编辑视频时，应用程序始终崩溃

Question

我正在尝试创建一个新的应用程序，用于在iPhone上编辑视频，并使用AVFoundation框架。当使用AVMutableComposition和AVMutableVideoComposition生成视频时，应用程序因内存崩溃，有没有更好的方法来编辑视频？或者如何优化它？

以下是代码，我认为这主要是因为我创建的 animatedTitleLayer ，我添加了大约5张照片，以执行核心动画。

    // Set up Core Animation layers to contribute a title animation overlay if we have a title set.
    if (self.titleText) {
        animatedTitleLayer = [self buildAnimatedTitleLayerForSize:videoSize];

        if (! forPlayback) {
            // For export: build a Core Animation tree that contains both the animated title and the video.
            CALayer *parentLayer = [CALayer layer];
            CALayer *videoLayer = [CALayer layer];
            parentLayer.frame = CGRectMake(0, 0, videoSize.width, videoSize.height);
            videoLayer.frame = CGRectMake(0, 0, videoSize.width, videoSize.height);
            [parentLayer addSublayer:videoLayer];
            [parentLayer addSublayer:animatedTitleLayer];

            if (! videoComposition) {
                // No transition set -- make a "pass through video track" video composition so we can include the Core Animation tree as a post-processing stage.
                videoComposition = [AVMutableVideoComposition videoComposition];

                [self buildPassThroughVideoComposition:videoComposition forComposition:composition];
            }

            videoComposition.animationTool = [AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:videoLayer inLayer:parentLayer];
        }
    }

    if (videoComposition) {
        // Every videoComposition needs these properties to be set:
        videoComposition.frameDuration = CMTimeMake(1, 30); // 30 fps
        videoComposition.renderSize = videoSize;
    }

还有其他将核心动画转换为视频吗？在上面的代码中，我必须同时添加所有照片。

有一个应用程序，Splice video editor，非常好，快速和稳定。我将要做的几乎与它相同，将核心动画转换为视频，但速度慢且不稳定。