在不将图像加载到内存的情况下访问图像属性

Question

我正在尝试从 UIImagePickerController 中挑选的图像中获取 GPS 数据

我使用this site 作为参考。

选择图片后，CGImageSourceRef 始终为空。

这是我的 NSLog 的输出

信息：{ UIImagePickerControllerMediaType = "public.image"; UIImagePickerControllerOriginalImage = "尺寸 {2448, 3264} 方向 3 比例 1.000000"; UIImagePickerControllerReferenceURL = "assets-library://asset/asset.JPG?id=B01DF2C7-B954-41D8-B3FE-6096706DF3BB&ext=JPG"; }

imageFileURL: assets-library://asset/asset.JPG?id=B01DF2C7-B954-41D8-B3FE-6096706DF3BB&ext=JPG

ImageSource 为空

这是我的代码：

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {

    NSLog(@"Info: %@", info.description);


    [picker dismissViewControllerAnimated:YES completion:^{


        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

            NSURL *imageFileURL = (NSURL*) info[UIImagePickerControllerReferenceURL];

            NSLog(@"imageFileURL: %@", imageFileURL.description);

            CGImageSourceRef imageSource = CGImageSourceCreateWithURL((CFURLRef) imageFileURL, NULL);

            if (imageSource == NULL) {
                NSLog(@"ImageSource was Null");
                return;
            }

            NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
                                    [NSNumber numberWithBool:NO], (NSString *)kCGImageSourceShouldCache,
                                    nil];
            CFDictionaryRef imageProperties = CGImageSourceCopyPropertiesAtIndex(imageSource, 0, (CFDictionaryRef)options);
            CFRelease(imageSource);

            CFDictionaryRef gps = CFDictionaryGetValue(imageProperties, kCGImagePropertyGPSDictionary);
            if (gps) {
                NSString *latitudeString = (NSString *)CFDictionaryGetValue(gps, kCGImagePropertyGPSLatitude);
                NSString *latitudeRef = (NSString *)CFDictionaryGetValue(gps, kCGImagePropertyGPSLatitudeRef);
                NSString *longitudeString = (NSString *)CFDictionaryGetValue(gps, kCGImagePropertyGPSLongitude);
                NSString *longitudeRef = (NSString *)CFDictionaryGetValue(gps, kCGImagePropertyGPSLongitudeRef);
                NSLog(@"GPS Coordinates: %@ %@ / %@ %@", longitudeString, longitudeRef, latitudeString, latitudeRef);
            }

            dispatch_async(dispatch_get_main_queue(), ^{

            }); //distpach get main queue
        });//background queueu
    }];//picker completion

}

我不确定自己做错了什么。有什么帮助吗？

Answer 1

UIImagePickerControllerReferenceURL 已弃用。 You should use UIImagePickerControllerPHAsset instead. 假设 info 字典中有该键的 PHAsset，它还应该提供 location data as a CLLocation.

编辑：既然你说你需要支持早期的操作系统版本，那么这段代码对我来说是基于你已经拥有的。

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
  [picker dismissViewControllerAnimated:YES completion:^{
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

      NSURL *imageFileURL = info[UIImagePickerControllerImageURL];
      CGImageSourceRef imageSource = CGImageSourceCreateWithURL((__bridge CFURLRef)imageFileURL, NULL);

      if (imageSource == NULL) {
        NSLog(@"ImageSource was Null");
        return;
      }

      NSDictionary *options = @{(NSString *)kCGImageSourceShouldCache : @(NO)};
      CFDictionaryRef imageProperties = CGImageSourceCopyPropertiesAtIndex(imageSource, 0, (CFDictionaryRef)options);
      CFRelease(imageSource);

      CFDictionaryRef gps = CFDictionaryGetValue(imageProperties, kCGImagePropertyGPSDictionary);
      NSString *latitudeString = (NSString *)CFDictionaryGetValue(gps, kCGImagePropertyGPSLatitude);
      NSString *latitudeRef = (NSString *)CFDictionaryGetValue(gps, kCGImagePropertyGPSLatitudeRef);
      NSString *longitudeString = (NSString *)CFDictionaryGetValue(gps, kCGImagePropertyGPSLongitude);
      NSString *longitudeRef = (NSString *)CFDictionaryGetValue(gps, kCGImagePropertyGPSLongitudeRef);
      NSLog(@"GPS Coordinates: %@ %@ / %@ %@", longitudeString, longitudeRef, latitudeString, latitudeRef);
    });//background queue
  }];//picker completion
}