How to write exif metadata to an image (not the camera roll, just a UIImage or JPEG)

Question

I am aware of how to save metadata using ALAssets. But, I want to save an image, or upload it somewhere, with exif intact. I have exif data as an NSDictionary. But how can I inject it properly into a UIImage (or probably an NSData JPEG representation)?

[This answer](http://stackoverflow.com/questions/1238838/uiimagepickercontroller-and-extracting-exif-data-from-existing-photos) might be of help to you. — user1118321, Jan 25 '12 at 17:05

score 19 · Answer 1 · answered Apr 08 '14 at 20:30

I am using UIImagePickerController to get the image from the camera and my flow is a bit different than the one described by Chiquis. Here it is:

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
    UIImage *image = info[@"UIImagePickerControllerOriginalImage"];
    NSString *fullPhotoFilename = ...; // generate the photo name and path here
    NSData *photoData = [UIImage taggedImageData:image.jpegData metadata:info[@"UIImagePickerControllerMediaMetadata"] orientation:image.imageOrientation];
    [photoData writeToFile:fullPhotoFilename atomically:YES];
}

And using a UIImage category to put combine the image data with its metadata:

#import <ImageIO/ImageIO.h>
#import "UIImage+Tagging.h"
#import "LocationHelper.h"

@implementation UIImage (Tagging)

+ (NSData *)writeMetadataIntoImageData:(NSData *)imageData metadata:(NSMutableDictionary *)metadata {
    // create an imagesourceref
    CGImageSourceRef source = CGImageSourceCreateWithData((__bridge CFDataRef) imageData, NULL);

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

    // create a new data object and write the new image into it
    NSMutableData *dest_data = [NSMutableData data];
    CGImageDestinationRef destination = CGImageDestinationCreateWithData((__bridge CFMutableDataRef)dest_data, UTI, 1, NULL);
    if (!destination) {
        NSLog(@"Error: 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, source, 0, (__bridge CFDictionaryRef) metadata);
    BOOL success = NO;
    success = CGImageDestinationFinalize(destination);
    if (!success) {
        NSLog(@"Error: Could not create data from image destination");
    }
    CFRelease(destination);
    CFRelease(source);
    return dest_data;
}

+ (NSData *)taggedImageData:(NSData *)imageData metadata:(NSDictionary *)metadata orientation:(UIImageOrientation)orientation {
    CLLocationManager *locationManager = [CLLocationManager new];
    CLLocation *location = [locationManager location];
    NSMutableDictionary *newMetadata = [NSMutableDictionary dictionaryWithDictionary:metadata];
    if (!newMetadata[(NSString *)kCGImagePropertyGPSDictionary] && location) {
        newMetadata[(NSString *)kCGImagePropertyGPSDictionary] = [LocationHelper gpsDictionaryForLocation:location];
    }

    // Reference: http://sylvana.net/jpegcrop/exif_orientation.html
    int newOrientation;
    switch (orientation) {
        case UIImageOrientationUp:
            newOrientation = 1;
            break;

        case UIImageOrientationDown:
            newOrientation = 3;
            break;

        case UIImageOrientationLeft:
            newOrientation = 8;
            break;

        case UIImageOrientationRight:
            newOrientation = 6;
            break;

        case UIImageOrientationUpMirrored:
            newOrientation = 2;
            break;

        case UIImageOrientationDownMirrored:
            newOrientation = 4;
            break;

        case UIImageOrientationLeftMirrored:
            newOrientation = 5;
            break;

        case UIImageOrientationRightMirrored:
            newOrientation = 7;
            break;

        default:
            newOrientation = -1;
    }
    if (newOrientation != -1) {
        newMetadata[(NSString *)kCGImagePropertyOrientation] = @(newOrientation);
    }
    NSData *newImageData = [self writeMetadataIntoImageData:imageData metadata:newMetadata];
    return newImageData;
}

And finally, here is the method I am using to generate the needed GPS dictionary:

+ (NSDictionary *)gpsDictionaryForLocation:(CLLocation *)location {
    NSTimeZone      *timeZone   = [NSTimeZone timeZoneWithName:@"UTC"];
    NSDateFormatter *formatter  = [[NSDateFormatter alloc] init];
    [formatter setTimeZone:timeZone];
    [formatter setDateFormat:@"HH:mm:ss.SS"];

    NSDictionary *gpsDict = @{(NSString *)kCGImagePropertyGPSLatitude: @(fabs(location.coordinate.latitude)),
                          (NSString *)kCGImagePropertyGPSLatitudeRef: ((location.coordinate.latitude >= 0) ? @"N" : @"S"),
                          (NSString *)kCGImagePropertyGPSLongitude: @(fabs(location.coordinate.longitude)),
                          (NSString *)kCGImagePropertyGPSLongitudeRef: ((location.coordinate.longitude >= 0) ? @"E" : @"W"),
                          (NSString *)kCGImagePropertyGPSTimeStamp: [formatter stringFromDate:[location timestamp]],
                          (NSString *)kCGImagePropertyGPSAltitude: @(fabs(location.altitude)),
                          };
    return gpsDict;
}

Hope it helps someone. Thanks to Gustavo Ambrozio, Chiquis and several others SO members I was able to piece it together and use it in my project.

Excellent job, this is the only working solution that works beautifully with ALAssets. — Michael, Sep 28 '15 at 12:29
Thanks. In addition to setting the time, I also had to set the date. This just required a UTC date formatter with the format "yyyy:MM:dd" and a key of kCGImagePropertyGPSDateStamp. — Ian, Sep 12 '16 at 12:31
@dchakarov: Can we set GPS in DMS(Degree Minutes, Seconds) format? However I can able to sent GPS in Decimal format, Now I need it in DMS format. — Vijay, Oct 16 '18 at 11:42

score 16 · Accepted Answer · edited May 23 '17 at 12:02

UIImage does not contain metadata information (it is stripped). So if you want to save it without using the imagepicker method (not in camera roll):

Follow the answer here to write to a file with the metadata intact:

Problem setting exif data for an image

no idea why would this be downvoted but here is the method:

In this case im getting the image through AVFoundation and this is what goes in the

[[self stillImageOutput] captureStillImageAsynchronouslyFromConnection:videoConnection 
                                                     completionHandler:^(CMSampleBufferRef imageSampleBuffer, NSError *error) 
{
    // code here
}

block code:

    CFDictionaryRef metaDict = CMCopyDictionaryOfAttachments(NULL, imageSampleBuffer, kCMAttachmentMode_ShouldPropagate);

    CFMutableDictionaryRef mutable = CFDictionaryCreateMutableCopy(NULL, 0, metaDict);

    // Create formatted date
    NSTimeZone      *timeZone   = [NSTimeZone timeZoneWithName:@"UTC"];
    NSDateFormatter *formatter  = [[NSDateFormatter alloc] init]; 
    [formatter setTimeZone:timeZone];
    [formatter setDateFormat:@"HH:mm:ss.SS"];

    // Create GPS Dictionary
    NSDictionary *gpsDict   = [NSDictionary dictionaryWithObjectsAndKeys:
                               [NSNumber numberWithFloat:fabs(loc.coordinate.latitude)], kCGImagePropertyGPSLatitude
                               , ((loc.coordinate.latitude >= 0) ? @"N" : @"S"), kCGImagePropertyGPSLatitudeRef
                               , [NSNumber numberWithFloat:fabs(loc.coordinate.longitude)], kCGImagePropertyGPSLongitude
                               , ((loc.coordinate.longitude >= 0) ? @"E" : @"W"), kCGImagePropertyGPSLongitudeRef
                               , [formatter stringFromDate:[loc timestamp]], kCGImagePropertyGPSTimeStamp
                               , [NSNumber numberWithFloat:fabs(loc.altitude)], kCGImagePropertyGPSAltitude
                               , nil];  

    // The gps info goes into the gps metadata part

    CFDictionarySetValue(mutable, kCGImagePropertyGPSDictionary, (__bridge void *)gpsDict);

    // Here just as an example im adding the attitude matrix in the exif comment metadata

    CMRotationMatrix m = att.rotationMatrix;
    GLKMatrix4 attMat = GLKMatrix4Make(m.m11, m.m12, m.m13, 0, m.m21, m.m22, m.m23, 0, m.m31, m.m32, m.m33, 0, 0, 0, 0, 1);

    NSMutableDictionary *EXIFDictionary = (__bridge NSMutableDictionary*)CFDictionaryGetValue(mutable, kCGImagePropertyExifDictionary);

    [EXIFDictionary setValue:NSStringFromGLKMatrix4(attMat) forKey:(NSString *)kCGImagePropertyExifUserComment];

    CFDictionarySetValue(mutable, kCGImagePropertyExifDictionary, (__bridge void *)EXIFDictionary);

    NSData *jpeg = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer] ;

After this code you will have your image in the jpeg nsdata and the correspoding dictionary for that image in the mutable cfdictionary.

All you have to do now is:

    CGImageSourceRef source = CGImageSourceCreateWithData((__bridge CFDataRef)jpeg, NULL);

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

    NSMutableData *dest_data = [NSMutableData data];


    CGImageDestinationRef destination = CGImageDestinationCreateWithData((__bridge CFMutableDataRef)dest_data,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,source,0, (CFDictionaryRef) mutable);

    //tell the destination to write the image data and metadata into our data object.
    //It will return false if something goes wrong
    BOOL success = CGImageDestinationFinalize(destination);

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

    //now we have the data ready to go, so do whatever you want with it
    //here we just write it to disk at the same path we were passed

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
    NSString *documentsDirectory = [paths objectAtIndex:0]; // Get documents folder
    NSString *dataPath = [documentsDirectory stringByAppendingPathComponent:@"ImagesFolder"];

    NSError *error;
    if (![[NSFileManager defaultManager] fileExistsAtPath:dataPath])
        [[NSFileManager defaultManager] createDirectoryAtPath:dataPath withIntermediateDirectories:NO attributes:nil error:&error]; //Create folder

    //    NSString *imageName = @"ImageName";

    NSString *fullPath = [dataPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.jpg", name]]; //add our image to the path

    [dest_data writeToFile:fullPath atomically:YES];

    //cleanup

    CFRelease(destination);
    CFRelease(source);

Note how I'm not saving using the ALAssets but directly into a folder of my choice.

Btw most of this code can be found in the link I posted at first.

Thanks. But have you done any optimizations for memory? I'm getting memory warnings due to the duplication of the image data in your method. There's the jpeg nsdata, then a destination. I saw in your linked answer a way to not duplicate, but it was using sample buffers, which I'm not using for photos taken via UIImagePickerController. — akaru, Feb 17 '12 at 22:51
Do you mean you are using the default method to take pictures? the one that automatically saves to the camera roll? I thought that one saved the image with the metadata included. If not the apple example does. — Pochi, Feb 18 '12 at 16:41
I'm using the picker, but as a camera. In this case I get a UIImage directly, along with some metadata. I then have to inject gps data, etc. I still have to save it manually to another folder. — akaru, Feb 18 '12 at 18:12
I see what you mean, i havent tried any optimization methods but the only thing i can think of would be using the kCGImageSourceShouldCache set to False when you create the source = CGImageSourceCreateWithData((__bridge CFDataRef)jpeg, NULL); (Pass it instead of the null as a dictionary with that key set to false). However i do not know if it will work or not. — Pochi, Feb 21 '12 at 02:19
where are you getting your *data* variable in the following line?: 'NSMutableData *dest_data = [NSMutableData data];' Would be great to know. didn't get it working yet... — suMi, Nov 11 '13 at 17:08
that one is sort of a placeholder which is used later as the destination data. its like allocating the space for data. — Pochi, Nov 12 '13 at 00:07
@Chiquis this is working fine to me for local images , but when i upload image on google drive , it don't show anything. Can you help me? Thanks — Khalid Usman, Jan 22 '14 at 12:02

score 4 · Answer 3 · answered Feb 12 '15 at 08:48

There is easier way. If you need to save some exif, you can use SimpleExif pod

First create a ExifContainer:

ExifContainer *container = [[ExifContainer alloc] init];

and populate it with all requred data:

[container addUserComment:@"A long time ago, in a galaxy far, far away"];
[container addCreationDate:[NSDate dateWithTimeIntervalSinceNow:-10000000]];
[container addLocation:locations[0]];

Then you can add this data to image:

NSData *imageData = [[UIImage imageNamed:@"DemoImage"] addExif:container];

Then you just save this data as a JPEG

score 1 · Answer 4 · answered Nov 27 '17 at 23:18

I faced the same problem, now I can upload files with EXIF data, also you can compress photo if need it, this solved the issue for me:

// Get your image.
UIImage *loImgPhoto = [self getImageFromAsset:loPHAsset];

// Get your metadata (includes the EXIF data).
CGImageSourceRef loImageOriginalSource = CGImageSourceCreateWithData(( CFDataRef) loDataFotoOriginal, NULL);
NSDictionary *loDicMetadata = (__bridge NSDictionary *) CGImageSourceCopyPropertiesAtIndex(loImageOriginalSource, 0, NULL);

// Set your compression quality (0.0 to 1.0).
NSMutableDictionary *loDicMutableMetadata = [loDicMetadata mutableCopy];
[loDicMutableMetadata setObject:@(lfCompressionQualityValue) forKey:(__bridge NSString *)kCGImageDestinationLossyCompressionQuality];

// Create an image destination.
NSMutableData *loNewImageDataWithExif = [NSMutableData data];
CGImageDestinationRef loImgDestination = CGImageDestinationCreateWithData((__bridge CFMutableDataRef)loNewImageDataWithExif, CGImageSourceGetType(loImageOriginalSource), 1, NULL);


// Add your image to the destination.
CGImageDestinationAddImage(loImgDestination, loImgPhoto.CGImage, (__bridge CFDictionaryRef) loDicMutableMetadata);

// Finalize the destination.
if (CGImageDestinationFinalize(loImgDestination))
   {
       NSLog(@"Successful image creation.");                   
       // process the image rendering, adjustment data creation and finalize the asset edit.


       //Upload photo with EXIF metadata
       [self myUploadMethod:loNewImageDataWithExif];

    }
    else
    {
          NSLog(@"Error -> failed to finalize the image.");                         
    }

CFRelease(loImageOriginalSource);
CFRelease(loImgDestination);

getImageFromAsset method:

-(UIImage *)getImageFromAsset:(PHAsset *)aPHAsset

{
    __block  UIImage *limgImageResult;

    PHImageRequestOptions *lPHImageRequestOptions = [PHImageRequestOptions new];
    lPHImageRequestOptions.synchronous = YES;

    [self.imageManager requestImageForAsset:aPHAsset
                                 targetSize:PHImageManagerMaximumSize
                                contentMode:PHImageContentModeDefault//PHImageContentModeAspectFit
                                    options:lPHImageRequestOptions
                              resultHandler:^(UIImage *limgImage, NSDictionary *info) {

                                  limgImageResult = limgImage;
                              }];


    return limgImageResult;
}

score 0 · Answer 5 · answered Dec 08 '16 at 15:57

0

Here's the basics of setting Make and Model metadata on a .jpg file in Swift 3 https://gist.github.com/lacyrhoades/09d8a367125b6225df5038aec68ed9e7 The higher level versions, like using ExifContainer pod, did not work for me.

answered Dec 08 '16 at 15:57

snakeoil

497
4
12

did you wrap this in an extension or method, or just include the code in your save methods? – Maury Markowitz Mar 14 '17 at 20:34

How to write exif metadata to an image (not the camera roll, just a UIImage or JPEG)

5 Answers5

Linked