ios - 无法弄清楚为什么 VideoDeviceInput 没有被添加到我的 AVCaptureSession

Question

一切正常。输出已正确添加，一切都已正确初始化，相机弹出等。唯一不起作用的是将视频设备作为输入添加到捕获 session 或此相机中，我无法理解为什么会发生这种情况。

也许不同的眼睛可以捕捉到这里发生的事情。如果有人可以看一下，我将不胜感激？

import UIKit
import Foundation
import AVFoundation


class CameraViewController: UIViewController {

    @IBOutlet var recordingImage: UIImageView!
    @IBOutlet var captureButton: UIButton!
    @IBOutlet var flipCameraButton: UIButton!
    @IBOutlet var switchCaptureButton: UIButton!
    @IBOutlet weak var cameraView: UIView!

    let cameraCapturePosition: AVCaptureDevicePosition = AVCaptureDevicePosition.Back
    let session: AVCaptureSession = AVCaptureSession()
    let totalTime: Float64 = 1800               // total time in seconds
    let preferredTimeScale: Int32 = 45          // 45 FPS
    let minFreeSpace: Int64 = 65999999         // minimum free disk space

    var dataObject: AnyObject?
    var cameraCaptureDevice: AVCaptureDevice?
    var audioCaptureDevice: AVCaptureDevice?
    var movieFileOutput: AVCaptureMovieFileOutput?
    var stillImageOutput: AVCaptureStillImageOutput?
    var videoPreviewLayer: AVCaptureVideoPreviewLayer?
    var captureConnection: AVCaptureConnection?
    var weAreRecording: Bool = false
    var beenHereBefore: Bool = false
    var devicesSet: Bool = false

    //**************** VIEW DID LOAD *****************
    override func viewDidLoad() {

        super.viewDidLoad()

        registerRuntimeError()
        registerDeviceConnections()
        setSessionPreset()
    }

    //**************** VIEW DID APPEAR *****************
    override func viewDidAppear(animated: Bool) {

        //------INITIALIZE THE CAMERA------
        if (!self.beenHereBefore) {
            addInputs()
            addOutputs()
            setCameraOutputProperties()
            startSession()
            self.beenHereBefore = true
        }
        else {
            println("Been Here Before")
        }

        self.weAreRecording = false
    }

    //**************** DID RECEIVE MEMORY WARNING *****************
    override func didReceiveMemoryWarning() {

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

    //**************** TAKES A PHOTO OR VIDEO *****************
    @IBAction func didPressCapture(sender: AnyObject) {


    }

    //**************** SWITCHES THE CAPTURE MODES OF THE CAMERA ****************
    @IBAction func didPressSwitchCapture(sender: AnyObject) {
//        
//        ----------- TODO ------------
//        
    }

    //**************** FLIPS THE CAMERA BACK AND FORTH ****************
    @IBAction func didPressFlipCamera(sender: AnyObject) {
//        
//        ----------- TODO ------------
//        
    }


    //**************** INITIALIZE THE VIDEO CAPTURE SESSION ****************
    func setSessionPreset() {

        println("initializing video capture session")

        //----- SET THE IMAGE QUALITY / RESOLUTION -----
        //Options:
        //  AVCaptureSessionPresetHigh - Highest recording quality (varies per device)
        //  AVCaptureSessionPresetMedium - Suitable for WiFi sharing (actual values may change)
        //  AVCaptureSessionPresetLow - Suitable for 3G sharing (actual values may change)
        //  AVCaptureSessionPreset640x480 - 640x480 VGA (check its supported before setting it)
        //  AVCaptureSessionPreset1280x720 - 1280x720 720p HD (check its supported before setting it)
        //  AVCaptureSessionPresetPhoto - Full photo resolution (not supported for video output)
        if session.canSetSessionPreset(AVCaptureSessionPresetHigh) {
            println("Capture Session preset is set to High Quality")
            session.sessionPreset = AVCaptureSessionPresetHigh
        }
        else {
            //------IF FAILED, SET DEFAULT PRESET TO MEDIUM------
            println("Capture Session preset is set to Medium Quality")
            session.sessionPreset = AVCaptureSessionPresetMedium
        }
    }

    //**************** ADD CAPTURE SESSION INPUTS ****************
    func addInputs() {

        println("Getting array of available capture devices")

        //------GRAB ALL OF THE DEVICES------
        let devices = AVCaptureDevice.devices()

        //------FIND THE CAMERA MATCHING THE POSITION------
        for device in devices {
            if device.position == self.cameraCapturePosition {
                self.cameraCaptureDevice = device as? AVCaptureDevice
                println("Back camera has been added")
            }
        }

        var error1: NSError? = nil
        let videoDeviceInput = AVCaptureDeviceInput(device: self.cameraCaptureDevice, error: &error1)

        //------PRINT ERROR IF ONE OCCURS------
        if error1 != nil {
            println("Error1 ---: \(error1?.description)")
        }

        //------ADD VIDEO AND AUDIO INPUT------
        println("Trying to add video input")
        if self.cameraCaptureDevice != nil {
            if self.session.canAddInput(videoDeviceInput) {
                self.session.addInput(videoDeviceInput)
                println("Successfully added video input")
                self.devicesSet = true
            }
            else {
                // !!!!!!!!------- VIDEO INPUT IS NOT BEING ADDED TO THE SESSION -----------!!!!!!!!!!!
                println("Could not add video input")
            }
        }
        else {
            println("Could not create video device")
        }
    }

    //**************** ADD CAPTURE SESSION OUTPUTS ****************
    func addOutputs() {

        //------SET JPEG OUTPUT------
        println("Setting JPEG Output")
        self.stillImageOutput = AVCaptureStillImageOutput()
        let outputSettings = [ AVVideoCodecKey : AVVideoCodecJPEG ]
        self.stillImageOutput!.outputSettings = outputSettings
        println("Successfully configured JPEG Ouput")

        //------SET MOVIE FILE OUPUT MAX DURATION------
        println("Setting Movie File Max Duration")
        self.movieFileOutput = AVCaptureMovieFileOutput()
        let maxDuration:CMTime = CMTimeMakeWithSeconds(self.totalTime, self.preferredTimeScale)
        self.movieFileOutput!.maxRecordedDuration = maxDuration
        println("Successully set movie file max duration")
        println("Setting movie file minimun byte space")
        self.movieFileOutput!.minFreeDiskSpaceLimit = self.minFreeSpace
        println("Successfully added minium free space")


        //------ADD JPEG OUTPUT AND MOVIE FILE OUTPUT TO SESSION OUTPUT------
        println("Adding still image and movie file output")
        if self.session.canAddOutput(self.stillImageOutput) && self.session.canAddOutput(self.movieFileOutput) {
            self.session.addOutput(self.stillImageOutput)
            self.session.addOutput(self.movieFileOutput)
            println("Successfully added still image and movie file outputs")
        }
        else {
            println("Could Not Add still image and movie file output")
        }
    }

    //***************** SET ANY CAMERA PROPERTIES HERE ****************
    func setCameraOutputProperties () {

        //------INIT CAPTURE CONNECTION------
        println("initializing the capture connection")
        self.captureConnection = self.movieFileOutput!.connectionWithMediaType(AVMediaTypeVideo)
        println("Capture Connection succesfully initialized")
    }

    //***************** REGISTER FOR RUNTIME NOTIFICATIONS ****************
    func registerRuntimeError() {

        println("Registering for runtime errors")
        NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("didHaveRuntimeError"), name: AVCaptureSessionRuntimeErrorNotification, object: self.session)
    }

    //**************** REGISTER FOR DEVICE CONNECTION NOTIFICATIONS *****************
    func registerDeviceConnections() {

        println("Registering for connection notifications")
        NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("deviceConnected"), name: AVCaptureDeviceWasConnectedNotification, object: self.session)
        NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("deviceDisconnected"), name: AVCaptureDeviceWasDisconnectedNotification, object: self.session)
    }

    //**************** START THE CAPTURE SESSION ****************
    func startSession() {

        println("About to add session inputs...")
        addInputs()
        println("Start configuring the capture")

        //------CONFIG CAPTURE SESSION------
        if !session.running {

            println("Displaying camera in UI")

            //------DISPLAY CAMERA IN UI------
            self.videoPreviewLayer = AVCaptureVideoPreviewLayer(session: self.session)
            println("Video Preview Layer set")
            self.cameraView.layer.addSublayer(self.videoPreviewLayer)
            println("Video Preview Layer Added as sublayer")
            self.videoPreviewLayer!.frame = self.cameraView.layer.frame
            println("Video Preview frame set")
            self.videoPreviewLayer!.videoGravity = AVLayerVideoGravityResizeAspectFill
            println("Camera successully can display")

            //------START CAMERA------
            self.session.startRunning()
            println("Capture Session initiated")
        }
        else {
            println("Session is already running, no need to start it again")
        }
    }


    /*
    // 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

我觉得你错过了

AVCaptureFileOutputRecordingDelegate

你的错误打印出来了吗？ :

println("Could not add video input")

println("Could not create video device")