今天會介紹 生命週期裡要如何宣告

1. viewDidLoad
   在 viewDidLoad 裡呼叫掃描 QRCode 的 function

   override func viewDidLoad() {
   	super.viewDidLoad()
   	scanQRCode()
   }
   

2. viewWillAppear
   在 viewWillAppear 裡確定掃瞄器有開啟

   override func viewWillAppear(_ animated: Bool) {
   	super.viewWillAppear(animated)
   	captureSession?.commitConfiguration()
   	// 判斷 AVCaptureSession 的接收器是否正在執行
   	if (captureSession?.isRunning == false) {
   		captureSession?.startRunning()
   	}
   }
   

3. viewWillDisappear
   在 viewWillDisappear 裡關閉掃瞄器，避免其在背景依舊執行掃描的動作

   override func viewWillDisappear(_ animated: Bool)
   {
   	super.viewWillDisappear(animated)
   	if (captureSession?.isRunning == true) {
   		captureSession?.stopRunning()
   	}
   }
   

明天將會繼續介紹 AVCaptureVideoPreviewLayer！拭目以待！

GitHub - AVCaptureVideoPreviewLayerDemo