使用 ImageIO 从图像中获取 EXIF 数据

Question

在我的应用程序中，我想从 ImagePickerController 读取图像元数据。 我这样尝试：

NSURL* imgURL = (NSURL *)[info valueForKey:UIImagePickerControllerReferenceURL];
NSLog(@"%@", imgURL);

CGImageSourceRef mySourceRef = CGImageSourceCreateWithURL((__bridge CFURLRef)imgURL, NULL);
NSDictionary *myMetadata = (__bridge NSDictionary *) CGImageSourceCopyPropertiesAtIndex(mySourceRef,0,NULL);

NSDictionary *exifDic = [myMetadata objectForKey:(NSString *)kCGImagePropertyExifDictionary];
NSDictionary *tiffDic = [myMetadata objectForKey:(NSString *)kCGImagePropertyTIFFDictionary];

NSLog(@"exifDic properties: %@", myMetadata); //all data
float rawShutterSpeed = [[exifDic objectForKey:(NSString *)kCGImagePropertyExifExposureTime] floatValue];
int decShutterSpeed = (1 / rawShutterSpeed);
NSLog(@"Camera %@",[tiffDic objectForKey:(NSString *)kCGImagePropertyTIFFModel]);
NSLog(@"Focal Length %@mm",[exifDic objectForKey:(NSString *)kCGImagePropertyExifFocalLength]);
NSLog(@"Shutter Speed %@", [NSString stringWithFormat:@"1/%d", decShutterSpeed]);
NSLog(@"Aperture f/%@",[exifDic objectForKey:(NSString *)kCGImagePropertyExifFNumber]);
NSNumber *ExifISOSpeed  = [[exifDic objectForKey:(NSString*)kCGImagePropertyExifISOSpeedRatings] objectAtIndex:0];
NSLog(@"ISO %i",[ExifISOSpeed integerValue]);
NSLog(@"Taken %@",[exifDic objectForKey:(NSString*)kCGImagePropertyExifDateTimeDigitized]);

但我收到 ImageIO 错误：

ImageIO：CGImageSourceCreateWithURL CFURLCreateDataAndPropertiesFromResource 失败，错误代码 -11。

我没有找到有关错误代码-11的文档，只找到有关-15（错误参数）的文档。 我希望你能有一个解决方案。

问候 s4l鱼