I'm trying to throw Webview.GoBack() method in a UWP application.
The WebView is presenting PayPal page and I want to return to another page.
When I throw WebView.GoBack() only works at second time. Why??
My code is:
if (webView.CanGoBack)
{
webView.GoBack();
}
No exception is thrown..
Related
I currently have this:
.onReceive(NotificationCenter.default.publisher(for: UIApplication.willEnterForegroundNotification)) { _ in
...
}
and that works when I don't quit the app, it simply is in the background, but when I quit it, the code inside there that is suppoused to check for a time, doesn't work.
I also tried putting it in
.onAppear() {
but that doesn't workout either :/
How can I once the app has been closed, then opened, as soon as it opens run an action?
you could try adding the following code to perform an action when your app starts:
.onReceive(NotificationCenter.default.publisher(for: UIApplication.didBecomeActiveNotification)) { _ in
// do your action here
....
}
I am making an application that allows me to scan QR codes, and I managed to make the code work but my doubt is that when I scan the plugin phonegap-plugin-barcodescanner takes me out of the camera interface, what I want to do is to stay in it and show me an alert with the scanned code, and to give it ok in the alert to stay in it, to avoid being clicked to enter it.
I'm working with the plugin phonegap-plugin-barcodescanner, in ionic 3
public scanQR2() {
this._ButtonText = "Escanear";
this._barcodeScanner.scan().then((barcodeData) => {
if (barcodeData.cancelled) {
console.log("User cancelled the action!");
this._ButtonText = "Escanear";
return false;
}
console.log("Scanned successfully!");
console.log(barcodeData);
}, (err) => {
console.log(err);
});
}
I hope that the application when performing a scan stays on the same interface and does not redirect me to another page
I am developing an app in Xamarin.Forms, before I was trying to make a master detail page to become my MainPage when I logged in to my app, this I have already achieved. Now I have the problem that when I use the button behind the phone my app is miimiza and goes to the background which is the behavior I hope, but when I return to my app does not continue showing my master detail page, but returns to my LginPage.
It is as if my app was running twice or at least there were two instances of LoginPage existing at the same time, this is because in my LoginPage I trigger some DisplayAlert according to some messages that my page is listening through the MessaginCenter and they are they shoot twice.
Can someone tell me how I can return the same to my app on the master detail page and not restart in the strange way described?
LoginView.xaml.cs:
public partial class LogonView : ContentPage
{
LogonViewModel contexto = new LogonViewModel();
public LogonView ()
{
InitializeComponent ();
BindingContext = contexto;
MessagingCenter.Subscribe<LogonViewModel>(this, "ErrorCredentials", async (sender) =>
{
await DisplayAlert("Error", "Email or password is incorrect.", "Ok");
}
);
}
protected override void OnDisappearing()
{
base.OnDisappearing();
MessagingCenter.Unsubscribe<LogonViewModel>(this, "ErrorCredentials");
}
}
Part of my ViewModel:
if (Loged)
{
App.token = token;
Application.Current.MainPage = new RootView();
}
else
{
MessagingCenter.Send(this, "ErrorCredentials");
}
Thanks.
I hope this is in Android. All you can do is, you can override the backbuttonpressed method in MainActivity for not closing on back button pressed of the entry page. like below, you can add some conditions as well.
public override void OnBackPressed()
{
Page currentPage = Xamarin.Forms.Application.Current.MainPage.Navigation.NavigationStack.LastOrDefault();
if (currentPage != null)
{
if (currentPage.GetType().Name == "HomePage" || currentPage.GetType().Name == "LoginPage")
{
return;
}
}
base.OnBackPressed();
}
When you press the Home button, the application is paused and the
current state is saved, and finally the application is frozen in
whatever state it is. After this, when you start the app, it is
resumed from the last point it was saved with.
However, when you use the Back button, you keep traversing back in
the activity stack, closing one activity after another. in the end,
when you close the first activity that you opened, your application
exits. This is why whenever you close your application like this, it
gets restarted when you open it again.
Answer taken from this answer. The original question asks about the native Android platform, but it still applies here.
It means you have to Use Setting Plugin or save data in Application properties.
You have to add below code in App.xaml.cs file:
if (SettingClass.UserName == null)
MainPage = new LoginPage();
else
MainPage = new MasterDetailPage();
For Setting Plugin you can refer this link.
I have a slightly odd issue and unfortunately it's not one I can easily write a standalone class for.
Within my application I have a TableView (on a tab) which is clickable. Clicking on a row in this TableView opens a new Tab with a data relating to the clicked row in a new TableView.
The TableViews are bound to a custom class that extends ModifiableObservableListBase. This allows a Scrollbar to be used to request new data from the server based on the top and bottom rows of the viewport.
This all works well.
I also have a Service in my subclass of ModifiableObservableListBase that is used to improve the rendering of data under high load. It uses a LinkedBlockingQueue and countDownLatch so that only most recent view is updated to the UI preventing unnecessary redraws. Using the following:
setAll(list);
This also works well.
So far so good!
What I've noticed is that when I open and close these tabs multiple times (no fixed number), at some point the TableView will stop updating with data. The data is requested from the server and received but the Service which is used to control how data is added to the ModifiableObservableListBase fails to move out of the SCHEDULED state. This means that the Task that has been created never runs. I'm struggling to see why this would work correctly x times and then stop working.
Any help would be really welcomed, sorry I don't have a standaone application that replicates this issue. I will try to recreate it.
The following Service is constructed in the constructor of my subclass of ModifiableObservableListBase which is constructed each time a new tab(including the corresponding TableView which is bound to the ModifiableObservableListBase ) is added to the UI.
Service upDateService = new Service() {
#Override
protected Task createTask() {
//when the code fails it still calls to here.
return new Task() {
#Override
protected Object call() throws Exception {
//when the code fails it doesn't call the call() method
while (true) {
List<T> list = updateQueue.take();
updateLatch = new CountDownLatch(1);
//now put on the FX Application Thread
Platform.runLater(() -> {
if (list.size() > 0 && list.get(0) instanceof TableStructure) {
totalRowCount.set(((TableStructure) list.get(0)).getTotalDbRowCount());
}
setAll(list);
updateLatch.countDown();
});
try {
updateLatch.await(1, TimeUnit.MINUTES);
updateLatch = null;
}
catch (InterruptedException ex) {
ex.printStackTrace();
}
}
}
};
}
};
upDateService.start();
Inside MainpPage.xaml.cs, what callback can be used so that I know it is coming from launching the App but not coming from other page? I know that there is Application_Launching in App.xaml.cs. But if I place below code there, exception is thrown somewhere. If I put in Loaded callback, I can't distinguish if it is called from App launching from navigated from other page.
if (MediaPlayer.State == MediaState.Playing)
{
MediaPlayer.Pause();
}
I would like to stop any existing playing music after entering my app.
Thanks
In you App.xaml:
public void TryStopAllMusic()
{
if (MediaPlayer!=null && MediaPlayer.GameHasControl)
{
MediaPlayer.Stop(); //stop to clear any existing music
}
}
In the constructor, under InitializeComponent() of your MainPage.xaml.cs:
public MainPage()
{
InitializeComponent();
(Application.Current as App).TryStopAllMusic();
}
That's all.