從iOS攝像頭捕捉視頻

Question

我需要通過攝像頭捕捉視頻。但它提供了以下錯誤：

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[AVCaptureDevice init:] - cannot instantiate a AVCaptureDevice directly.'

下面的代碼：

import UIKit 
import AVFoundation 

class ViewController: UIViewController, AVCaptureFileOutputRecordingDelegate { 

//ビデオのアウトプット 
private var myVideoOutPut:AVCaptureMovieFileOutput! 

//スタート&ストップボタン 
private var myButtonStart : UIButton! 
private var myButtonStop : UIButton! 

override func viewDidLoad() { 
    super.viewDidLoad() 

    //セッションの作成 
    let mySession : AVCaptureSession = AVCaptureSession() 

    //デバイス 
    var myDevice : AVCaptureDevice = AVCaptureDevice() 

    //出力先の設定 
    let myImageOutput : AVCaptureStillImageOutput = AVCaptureStillImageOutput() 


    //デバイス一覧の取得 
    let devices = AVCaptureDevice.devices() 

    //マイクを取得 
    //マイクをセッションのInputに追加 
    do{ 
     let audioCaptureDevice = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeAudio) 
     let audioInput = try AVCaptureDeviceInput(device: audioCaptureDevice) 
     if (mySession.canAddInput(audioInput)){ 
      mySession.addInput(audioInput) 
     } 
    }catch let error as NSError{ 
     print(error) 
    } 

    //バックライトをmyDeviceに格納 
    for device in devices { 
     if (device.position == AVCaptureDevicePosition.Back){ 
      myDevice = device as! AVCaptureDevice 
     } 
    } 

    //バックカメラを取得 
    do{ 
     let videoCaptureDevice = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo) 
     let videoInput = try AVCaptureDeviceInput(device: videoCaptureDevice) 
     //ビデオをセッションのInputに追加 
     if (mySession.canAddInput(videoInput)){ 
      mySession.addInput(videoInput) 
     } 
    }catch let error as NSError{ 
     print(error) 
    } 


    //セッションに出力先を追加 
    mySession.addOutput(myImageOutput) 

    //動畫の保存 
    myVideoOutPut = AVCaptureMovieFileOutput() 

    //ビデオ出力をOutputに追加 
    mySession.addOutput(myVideoOutPut) 

    //畫像を表示するレイヤーを生成 
    let myVideoLayer:AVCaptureVideoPreviewLayer = AVCaptureVideoPreviewLayer(session: mySession) 
    myVideoLayer.frame = self.view.bounds 
    myVideoLayer.videoGravity = AVLayerVideoGravityResizeAspectFill 

    //viewに追加 
    self.view.layer.addSublayer(myVideoLayer) 

    //セッション開始 
    mySession.startRunning() 

    // UIボタン作成 
    myButtonStart = UIButton(frame: CGRectMake(0,0,120,50)) 
    myButtonStop = UIButton(frame: CGRectMake(0,0,120,50)) 

    myButtonStart.backgroundColor = UIColor.redColor() 
    myButtonStop.backgroundColor = UIColor.grayColor() 

    myButtonStart.layer.masksToBounds = true 
    myButtonStop.layer.masksToBounds = true 

    myButtonStart.setTitle("撮影", forState: .Normal) 
    myButtonStop.setTitle("停止", forState: .Normal) 

    myButtonStart.layer.cornerRadius = 20 
    myButtonStop.layer.cornerRadius = 20 


    myButtonStart.layer.position = CGPoint(x: self.view.bounds.width/2 - 70, y: self.view.bounds.height-50) 
    myButtonStop.layer.position = CGPoint(x: self.view.bounds.width/2 - 70, y: self.view.bounds.height-50) 

    myButtonStart.addTarget(self, action: "onClickMyButton:", forControlEvents: .TouchUpInside) 
    myButtonStop.addTarget(self, action: "onClickMyButton:", forControlEvents: .TouchUpInside) 

    //UIボタンをViewに追加 
    self.view.addSubview(myButtonStart) 
    self.view.addSubview(myButtonStop) 
} 

//ボタンイベント 
internal func onClickMyButton(sender:UIButton){ 
    //撮影開始 
    if sender == myButtonStart { 
     let paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true) 

     //フォルダ 
     let documentsDirectory = paths[0] as! String 

     //ファイル名 
     let filePath:String? = "\(documentsDirectory)/test.mp4" 

     //URL 
     let fileURL:NSURL = NSURL(fileURLWithPath: filePath!) 

     //録畫開始 
     myVideoOutPut.startRecordingToOutputFileURL(fileURL, recordingDelegate: self) 

    } else if sender == myButtonStop { 
     myVideoOutPut.stopRecording() 

    } 
} 

//動畫がキャプチャーされた後に呼ばれるメソッド 
func captureOutput(captureOutput: AVCaptureFileOutput!, didFinishRecordingToOutputFileAtURL outputFileURL: NSURL!, fromConnections connections: [AnyObject]!, error: NSError!) { 
    print("didFinishRecordingToOutputFileAtURL") 
} 

//動畫のキャプチャーが開始された時に呼ばれるメソッド 
func captureOutput(captureOutput: AVCaptureFileOutput!, didStartRecordingToOutputFileAtURL fileURL: NSURL!, fromConnections connections: [AnyObject]!) { 
    print("didStartRecordingToOutputFileAtURL") 
} 

override func didReceiveMemoryWarning() { 
    super.didReceiveMemoryWarning() 
    // Dispose of any resources that can be recreated. 
} 


/* 
// MARK: - Navigation 

// In a storyboard-based application, you will often want to do a little preparation before navigation 
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) { 
// Get the new view controller using segue.destinationViewController. 
// Pass the selected object to the new view controller. 
} 
*/ 

}

Answer 1

你不能實例AVCaptureDevice。剛剛宣佈mydevice在作爲可選：

var myDevice : AVCaptureDevice? 

您已經在後面這行代碼分配給它一個參考：

myDevice = device as! AVCaptureDevice