelease(destination);

    CFRelease(source);

    return dest_data;
}

and We will retrieve that data like this

//FOR CAMERA IMAGE
NSData *originalImgData = [self getImageWithMetaData:imgOriginal];

//FOR PHOTO LIBRARY IMAGE
[self getImagedataPhotoLibrary:[[myasset defaultRepresentation] metadata] andImage:imgOriginal];

For all of this you should have to Import AssetsLibrary.framework and ImageIO.framework.