Question

我正在使用ZXing MobileScanner lib和我的iOS for Xamarin项目（MonoTouch）。我设置扫描，它工作正常，读取我的QRCode并得到正确的结果。在阅读了QRCode之后，我想展示另一个ViewController。我在第二个控制器中设置了一个属性，其中包含扫描结果，然后想要显示控制器。

第二个视图未显示在屏幕上。没有错误，没有反馈，根本没有显示。我想，MobileScanner构建了自己的View（可以在lib的源代码中看到）并将其添加到NavigationController中 - 这会导致我的Controller保持“落后”。通过按钮点击简单地重定向到我的控制器进行测试工作正常。我还尝试通过调用scanner.Cancel（）来“处理”视图，但这会导致

Warning: Attempt to dismiss from view controller <UINavigationController: 0x19a0c60> while a presentation or dismiss is in progress!

以下是我的代码，有关如何显示我的观点的任何帮助表示赞赏。

public override void ViewDidLoad ()
    {
        base.ViewDidLoad ();

        // Perform any additional setup after loading the view, typically from a nib.

        scanner = new MobileBarcodeScanner(this.NavigationController);

        this.btnScan.TouchUpInside += (sender, e) => {

            //Tell our scanner to use the default overlay
            scanner.UseCustomOverlay = false;
            //We can customize the top and bottom text of the default overlay
            scanner.TopText = "Ticket vor den Scanner halten";
            scanner.BottomText = "Code wird automatisch eingelesen";

            //Start scanning
            scanner.Scan ().ContinueWith((t) => 
                                         {
                //Our scanning finished callback
                if (t.Status == System.Threading.Tasks.TaskStatus.RanToCompletion){
                    string msg = "";
                    ZXing.Result result = t.Result;

                    if (result != null && !string.IsNullOrEmpty (result.Text)) {

                        scanner.Cancel();

                        if(this.ticketScreen == null) {
                            this.ticketScreen = new TicketScreen();
                        } 

                        this.ticketScreen.ticketUrl = result.Text;
                        this.NavigationController.PushViewController(this.ticketScreen, true);

                    } else {
                        msg = "Code nicht erkannt!";
                        this.InvokeOnMainThread(() => {
                            var av = new UIAlertView("Fehler!", msg, null, "OK", null);
                            av.Show();
                        });
                    }
                }
            });


        };


    }

Answer 1

我使用 this.InvokeOnMainThread（（） ，它在我的代码中运行正常。您的解决方案是：

public override void ViewDidLoad（） { base.ViewDidLoad（）;

    // Perform any additional setup after loading the view, typically from a nib.

    scanner = new MobileBarcodeScanner(this.NavigationController);

    this.btnScan.TouchUpInside += (sender, e) => {

        //Tell our scanner to use the default overlay
        scanner.UseCustomOverlay = false;
        //We can customize the top and bottom text of the default overlay
        scanner.TopText = "Ticket vor den Scanner halten";
        scanner.BottomText = "Code wird automatisch eingelesen";

        //Start scanning
        scanner.Scan ().ContinueWith((t) => 
                                     {
            //Our scanning finished callback
            if (t.Status == System.Threading.Tasks.TaskStatus.RanToCompletion){
                string msg = "";
                ZXing.Result result = t.Result;

                if (result != null && !string.IsNullOrEmpty (result.Text)) {

                    scanner.Cancel();

        this.InvokeOnMainThread(() => 
            {
              if(this.ticketScreen == null) {
                    this.ticketScreen = new TicketScreen();
                } 

                this.ticketScreen.ticketUrl = result.Text;
                this.NavigationController.PushViewController(this.ticketScreen, true);

        });



                } else {
                    msg = "Code nicht erkannt!";
                    this.InvokeOnMainThread(() => {
                        var av = new UIAlertView("Fehler!", msg, null, "OK", null);
                        av.Show();
                    });
                }
            }
        });


    };


}

MonoTouch，ZXing：扫描后重定向到另一个ViewController

1 个答案: