Swift 2調用viewdidload中的額外參數錯誤

我正在用Xcode 7更新我的應用到Swift 2。這是我的ViewController viewDidLoad的代碼。Swift 2調用viewdidload中的額外參數錯誤

override func viewDidLoad() { 
     super.viewDidLoad() 

    // Get an instance of the AVCaptureDevice class to initialize a device object and provide the video 
    // as the media type parameter. 
    let captureDevice = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo) 

    // Get an instance of the AVCaptureDeviceInput class using the previous device object. 
    var error:NSError? 

    let input: AnyObject! = AVCaptureDeviceInput.deviceInputWithDevice(captureDevice, error: &error) 

    if (error != nil) { 
     // If any error occurs, simply log the description of it and don't continue any more. 
     print("\(error?.localizedDescription)") 
     return 
    } 

    // Initialize the captureSession object. 
    captureSession = AVCaptureSession() 
    // Set the input device on the capture session. 
    captureSession?.addInput(input as! AVCaptureInput) 

    // Initialize a AVCaptureMetadataOutput object and set it as the output device to the capture session. 
    let captureMetadataOutput = AVCaptureMetadataOutput() 
    captureSession?.addOutput(captureMetadataOutput) 

    // Set delegate and use the default dispatch queue to execute the call back 
    captureMetadataOutput.setMetadataObjectsDelegate(self, queue: dispatch_get_main_queue()) 
    captureMetadataOutput.metadataObjectTypes = supportedBarCodes 

    // Initialize the video preview layer and add it as a sublayer to the viewPreview view's layer. 
    videoPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession) 
    videoPreviewLayer?.videoGravity = AVLayerVideoGravityResizeAspectFill 
    videoPreviewLayer?.frame = view.layer.bounds 
    view.layer.addSublayer(videoPreviewLayer!) 

    // Start video capture. 
    captureSession?.startRunning() 

    // Move the message label to the top view 
    view.bringSubviewToFront(messageLabel) 

    // Initialize QR Code Frame to highlight the QR code 
    qrCodeFrameView = UIView() 
    qrCodeFrameView?.layer.borderColor = UIColor.greenColor().CGColor 
    qrCodeFrameView?.layer.borderWidth = 2 
    view.addSubview(qrCodeFrameView!) 
    view.bringSubviewToFront(qrCodeFrameView!) 
}

上線

let input: AnyObject! = AVCaptureDeviceInput.deviceInputWithDevice(captureDevice, error: &error)

我得到的錯誤額外的參數錯誤呼叫。我已經嘗試過使用do {}和catch {}方法，但它不起作用，我總是得到那個錯誤。

我該如何解決這個問題？由於

來源

2015-06-29 markutus

Swift 2的一個新特性是拋出而不是接受'NSError'指針，所以這很可能是你的問題。 – sbarow

@sbarow好筆記！ – fqdn

@sbarow那麼我如何解決這個問題？ – markutus

它看起來並不像這種類型的方法上AVCaptureDeviceInput存在了，看看 - >https://developer.apple.com/library/prerelease/ios/documentation/AVFoundation/Reference/AVCaptureDeviceInput_Class/index.html#//apple_ref/swift/cl/c:objc(cs)AVCaptureDeviceInput

（它看起來像你可能想使用init(device:)）

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來源

2015-06-29 18:54:34 fqdn

那麼我需要在代碼中做什麼更改？ – markutus

@markutus你能找到我鏈接到上面的初始化方法的新簽名？你能解決你的問題嗎？讓我知道你是否需要任何幫助！我鏈接的文檔應該能夠讓你到那裏 – fqdn

Swift 2引入了新的錯誤處理。爲了解決你的問題，你需要catch的錯誤，而不是通過一個NSError對象的AVCaptureDevice方法：

override func viewDidLoad() { 
    super.viewDidLoad() 

    do { 
     let captureDevice = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo) 
     let input = try AVCaptureDeviceInput(device: captureDevice) 
     // Do the rest of your work... 
    } catch let error as NSError { 
     // Handle any errors 
     print(error) 
    } 
}

爲了更深入的解釋來看看這篇文章：

Error Handling in Swift 2.0

來源

2015-06-30 10:21:42 sbarow

Swift 2調用viewdidload中的額外參數錯誤

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