需要使用iPhone SDK的AVMutableVideoComposition的提示

Question

AVFoundation框架提供了AVMutableVideoComposition類（AVVideoComposition的可變變體）。它看起來像你可以直接渲染CoreAnimations到這個類的一個實例來創建一個視頻，但我不知道如何將組合保存到一個文件或如何使用它，真的。從UIViewController調用的以下代碼似乎可以用來創建合成和動畫，但是，那麼，我很難理解如何使用合成。任何幫助或指導，非常感謝。

static AVMutableVideoComposition *videoComposition = nil; 
- (void)animationDidStop:(CAAnimation *)animation finished:(BOOL)flag { 
//Do something with videoComposition here... how to save it to a file? 
NSLog(@"videoComposition: %@", videoComposition); 
[videoComposition release]; videoComposition = nil; 
} 

- (IBAction)createVideoComposition:(id)sender { 
AVVideoCompositionCoreAnimationTool *videoCompositionCoreAnimationTool = [AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:self.view.layer inLayer:self.view.layer]; 
videoComposition = [[AVMutableVideoComposition videoComposition] retain]; 
[videoComposition setRenderSize:CGSizeMake(320.0, 480.0)]; 
[videoComposition setRenderScale:1.0]; 
[videoComposition setFrameDuration:CMTimeMake(1, 10)]; 
[videoComposition setAnimationTool:videoCompositionCoreAnimationTool]; 
//add a basic animation to shake the controller's view 
CAKeyframeAnimation *shakeAnimation = [CAKeyframeAnimation animationWithKeyPath:@"position"]; 
shakeAnimation.delegate = self; 
shakeAnimation.removedOnCompletion = YES; 
shakeAnimation.duration = 0.5; 
CGMutablePathRef path = CGPathCreateMutable(); 
CGFloat midX = self.view.center.x; 
CGFloat midY = self.view.center.y; 
CGPathMoveToPoint(path, nil, midX, midY); 
CGPathAddLineToPoint(path, nil, midX + 10.0, midY); 
CGPathAddLineToPoint(path, nil, midX - 20.0, midY); 
CGPathAddLineToPoint(path, nil, midX + 15.0, midY); 
CGPathAddLineToPoint(path, nil, midX - 5.0, midY); 
CGPathAddLineToPoint(path, nil, midX, midY); 
shakeAnimation.path = path; 
CFRelease(path); 
[self.view.layer addAnimation:shakeAnimation forKey:@"shakeAnimation"]; 
} 

感謝， 喬恩

Answer 1

不知道是否有幫助。

AVAssetExportSession *session = [[AVAssetExportSession alloc] initWithAsset:composition presetName:AVAssetExportPresetHighestQuality]; 
    session.videoComposition = videoComposition; 
    session.outputURL = outputURL; 
    session.outputFileType = AVFileTypeQuickTimeMovie; 
    [session exportAsynchronouslyWithCompletionHandler: 
     ^(void) 
{ 
     NSLog(@"TADA!") 
    }];