I work on a Flutter mobile app and I want to detect the first app launch to show a little tutorial to the user. I have tests the Shared-Preferences Module But when If I start the app for the first time The console tells me the key is not recognized, I think it's normal because this key does exist! There is another method for checking that?
Thank you guys
use shared preferences to store value that indicate if user has ever been in this page or not
like this
try {
final SharedPreferences sharedPreferences = await SharedPreferences.getInstance();
splash = sharedPreferences.getString("SPLASH_DONE");
} catch (e) {
print("this is first time");
}
if (splash == null) {
page = AppSplashScreen();
} else {
page = LoginPage();
}
and after completing your first time operation call
sharedPreferences.setString("SPLASH_DONE", "DONE");
Related
I want to edit my active subscription and for this I need to go to the play store.
Forcing the user to open the play store first, and then go to the settings page, and then open subscriptions is not suitable. Can this be done somehow in 1 click (not in browser)?
Options with opening in the browser are not suitable. I need to open the page with all subscriptions (https://play.google.com/store/account/subscriptions)
I need a redirect link market://...
Thank you!
I tried next packages: url_launcher, store_redirect etc.
Methods like: `
final Uri url =
Uri.parse('https://apps.apple.com/app/MyAppName/idXXXXX');
try {
if (await canLaunch(url.toString())) {
await launch(url.toString());
} else {
throw 'Could not launch $url';
}
} catch (e) {
print(e);
}
and
launchUrl(Uri.parse('https://play.google.com/store/account/subscriptions?sku=pro.monthly.testsku&package=com.example.app'));
I had to use only this method:
final url = Uri.parse('http://play.google.com/store/account/subscriptions');
Here is my challenge:
I'm using the following example from https://firebase.flutter.dev/docs/storage/usage/
to upload images to my FireBaseStorage from my phone gallery (which delivers me the String filepath-variable).
Future<void> handleTaskExample2(String filePath) async {
File largeFile = File(filePath);
firebase_storage.UploadTask task = firebase_storage.FirebaseStorage.instance
.ref('uploads/picture-to-upload.jpeg')
.putFile(largeFile);
task.snapshotEvents.listen((firebase_storage.TaskSnapshot snapshot) {
print('Task state: ${snapshot.state}');
print(
'Progress: ${(snapshot.bytesTransferred / snapshot.totalBytes) * 100} %');
}, onError: (e) {
print(task.snapshot);
if (e.code == 'permission-denied') {
print('User does not have permission to upload to this reference.');
}
});
try {
await task;
print('Upload complete.');
} on firebase_core.FirebaseException catch (e) {
if (e.code == 'permission-denied') {
print('User does not have permission to upload to this reference.');
}
// ...
}
}
Actually, everything works fine. My uploaded Image to my Storage gets shown in my GridView inside the App...
But if I upload an Image to my Storage manually over the FireBase Website, my gridView (where the pictures from my storage are shown) is not auto-updating.
But if I change my screen and come back, the manually uploaded picture is shown.
It looks like I need something like a StreamBuilder that my App gets informed whenever changes happen in my Storage.
Does anyone have an Idea how to implement this or any other ideas to solve my problem?
Thanks
The listAll and list only get the data once so you unfortunately can't have a stream on them. You have 2 options here.
Call the listAll in a periodic interval like every 2-3 min
Create a cloud functions that get's triggered when files get uploaded to that specific directory and change a value in RTDB or Firestore. In the App you can listen to that data. Idealy it should be just a timestamp. You can store in your app the last timestamp you got from the database and if that changes just call listAll.
It depends on your usecase what would fit for you the best.
I have a messaging app that receives push notification from Firebase Cloud Messaging and when it does, it pushes it to a stream. In order to keep track of different streams, I have a streamtable which is a global variable. This is what I have
Map<String, StreamController<dynamic>> streamtable;
Future<dynamic> myBackgroundMessageHandler(Map<String, dynamic> message) async {
log('FCM onBackground: $message');
log('streamTable: $streamtable');
addToStream(message);
await showNotification(message);
return;
}
bool addToStream(Map<String, dynamic> message) {
var data;
if (Platform.isAndroid) {
data = message['data'];
} else if (Platform.isIOS) {
data = message;
}
bool status;
try {
switch (data['streamType']) {
case "Message":
streamtable['MessageStream'].add(message);
status = true;
break;
default:
log("streamType: ${data['streamType']}");
status = false;
break;
}
} catch (e) {
status = false;
log('addToStream: error($e)');
}
return status;
}
When the app is in the foreground, everything works great. However, when the app is in the background, streamtable becomes null, and nothing works.
First off, why is that happening? If I bring the app back to foreground, streamtable is not null.
How do I store data I receive when the app is in the background?
Mobile systems work differently than desktop systems. For desktop systems, "in the background" just means the UI is not on top, but the program is running. For mobile systems, "in the background" means the app is not used and as such can be killed by the operating system any time it sees fit.
Different systems have different callbacks to notify the app of impeding shutdown so it can write it's last data to a storage and restore from that state when it's called again.
The thought that your app holds global data and retains it in memory, since it's running, just "in the background" is not correct. It won't. It can be gone any time on mobile systems.
You will need to actually save the data you want to restore later, the "memory" only lasts as long as it's in the foreground or the operating system feels generous.
Seems like it's a bug in flutter: (https://github.com/FirebaseExtended/flutterfire/issues/1878)
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'm using the Plugin.Media from #JamesMontemagno version 2.4.0-beta (which fixes picture orientation), it's working on Adroind 4.1.2 (Jelly Bean) and Marshmallow, but NOT on my Galaxy S5 Neo with Android version 5.1.1.
Basically when I take a picture it never returns back on the page from where I started the process; always returns back to the initial home page.
On devices where it works, when I take a picture, I see that first of all the application fires OnSleep, then after taking the picture fires OnResume.
On my device where is NOT working it fires OnSleep and after taking the picture doesn't fire OnResume, it fires the initialization page and then OnStart.
For this reason it doesn't open the page where I was when taking the picture.
What should I do to make sure it fires OnResume returning to the correct page and not OnStart which returns on initial fome page ?
In addition, when I take a picture it takes almost 30 seconds to get back to the code after awaiting TakePhotoAsync process, and it's too slow!
Following my code:
MyTapGestureRecognizerEditPicture.Tapped += async (sender, e) =>
{
//Display action sheet
String MyActionResult = await DisplayActionSheet(AppLocalization.UserInterface.EditImage,
AppLocalization.UserInterface.Cancel,
AppLocalization.UserInterface.Delete,
AppLocalization.UserInterface.TakePhoto,
AppLocalization.UserInterface.PickPhoto);
//Execute action result
if (MyActionResult == AppLocalization.UserInterface.TakePhoto)
{
//-----------------------------------------------------------------------------------------------------------------------------------------------
//Take photo
await CrossMedia.Current.Initialize();
if (!CrossMedia.Current.IsCameraAvailable || !CrossMedia.Current.IsTakePhotoSupported)
{
await DisplayAlert(AppLocalization.UserInterface.Alert, AppLocalization.UserInterface.NoCameraAvailable, AppLocalization.UserInterface.Ok);
}
else
{
var MyPhotoFile = await CrossMedia.Current.TakePhotoAsync(new Plugin.Media.Abstractions.StoreCameraMediaOptions
{
Directory = "MyApp",
Name = "MyAppProfile.jpg",
SaveToAlbum = true,
PhotoSize = Plugin.Media.Abstractions.PhotoSize.Small
});
if (MyPhotoFile != null)
{
//Render image
MyProfilePicture.Source = ImageSource.FromFile(MyPhotoFile.Path);
//Save image on database
MemoryStream MyMemoryStream = new MemoryStream();
MyPhotoFile.GetStream().CopyTo(MyMemoryStream);
byte[] MyArrBytePicture = MyMemoryStream.ToArray();
await SaveProfilePicture(MyArrBytePicture);
MyPhotoFile.Dispose();
MyMemoryStream.Dispose();
}
}
}
if (MyActionResult == AppLocalization.UserInterface.PickPhoto)
{
//-----------------------------------------------------------------------------------------------------------------------------------------------
//Pick photo
await CrossMedia.Current.Initialize();
if (!CrossMedia.Current.IsPickPhotoSupported)
{
await DisplayAlert(AppLocalization.UserInterface.Alert, AppLocalization.UserInterface.PermissionNotGranted, AppLocalization.UserInterface.Ok);
}
else
{
var MyPhotoFile = await CrossMedia.Current.PickPhotoAsync();
if (MyPhotoFile != null)
{
//Render image
MyProfilePicture.Source = ImageSource.FromFile(MyPhotoFile.Path);
//Save image on database
MemoryStream MyMemoryStream = new MemoryStream();
MyPhotoFile.GetStream().CopyTo(MyMemoryStream);
byte[] MyArrBytePicture = MyMemoryStream.ToArray();
await SaveProfilePicture(MyArrBytePicture);
MyPhotoFile.Dispose();
MyMemoryStream.Dispose();
}
}
}
};
Please help!! We need to deploy this app but we cannot do it with this problem.
Thank you in advance!
It is perfectly normal to have the Android OS terminate and restart an Activity. As you are seeing, your app's Activity it will be automatically restarted when the camera app exits and the OS returns control to your app. The odds are it just needed more memory in order to take that photo with the Neo's 16MP camera, you can watch the logcat output to confirm that.
Restarted – It is possible for an activity that is anywhere from paused to stopped in the lifecycle to be removed from memory by Android. If the user navigates back to the activity it must be restarted, restored to its previously saved state, and then displayed to the user.
What to do:
So on the Xamarin.Forms OnStart lifecycle method you need to restore your application to a valid running state (initializing variables, preforming any bindings, etc...).
Plug code:
The Android platform code for the TakePhotoAsync method looks fine to me, but remember that the memory for that image that is passed back via the Task will be doubled as it is marshaled from the ART VM back the Mono VM. Calling GC.Collect() as soon as possible after the return will help (but your Activity is restarting anyway...)
public async Task<MediaFile> TakePhotoAsync(StoreCameraMediaOptions options)
{
~~~
var media = await TakeMediaAsync("image/*", MediaStore.ActionImageCapture, options);
In turn calls:
this.context.StartActivity(CreateMediaIntent(id, type, action, options));
Not much less you can really do within the Android OS to popup the Camera.
In addition, when I take a picture it takes almost 30 seconds to get back to the code after awaiting TakePhotoAsync process, and it's too slow!
Is that on your Neo? Or all devices?
I would call that very suspect (ie. a bug) as even flushing all the Java memory after the native Camera Intent/Activity and the restart time for your app's Activity should not take 30 seconds on a oct-core 1.6 GHz Cortex... but I do not have your device, app and code in front of me....