ios - 为什么 -writeImageToSavedPhotosAlbum 不正确地定位我的图片？

Question

我正在使用 -writeImageToSavedPhotosAlbum 将图像发送到照片库。我遇到的问题是，尽管指定了一个方向，但图像最终的方向是错误的。

事实上，似乎面向 AVCaptureVideoOrientationPortrait 的最终看起来像 AVCaptureVideoOrientationPortraitUpsideDown，和 AVCaptureVideoOrientationLandscapeLeft 最终看起来像 AVCaptureVideoOrientationLandscapeRight ，反之亦然。

发生这种情况有什么原因吗？以下是更多详细信息:

我没有 ViewController 为我的 View 自动更改方向。
所有图像显示 [image imageOrientation] 等于 AVCaptureVideoOrientationPortrait，但我跟踪实际方向并将其独立传递给 -writeImageToSavedPhotosAlbum。

我正在使用:-writeImageToSavedPhotosAlbum:orientation:completionBlock:

如果有人能阐明这一点，我将不胜感激。

更新:

尽管我在文档中看到了什么，

If you want to save a UIImage object, you can use the UIImage method CGImage to get a CGImageRef, and cast the image’s imageOrientation to ALAssetOrientation.

我继续更改传入的方向:

switch (lastOrientation) {
    case UIDeviceOrientationPortrait:
    default:
        alOrientation = ALAssetOrientationUp;
        break;
    case UIDeviceOrientationPortraitUpsideDown:
        alOrientation = ALAssetOrientationDown;
        break;
    case UIDeviceOrientationLandscapeLeft:
        alOrientation = ALAssetOrientationLeft;
        break;
    case UIDeviceOrientationLandscapeRight:
        alOrientation = ALAssetOrientationRight;
        break;

}
[library writeImageToSavedPhotosAlbum:[image CGImage]
                          orientation:(ALAssetOrientation) alOrientation// [image imageOrientation]
                      completionBlock:^(NSURL *assetURL, NSError *error) {
                            NSLog(@"completion block");
                      }];

现在，所有图像都以左边缘向下的方式进行定向，就好像它们是横向的一样。我仍然不正确，但至少我让它们统一定向。

另一个更新:

这行得通。为什么，我不知道:

switch (lockedOrientation) {
        case UIDeviceOrientationPortrait:
        default:
            alOrientation = ALAssetOrientationRight; //3 instead ofALAssetOrientationUp;
            break;
        case UIDeviceOrientationPortraitUpsideDown:
            alOrientation = ALAssetOrientationLeft; //2 insted of ALAssetOrientationDown;
            break;
        case UIDeviceOrientationLandscapeLeft:
            alOrientation = ALAssetOrientationUp; //0 instead of ALAssetOrientationLeft;
            break;
        case UIDeviceOrientationLandscapeRight:
            alOrientation = ALAssetOrientationDown; //1 instead of ALAssetOrientationRight;
            break;

    }
    [library writeImageToSavedPhotosAlbum:[image CGImage]
                              orientation:(ALAssetOrientation) alOrientation// [image imageOrientation]
                          completionBlock:^(NSURL *assetURL, NSError *error) {
                                NSLog(@"completion block");
                          }];

Answer 1

您遇到此问题是因为 UIDeviceOrientation 和 ALAssetOrientation 具有不同的枚举值。检查下面两个枚举的定义:

typedef NS_ENUM(NSInteger, UIDeviceOrientation) {
    UIDeviceOrientationUnknown,
    UIDeviceOrientationPortrait,            // Device oriented vertically, home button on the bottom
    UIDeviceOrientationPortraitUpsideDown,  // Device oriented vertically, home button on the top
    UIDeviceOrientationLandscapeLeft,       // Device oriented horizontally, home button on the right
    UIDeviceOrientationLandscapeRight,      // Device oriented horizontally, home button on the left
    UIDeviceOrientationFaceUp,              // Device oriented flat, face up
    UIDeviceOrientationFaceDown             // Device oriented flat, face down
};

typedef NS_ENUM(NSInteger, ALAssetOrientation) {
    ALAssetOrientationUp,            // default orientation
    ALAssetOrientationDown,          // 180 deg rotation
    ALAssetOrientationLeft,          // 90 deg CCW
    ALAssetOrientationRight,         // 90 deg CW
    ALAssetOrientationUpMirrored,    // as above but image mirrored along other axis. horizontal flip
    ALAssetOrientationDownMirrored,  // horizontal flip
    ALAssetOrientationLeftMirrored,  // vertical flip
    ALAssetOrientationRightMirrored, // vertical flip
};

所以对于 UIDeviceOrientationUnknown 相同的将是 UIDeviceOrientationUnknown (int value 0);因为 UIDeviceOrientationPortrait 将等于 ALAssetOrientationDown(int 值 1)等等