Question

我一直在尝试使用UISaveVideoAtPathToSavedPhotosAlbum来保存我的视频（在应用程序中本地存储）。但是当我尝试保存它时，我收到一条错误消息“操作失败，因为视频文件无效且无法播放。”该文件只有大约一分钟的长度，是一个.mp4文件。我用MPMoviePlayer播放它没有问题，它只是不会保存。这是代码：

NSString *path = [[NSBundle mainBundle] pathForResource:@"videoFile" ofType:@"mp4"];
UISaveVideoAtPathToSavedPhotosAlbum(path, self, @selector(status:didFinishSavingWithError:contextInfo), nil);

这种方法不适用于iPad吗？它说“SavedPhotosAlbum”。这是否意味着我将不得不通过照片应用程序来查看它，或者只是方法的名称，它将在视频应用程序中？如果你能帮我解决这个问题，我将非常感激。

Answer 1

这是我的一个项目中的一些更简单的工作代码，如果它存在于下面的filePathString并且与设备的相册兼容，则应将电影/视频保存到相册。我猜测输入的文件路径中没有文件，或者（更有可能）电影尺寸和格式与iPad / iPhone的相册不兼容。 See the question about video formats compatible with iOS device photo albums for more details.

ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
// don't forget to link to the AssetsLibrary framework 
// and also #import <AssetsLibrary/AssetsLibrary.h>

NSString *filePathString = [[NSBundle mainBundle] pathForResource:@"videoFile" ofType:@"mp4"];
NSURL *filePathURL = [NSURL fileURLWithPath:filePathString isDirectory:NO];
if ([library videoAtPathIsCompatibleWithSavedPhotosAlbum:filePathURL]) {
    [library writeVideoAtPathToSavedPhotosAlbum:filePathURL completionBlock:^(NSURL *assetURL, NSError *error){
        if (error) {
            // TODO: error handling
        } else {
            // TODO: success handling
        }
    }];
}
[library release];

Answer 2

只要UIVideoAtPathIsCompatibleWithSavedPhotosAlbum（）返回true，它就应该有效。但是，我之前遇到过这个问题，似乎有更好的运气创建和ALAssetsLibrary对象，然后使用该方法：

- (void)writeVideoAtPathToSavedPhotosAlbum:(NSURL *)videoPathURL completionBlock:(ALAssetsLibraryWriteVideoCompletionBlock)completionBlock

我没有尝试将其编辑为通用或100％便携式。我刚刚抓住了为保存视频而编写的代码，为您提供了使用ALAssetLibrary的良好起点：

- (void) saveVideoFile:(NSString *)fullpathVideoFile completionTarget:(id)theCompletionTarget action:(SEL)theCompletionAction context:(id)theContext
    {
    writeFailed = NO;

    completionTarget = theCompletionTarget;
    completionAction = theCompletionAction;
    completionContext = theContext;

    //  ALAssetsLibraryWriteVideoCompletionBlock
    //
    void (^completionBlock)(NSURL *, NSError *) = ^(NSURL *assetURL, NSError *error)
        {
        if ( error != nil )
            {
            writeFailed = YES;
            }

        writingToLibrary = NO;

        [self notifyCompletionTarget];
        };


    // clean up from previous calls
    //  
    if ( assetURL != nil )
        {
        [assetURL release];
        assetURL = nil;
        }

    if ( assetFullPathName != nil )
        {
        [assetFullPathName release];
        assetFullPathName = nil;
        }

    writingToLibrary = YES;


    // make sure we have a good file
    //
    if ( [[NSFileManager defaultManager] fileExistsAtPath:fullpathVideoFile] == NO)
        {
        writingToLibrary = NO;
        writeFailed = YES;
        [self notifyCompletionTarget];
        return;
        }


    // set assetURL for sending to the library
    //
    assetFullPathName = [[NSMutableString alloc] initWithCapacity:(NSUInteger)1024];
    [assetFullPathName setString:fullpathVideoFile];

    assetURL = [[NSURL alloc] initFileURLWithPath:assetFullPathName isDirectory:NO];


    // Use possible alternative method if this method doesn't want to work
    //
    if ( [library videoAtPathIsCompatibleWithSavedPhotosAlbum:assetURL]==NO )
        {
        if ( UIVideoAtPathIsCompatibleWithSavedPhotosAlbum( assetFullPathName ) )
            {
            UISaveVideoAtPathToSavedPhotosAlbum( assetFullPathName, self, @selector(video:didFinishSavingWithError:contextInfo:), nil );
            }
        else
            {
            writingToLibrary = NO;
            writeFailed = YES;
            [self notifyCompletionTarget];
            }

        return;
        }


    // Write the video to the library
    //
    [library writeVideoAtPathToSavedPhotosAlbum:assetURL completionBlock:completionBlock];
    }

将视频保存到iPad视频应用

2 个答案: