iphone - 从 ALAssset 检索时的 CGImage 方向问题

Question

我刚刚开始学习 iPhone 应用程序开发。我正在尝试使用 ALAsset 类从我的相册中检索照片并将照片上传到我的服务器。然而，在人像模式下拍摄的照片向左旋转90度，而风景照片则正确上传。我究竟做错了什么？在 NSLog 中，我确实看到方向为 3，但照片仍然向左旋转 90 度。任何帮助将不胜感激。

这是我的代码片段:

ALAssetsLibraryAssetForURLResultBlock resultblock = ^(ALAsset *myasset)
{
   NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
   NSString *documentsDirectory = [paths objectAtIndex:0];

   imagePath = [[documentsDirectory stringByAppendingPathComponent:@"latest_photo.jpg"] copy];
   NSLog(@"imagePath = %@", imagePath);

   ALAssetRepresentation *rep = [myasset defaultRepresentation];
   ALAssetOrientation orientation = [rep orientation];
   NSLog(@"Orientation = %d", orientation);

   CGImageRef iref = [rep fullResolutionImage];

   if (iref) {
      UIImage *largeimage = [UIImage imageWithCGImage:iref scale:1.0 orientation:orientation];
      NSData *webData = UIImageJPEGRepresentation(largeimage,0.5);

      [webData writeToFile:imagePath atomically:YES];

      // Upload the image

Answer 1

对于代码的 Assets 导向部分，而不是

ALAssetRepresentation *rep = [myasset defaultRepresentation];
ALAssetOrientation orientation = [rep orientation];

尝试

ALAssetOrientation orientation = [[asset valueForProperty:@"ALAssetPropertyOrientation"] intValue];