iOS基于AVFoundation 制作用于剪辑视频项目

 //选择视频
       @objc func selectVideo() {
           if UIImagePickerController.isSourceTypeAvailable(.photoLibrary) {
               //初始化图片控制器
               let imagePicker = UIImagePickerController()
               //设置代理
               imagePicker.delegate = self
               //指定图片控制器类型
               imagePicker.sourceType = .photoLibrary
               //只显示视频类型的文件
               imagePicker.mediaTypes = [kUTTypeMovie as String]
               //弹出控制器，显示界面
               self.present(imagePicker, animated: true, completion: nil)
           }
           else {
               print("读取相册错误")
           }
       }

    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
        //获取视频路径（选择后视频会自动复制到app临时文件夹下）
        guard let videoURL = info[UIImagePickerController.InfoKey.mediaURL] as? URL else {
            return
        }
        let pathString = videoURL.relativePath
        print("视频地址：\(pathString)")

        //图片控制器退出
        self.dismiss(animated: true, completion: {
            let editorVC = EditorVideoViewController.init(with: videoURL)

            editorVC.modalPresentationStyle = UIModalPresentationStyle.fullScreen
            self.present(editorVC, animated: true) {

            }
        })
    }

 /**
    	@method			generateCGImagesAsynchronouslyForTimes:completionHandler:
    	@abstract		Returns a series of CGImageRefs for an asset at or near the specified times.
    	@param			requestedTimes
    					An NSArray of NSValues, each containing a CMTime, specifying the asset times at which an image is requested.
    	@param			handler
    					A block that will be called when an image request is complete.
    	@discussion		Employs an efficient "batch mode" for getting images in time order.
    					The client will receive exactly one handler callback for each requested time in requestedTimes.
    					Changes to generator properties (snap behavior, maximum size, etc...) will not affect outstanding asynchronous image generation requests.
    					The generated image is not retained.  Clients should retain the image if they wish it to persist after the completion handler returns.
    */
    open func generateCGImagesAsynchronously(forTimes requestedTimes: [NSValue], completionHandler handler: @escaping AVAssetImageGeneratorCompletionHandler)

func splitVideoFileUrlFps(splitFileUrl:URL, fps:Float, splitCompleteClosure:@escaping (Bool, [UIImage]) -> Void) {
        var splitImages = [UIImage]()
		
		//初始化 Asset
        let optDict = NSDictionary(object: NSNumber(value: false), forKey: AVURLAssetPreferPreciseDurationAndTimingKey as NSCopying)
        let urlAsset = AVURLAsset(url: splitFileUrl, options: optDict as? [String : Any])

        let cmTime = urlAsset.duration
        let durationSeconds: Float64 = CMTimeGetSeconds(cmTime)

        var times = [NSValue]()
        let totalFrames: Float64 = durationSeconds * Float64(fps)
        var timeFrame: CMTime

		//定义 CMTime 即请求缩略图的时间间隔
        for i in 0...Int(totalFrames) {
            timeFrame = CMTimeMake(value: Int64(i), timescale: Int32(fps))
            let timeValue = NSValue(time: timeFrame)

            times.append(timeValue)
        }

        let imageGenerator = AVAssetImageGenerator(asset: urlAsset)
        imageGenerator.requestedTimeToleranceBefore = CMTime.zero
        imageGenerator.requestedTimeToleranceAfter = CMTime.zero

        let timesCount = times.count
		
		//调用获取缩略图的方法
        imageGenerator.generateCGImagesAsynchronously(forTimes: times) { (requestedTime, image, actualTime, result, error) in

        var isSuccess = false
        switch (result) {
        case AVAssetImageGenerator.Result.cancelled:
            print("cancelled------")

        case AVAssetImageGenerator.Result.failed:
            print("failed++++++")

        case AVAssetImageGenerator.Result.succeeded:

            let framImg = UIImage(cgImage: image!)

            splitImages.append(self.flipImage(image: framImg, orientaion: 1))
            if (Int(requestedTime.value) == (timesCount-1)) { //最后一帧时 回调赋值
                isSuccess = true
                splitCompleteClosure(isSuccess, splitImages)
                print("completed")
            }
        }
        }
    }

				//调用时利用回调更新 UI
self.splitVideoFileUrlFps(splitFileUrl: url, fps: 1) { [weak self](isSuccess, splitImgs) in
            if isSuccess {
                //由于方法是异步的，所以需要回主线程更新 UI
                DispatchQueue.main.async {
                
                    }
                print("图片总数目imgcount:\(String(describing: self?.imageArr.count))")
            }
        }

 /**
     @method			seekToTime:toleranceBefore:toleranceAfter:
     @abstract			Moves the playback cursor within a specified time bound.
     @param				time
     @param				toleranceBefore
     @param				toleranceAfter
     @discussion		Use this method to seek to a specified time for the current player item.
    					The time seeked to will be within the range [time-toleranceBefore, time+toleranceAfter] and may differ from the specified time for efficiency.
    					Pass kCMTimeZero for both toleranceBefore and toleranceAfter to request sample accurate seeking which may incur additional decoding delay. 
    					Messaging this method with beforeTolerance:kCMTimePositiveInfinity and afterTolerance:kCMTimePositiveInfinity is the same as messaging seekToTime: directly.
     */
    open func seek(to time: CMTime, toleranceBefore: CMTime, toleranceAfter: CMTime)

	let totalTime = self.avPlayer.currentItem?.duration
	let scale = self.avPlayer.currentItem?.duration.timescale
	
	//width：跳转到的视频轨长度 videoWidth：视频轨总长度
 	let process = width / videoWidth
 	
      //快进函数
 	self.avPlayer.seek(to: CMTimeMake(value: Int64(totalTime * process * scale!), timescale: scale!), toleranceBefore: CMTime.zero, toleranceAfter: CMTime.zero)

/**
    	@method			addPeriodicTimeObserverForInterval:queue:usingBlock:
    	@abstract		Requests invocation of a block during playback to report changing time.
    	@param			interval
    	  The interval of invocation of the block during normal playback, according to progress of the current time of the player.
    	@param			queue
    	  The serial queue onto which block should be enqueued.  If you pass NULL, the main queue (obtained using dispatch_get_main_queue()) will be used.  Passing a
    	  concurrent queue to this method will result in undefined behavior.
    	@param			block
    	  The block to be invoked periodically.
    	@result
    	  An object conforming to the NSObject protocol.  You must retain this returned value as long as you want the time observer to be invoked by the player.
    	  Pass this object to -removeTimeObserver: to cancel time observation.
    	@discussion		The block is invoked periodically at the interval specified, interpreted according to the timeline of the current item.
    					The block is also invoked whenever time jumps and whenever playback starts or stops.
    					If the interval corresponds to a very short interval in real time, the player may invoke the block less frequently
    					than requested. Even so, the player will invoke the block sufficiently often for the client to update indications
    					of the current time appropriately in its end-user interface.
    					Each call to -addPeriodicTimeObserverForInterval:queue:usingBlock: should be paired with a corresponding call to -removeTimeObserver:.
    					Releasing the observer object without a call to -removeTimeObserver: will result in undefined behavior.
    */
    open func addPeriodicTimeObserver(forInterval interval: CMTime, queue: DispatchQueue?, using block: @escaping (CMTime) -> Void) -> Any

//player的监听
        self.avPlayer.addPeriodicTimeObserver(forInterval: CMTimeMake(value: 1, timescale: 120), queue: DispatchQueue.main) { [weak self](time) in
                //与轨道的联动操作
        }

 /**
        @method         insertTimeRange:ofTrack:atTime:error:
        @abstract       Inserts a timeRange of a source track into a track of a composition.
        @param          timeRange
                        Specifies the timeRange of the track to be inserted.
        @param          track
                        Specifies the source track to be inserted. Only AVAssetTracks of AVURLAssets and AVCompositions are supported (AVCompositions starting in MacOS X 10.10 and iOS 8.0).
        @param          startTime
                        Specifies the time at which the inserted track is to be presented by the composition track. You may pass kCMTimeInvalid for startTime to indicate that the timeRange should be appended to the end of the track.
        @param          error
                        Describes failures that may be reported to the user, e.g. the asset that was selected for insertion in the composition is restricted by copy-protection.
        @result         A BOOL value indicating the success of the insertion.
        @discussion
          You provide a reference to an AVAssetTrack and the timeRange within it that you want to insert. You specify the start time in the target composition track at which the timeRange should be inserted.
    
          Note that the inserted track timeRange will be presented at its natural duration and rate. It can be scaled to a different duration (and presented at a different rate) via -scaleTimeRange:toDuration:.
    */
    open func insertTimeRange(_ timeRange: CMTimeRange, of track: AVAssetTrack, at startTime: CMTime) throws

	let composition = AVMutableComposition()
            //合并视频、音频轨道
    let videoTrack = composition.addMutableTrack(
                        withMediaType: AVMediaType.video, preferredTrackID: CMPersistentTrackID())
  	let audioTrack = composition.addMutableTrack(
                        withMediaType: AVMediaType.audio, preferredTrackID: CMPersistentTrackID())


 	let asset = AVAsset.init(url: self.url)

	var insertTime: CMTime = CMTime.zero

 	let timeScale = self.avPlayer.currentItem?.duration.timescale

			//循环每个片段的信息
	for clipsInfo in self.clipsInfoArr {
            
            //片段的总时间
		let clipsDuration = Double(Float(clipsInfo.width) / self.videoWidth) * self.totalTime
            
            //片段的开始时间
		let startDuration = -Float(clipsInfo.offset) / self.perSecondLength

      	do {
           	try videoTrack?.insertTimeRange(CMTimeRangeMake(start: CMTimeMake(value: Int64(startDuration * Float(timeScale!)), timescale: timeScale!), duration:CMTimeMake(value: Int64(clipsDuration * Double(timeScale!)), timescale: timeScale!)), of: asset.tracks(withMediaType: AVMediaType.video)[0], at: insertTime)
                } catch _ {}

		do {
         	try audioTrack?.insertTimeRange(CMTimeRangeMake(start: CMTimeMake(value: Int64(startDuration * Float(timeScale!)), timescale: timeScale!), duration:CMTimeMake(value: Int64(clipsDuration * Double(timeScale!)), timescale: timeScale!)), of: asset.tracks(withMediaType: AVMediaType.audio)[0], at: insertTime)
      		 } catch _ {}
   		insertTime = CMTimeAdd(insertTime, CMTimeMake(value: Int64(clipsDuration * Double(timeScale!)), timescale: timeScale!))
            }

  		videoTrack?.preferredTransform = CGAffineTransform(rotationAngle: CGFloat.pi / 2)

            //获取合并后的视频路径
  		let documentsPath = NSSearchPathForDirectoriesInDomains(.documentDirectory,.userDomainMask,true)[0]

  		let destinationPath = documentsPath + "/mergeVideo-\(arc4random()%1000).mov"
     	print("合并后的视频：\(destinationPath)")