StackOverflow2013

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copied!<p>Scott, a developer at Apple, returned with my incident report and fixed the issue:</p> <blockquote> <p>The previous code above is writing <strong>string values</strong> for the GPS values - <em>this won't work</em>, they <strong>must be NS/CFNumbers</strong> (we extract a float value for EXIF).</p> </blockquote> <p>I'll be filing a bug report to Apple against their documentation.</p> <p>Although it took a week to get this response, I really do appreciate the support Apple provides to their developers. (thanks Scott!) <strong>;-)</strong></p> <p>Below is the improved code and its correct output:</p> <pre><code>[[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); //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:[NSNumber numberWithFloat:37.795] forKey:(NSString*)kCGImagePropertyGPSLatitude]; [GPSDictionary setObject:@"N" forKey:(NSString*)kCGImagePropertyGPSLatitudeRef]; [GPSDictionary setObject:[NSNumber numberWithFloat:122.410] forKey:(NSString*)kCGImagePropertyGPSLongitude]; [GPSDictionary setObject:@"W" forKey:(NSString*)kCGImagePropertyGPSLongitudeRef]; [GPSDictionary setObject:@"2012:10:18" forKey:(NSString*)kCGImagePropertyGPSDateStamp]; [GPSDictionary setObject:[NSNumber numberWithFloat:300] forKey:(NSString*)kCGImagePropertyGPSImgDirection]; [GPSDictionary setObject:[NSNumber numberWithFloat:37.795] forKey:(NSString*)kCGImagePropertyGPSDestLatitude]; [GPSDictionary setObject:@"N" forKey:(NSString*)kCGImagePropertyGPSDestLatitudeRef]; [GPSDictionary setObject:[NSNumber numberWithFloat:122.410] forKey:(NSString*)kCGImagePropertyGPSDestLongitude]; [GPSDictionary setObject:@"W" forKey:(NSString*)kCGImagePropertyGPSDestLongitudeRef]; [EXIFDictionary setObject:@"[S.D.] kCGImagePropertyExifUserComment" forKey:(NSString *)kCGImagePropertyExifUserComment]; [EXIFDictionary setObject:[NSNumber numberWithFloat:69.999] 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]; 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(@"Final properties %@", propDict); }]; </code></pre> <p>Which outputs this:</p> <pre><code>Final properties info { ColorModel = RGB; DPIHeight = 72; DPIWidth = 72; Depth = 8; Orientation = 6; PixelHeight = 2448; PixelWidth = 3264; "{Exif}" = { ApertureValue = "2.526069"; BrightnessValue = "0.547474"; ColorSpace = 1; ComponentsConfiguration = ( 0, 0, 0, 1 ); ExifVersion = ( 2, 2, 1 ); ExposureMode = 0; ExposureProgram = 2; ExposureTime = "0.05"; FNumber = "2.4"; Flash = 16; FlashPixVersion = ( 1, 0 ); FocalLenIn35mmFilm = 35; FocalLength = "4.28"; ISOSpeedRatings = ( 320 ); MeteringMode = 5; PixelXDimension = 3264; PixelYDimension = 2448; SceneCaptureType = 0; SensingMethod = 2; ShutterSpeedValue = "4.321929"; SubjectArea = ( 1631, 1223, 881, 881 ); SubjectDistance = "69.999"; UserComment = "[S.D.] kCGImagePropertyExifUserComment"; WhiteBalance = 0; }; "{GPS}" = { DateStamp = "2012:10:18"; DestLatitude = "37.795"; DestLatitudeRef = N; DestLongitude = "122.41"; DestLongitudeRef = W; ImgDirection = 300; Latitude = "37.795"; LatitudeRef = N; Longitude = "122.41"; LongitudeRef = W; }; "{JFIF}" = { DensityUnit = 1; JFIFVersion = ( 1, 1 ); XDensity = 72; YDensity = 72; }; "{TIFF}" = { Orientation = 6; ResolutionUnit = 2; XResolution = 72; YResolution = 72; "_YCbCrPositioning" = 1; }; } </code></pre> <p>As you can see, all values are now properly embedded into the EXIF header and I've tested that this is correctly written with the JPG to the camera roll.</p> <p>Enjoy! :)</p>

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