I'm a iOS dev now writing a react app and got an issue with dotnotation when using parse-server with nested subclassing. Value is always undefined even when data is present.
I am using the JS-SDK (Android and iOS SDK works just fine with similar scenario)
Bike class:
import PriceTier from "./PriceTier";
export default class Bike extends Parse.Object {
constructor() {
super("bike");
}
get price_tier(): PriceTier {
return this.get("price_tier");
}
}
Parse.Object.registerSubclass("bike", Bike);
PriceTier Class
export default class PriceTier extends Parse.Object {
constructor() {
super("price_tier");
}
get standard_price(): number {
return this.get("standard_price");
}
}
Parse.Object.registerSubclass("price_tier", PriceTier);
In a part of my app i do a query and want to read the standard_price like this:
const query = new Parse.Query(Bike);
query.include("price_tier");
const bikes = await query.find();
console.log(bikes[0].price_tier.standard_price) // undefined <-- Why is this undefined when i have a getter in subclass
console.log(bikes[0].price_tier.get("standard_price")) // 100 <-- Why does this work but not above?
Above works perfectly fine in both iOS and Android SDK but not the JS-SDK
So what am i missing or what is the JS-SDK missing?
I am using an ion-loading component which works fine the first time the view is accessed and the loader is presented and dismissed.
import { AlertController, LoadingController } from 'ionic-angular';
constructor(
public zone: NgZone,
public loadingCtrl: LoadingController,
public alertCtrl: AlertController,
private storage: Storage,
public navCtrl: NavController
) {
this.loading = this.loadingCtrl.create();
}
tryGeolocation() {
this.loading.present();
//misc code
this.markers.push(marker);
this.map.setCenter(pos);
//if(this.loading){
this.loading.dismiss();
}
However when I navigate back to the view and the loader is again presented I get a error:
Error: Uncaught (in promise): removeView was not found
I have tried to followe the advice here and introduced checks to see if loader has been dismissed but now the loader never comes into view:
if (this.loading == null){
console.log("Map.ts: Presenting loader.");
this.loading.present();
}
if (this.loading != null){
console.log("Map.ts: Dismissing loader.");
this.loading.dismiss();
}
I am using ionic 3.9.9, angular 5.2.11
Any input appreciated.
Seems to be allot of different solutions out there depending on the context, for me the solution was to move the loader create call from the module constructor to the method calling present and dismiss:
tryGeolocation() {...
this.loading = this.loadingCtrl.create();
this.loading.present();
//some code
this.loading.dismiss();
}
I'm trying to implement google sign in using this component for xamarin.ios: Google Sign-in for iOS
It works great on emulator but when it comes to actual device it's crashing once i tap signin button. (iOS 10.2 - emulator is also using same OS)
I have a custom button which calls SignInUser method on SignIn.SharedInstance
It's crashing with below error (only when the app is deployed on device)
Objective-C exception thrown. Name: NSInvalidArgumentException Reason: uiDelegate must either be a |UIViewController| or implement the |signIn:presentViewController:| and |signIn:dismissViewController:| methods from |GIDSignInUIDelegate|.
I'm calling function below to initialize GoogleSignIn on FinishedLaunching method of AppDelegate.cs
public void Configure()
{
NSError configureError;
Context.SharedInstance.Configure(out configureError);
if (configureError != null)
{
// If something went wrong, assign the clientID manually
Console.WriteLine("Error configuring the Google context: {0}", configureError);
SignIn.SharedInstance.ClientID = googleClientId;
}
SignIn.SharedInstance.Delegate = this;
SignIn.SharedInstance.UIDelegate = new GoogleSignInUIDelegate();
}
Here's my implementation of ISignInUIDelegate():
class GoogleSignInUIDelegate : SignInUIDelegate
{
public override void WillDispatch(SignIn signIn, NSError error)
{
}
public override void PresentViewController(SignIn signIn, UIViewController viewController)
{
UIApplication.SharedApplication.KeyWindow.RootViewController.PresentViewController(viewController, true, null);
}
public override void DismissViewController(SignIn signIn, UIViewController viewController)
{
UIApplication.SharedApplication.KeyWindow.RootViewController.DismissViewController(true, null);
}
}
So the emulator seems to know the methods are implemented, but not the device. Any idea what i am doing wrong here?
After some debugging i found where the actual issue was.
Somehow, the UIDelegate i assigned during initialization was lost when i was calling my login method. So i moved the line below from my initialization step to login
SignIn.SharedInstance.UIDelegate = new GoogleSignInUIDelegate();
Here's how my login method looks like now:
public void Login()
{
SignIn.SharedInstance.UIDelegate = new GoogleSignInUIDelegate(); //moved this here from Configure
SignIn.SharedInstance.SignInUser();
}
This took care of the issue for me but i am still not sure why this is only an issue on the device and not the emulator. Any Ideas?
Add a PreserveAttribute to your GoogleSignInUIDelegate class to prevent the Linker from removing the methods that can not be determined via static analysis.
Add the following class to your project:
public sealed class PreserveAttribute : System.Attribute {
public bool AllMembers;
public bool Conditional;
}
Apply the class attribute:
[Preserve (AllMembers = true)]
class GoogleSignInUIDelegate : SignInUIDelegate
{
~~~~
}
Re: https://developer.xamarin.com/guides/ios/advanced_topics/linker/
Setting PresentingViewController helped me to resolve the issue.
SignIn.SharedInstance.PresentingViewController = this;
Have found such fix here:
https://github.com/googlesamples/google-signin-unity/issues/169#issuecomment-791305225
I am writing an iOS App (using xcode 7.3 and swift 2.2) using JavascriptCode framework. Calling javascript methods from swift works perfect, but when I call the swift method from javascript, xcode simply shows a "loading" type of symbol and nothing happens. I need to "force quit" xcode to get out of this state.
I have followed https://www.raywenderlich.com/124075/javascriptcore-tutorial and http://nshipster.com/javascriptcore/ and I am trying pretty simple calls.
Has anyone faced this kind of issue?
My swift code is as follows:
#objc protocol WindowJSExports : JSExport {
var name: String { get set }
func getName() -> String
static func createWindowWithName(name: String) -> WindowJS
}
#objc class WindowJS : NSObject, WindowJSExports {
dynamic var name: String
init(name: String) {
self.name = name
}
class func createWindowWithName(name: String) -> WindowJS {
return WindowJS(name: name)
}
func getName() -> String {
NSLog("getName called from JS context")
return "\(name)"
}
}
I am initializing the context as follows:
runContext = JSContext()
runContext.name = "test_Context"
windowToJs = WindowJS(name: "test")
runContext.setObject(windowToJs.self, forKeyedSubscript: "WindowJS")
If I replace the last two lines in above code with below code without instantiating it, the code simply fails to load.
runContext.setObject(WindowJS.self, forKeyedSubscript: "WindowJS")
And the javascript code is as simple as
function check() {
return WindowJS.getName()
}
I do see the breakpoint being hit in the JS function check and when the WindowJS.getName gets called, xcode simply becomes unresponsive.
The setTimeout could be solved by adding following piece of code to my swift function.
let setTimeout: #convention(block) (JSValue, Int) -> () =
{ callback, timeout in
let timeVal = Int64(timeout)
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, timeVal), dispatch_get_main_queue(), { callback.callWithArguments(nil)})
}
To expose this native code to the JS context, I also added following.
runContext.setObject(unsafeBitCast(setTimeout, AnyObject.self), forKeyedSubscript: "setTimeout")
Things then worked fine.
You're creating a deadlock since you are calling from Swift to JavaScript back to Swift. I'm not sure exactly why it is a deadlock but I had a similar issue with WKWebView on Mac recently.
You need to decouple this and make the communication asynchronous. This obviously means you cannot simply return a value from your JS function in this case.
To decouple, you can break the deadlock by deferring the work the JavaScript function needs to do out of the current runloop iteration using setTimeout:
function myFunction() {
setTimeout(function() {
// The actual work is done here.
// Call the Swift part here.
}, 0);
}
The whole native ↔︎ JavaScript communication is very, very tricky. Avoid it if you can. There's a project called XWebView that may be able to help you as it tries to ease bridging between the two worlds.
I want to make a Xamarin.Forms project, targeting iOS, Android and Windows Phone.
My app needs to authenticate users using Facebook.
Should I implement login for each platform independently, or use a manual flow?
https://developers.facebook.com/docs/facebook-login/manually-build-a-login-flow/v2.0
I prefer to have a single implementation of the login flow, and use it on all platforms.
How can I get a single implementaion of the Facebook login flow?
UPDATE (10/24/17): While this way of doing things was okay a few years ago, I now strongly advocate for using native UI for doing authentication, as opposed to the webview method shown here. Auth0 is a great way to accomplish native UI login for your apps, using a wide variety of identity providers:
https://auth0.com/docs/quickstart/native/xamarin
EDIT: I finally put a sample for this on Gihub
I posted an answer on the Xamarin Forums. I'll repeat it here.
Let's start with the core of the app, the Xamarin.Forms PCL project. Your App class will look something like this:
namespace OAuth2Demo.XForms
{
public class App
{
static NavigationPage _NavPage;
public static Page GetMainPage ()
{
var profilePage = new ProfilePage();
_NavPage = new NavigationPage(profilePage);
return _NavPage;
}
public static bool IsLoggedIn {
get { return !string.IsNullOrWhiteSpace(_Token); }
}
static string _Token;
public static string Token {
get { return _Token; }
}
public static void SaveToken(string token)
{
_Token = token;
}
public static Action SuccessfulLoginAction
{
get {
return new Action (() => {
_NavPage.Navigation.PopModalAsync();
});
}
}
}
}
The first thing to notice is the GetMainPage() method. This tells the app which screen it should load first upon launching.
We also have a simple property and method for storing the Token that is returned from the auth service, as well as a simple IsLoggedIn property.
There's an Action property as well; something I stuck in here in order to have a way for the platform implementations to perform a Xamarin.Forms navigation action. More on this later.
You'll also notice some red in your IDE because we haven't created the ProfilePage class yet. So, let's do that.
Create a very simple ProfilePage class in the Xamarin.Forms PCL project. We're not even going to do anything fancy with it because that will depend on your particular need. For the sake of simplicity in this sample, it will contain a single label:
namespace OAuth2Demo.XForms
{
public class ProfilePage : BaseContentPage
{
public ProfilePage ()
{
Content = new Label () {
Text = "Profile Page",
VerticalOptions = LayoutOptions.CenterAndExpand,
HorizontalOptions = LayoutOptions.CenterAndExpand,
};
}
}
}
Again, you'll probably have some red in your IDE because we seem to be missing the BaseContentPage class. The sole purpose of the BaseContentPage class is to ensure that none of the app's screens can be displayed until the user has logged in. (In this simplified demo, we're just persisting the user info to memory, so you'll need to re-login every time the app is run. In a real-world app, you'd be storing the authenticated user info to the device's keychain, which would eliminate the need to login at each app start.)
Create a BaseContentPage class in the Xamarin.Forms PCL project:
namespace OAuth2Demo.XForms
{
public class BaseContentPage : ContentPage
{
protected override void OnAppearing ()
{
base.OnAppearing ();
if (!App.IsLoggedIn) {
Navigation.PushModalAsync(new LoginPage());
}
}
}
}
There's a few interesting things going on here:
We're overriding the OnAppearing() method, which is similar to the ViewWillAppear method in an iOS UIViewController. You can execute any code here that you'd like to have run immediately before the screen appears.
The only thing we're doing in this method is checking to see if the user is logged in. If they're not, then we perform a modal push to a class called LoginPage. If you're unfamiliar with the concept of a modal, it's simply a view that takes the user out of the normal application flow in order to perform some special task; in our case, to perform a login.
So, let's create the LoginPage class in the Xamarin.Forms PCL project:
namespace OAuth2Demo.XForms
{
public class LoginPage : ContentPage
{
}
}
Wait...why doesn't this class have a body???
Since we're using the Xamatin.Auth component (which does the job of building and presenting a web view that works with the provided OAuth2 info), we actually don't want any kind of implementation in our LoginPage class. I know that seems weird, but bear with me.
The LoginPageRenderer for iOS
Up until this point, we've been working solely in the Xamarin.Forms PCL project. But now we need to provide the platform-specific implementation of our LoginPage in the iOS project. This is where the concept of a Renderer comes in.
In Xamarin.Forms, when you want to provide platform-specific screens and controls (i.e. screens that do not derive their content from the abstract pages in the Xamarin.Forms PCL project), you do so with Renderers.
Create a LoginPageRenderer class in your iOS platform project:
[assembly: ExportRenderer (typeof (LoginPage), typeof (LoginPageRenderer))]
namespace OAuth2Demo.XForms.iOS
{
public class LoginPageRenderer : PageRenderer
{
public override void ViewDidAppear (bool animated)
{
base.ViewDidAppear (animated);
var auth = new OAuth2Authenticator (
clientId: "", // your OAuth2 client id
scope: "", // the scopes for the particular API you're accessing, delimited by "+" symbols
authorizeUrl: new Uri (""), // the auth URL for the service
redirectUrl: new Uri ("")); // the redirect URL for the service
auth.Completed += (sender, eventArgs) => {
// We presented the UI, so it's up to us to dimiss it on iOS.
App.SuccessfulLoginAction.Invoke();
if (eventArgs.IsAuthenticated) {
// Use eventArgs.Account to do wonderful things
App.SaveToken(eventArgs.Account.Properties["access_token"]);
} else {
// The user cancelled
}
};
PresentViewController (auth.GetUI (), true, null);
}
}
}
}
There are important things to note:
The [assembly: ExportRenderer (typeof (LoginPage), typeof (LoginPageRenderer))] line at the top (and importantly before the namespace declaration) is using the Xamarin.Forms DependencyService. It's not the most beautiful thing in the world because it's not IoC/DI, but whatever...it works. This is the mechanism that "maps" our LoginPageRenderer to the LoginPage.
This is the class in which we're actually using the Xamarin.Auth component. That's where the OAuth2Authenticator reference comes from.
Once the login is successful, we fire off a Xamarin.Forms navigation via App.SuccessfulLoginAction.Invoke();. This gets us back to the ProfilePage.
Since we're on iOS, we're doing all of our logic sinde of the ViewDidAppear() method.
The LoginPageRenderer for Android
Create a LoginPageRenderer class in your Android platform project. (Note that class name you're creating is identical to the one in the iOS project, but here in the Android project the PageRenderer inherits from Android classes instead of iOS classes.)
[assembly: ExportRenderer (typeof (LoginPage), typeof (LoginPageRenderer))]
namespace OAuth2Demo.XForms.Android
{
public class LoginPageRenderer : PageRenderer
{
protected override void OnModelChanged (VisualElement oldModel, VisualElement newModel)
{
base.OnModelChanged (oldModel, newModel);
// this is a ViewGroup - so should be able to load an AXML file and FindView<>
var activity = this.Context as Activity;
var auth = new OAuth2Authenticator (
clientId: "", // your OAuth2 client id
scope: "", // the scopes for the particular API you're accessing, delimited by "+" symbols
authorizeUrl: new Uri (""), // the auth URL for the service
redirectUrl: new Uri ("")); // the redirect URL for the service
auth.Completed += (sender, eventArgs) => {
if (eventArgs.IsAuthenticated) {
App.SuccessfulLoginAction.Invoke();
// Use eventArgs.Account to do wonderful things
App.SaveToken(eventArgs.Account.Properties["access_token"]);
} else {
// The user cancelled
}
};
activity.StartActivity (auth.GetUI(activity));
}
}
}
Again, let's take a look at some interesting things:
The [assembly: ExportRenderer (typeof (LoginPage), typeof (LoginPageRenderer))] line at the top (and importantly before the namespace declaration) is using the Xamarin.Forms DependencyService. No difference here from the iOS version of LoginPageRenderer.
Again, this is where we're actually using the Xamarin.Auth component. That's where the OAuth2Authenticator reference comes from.
Just as with the iOS version, once the login is successful, we fire off a Xamarin.Forms navigation via App.SuccessfulLoginAction.Invoke();. This gets us back to the ProfilePage.
Unlike the iOS version, we're doing all of the logic inside of the OnModelChanged() method instead of the ViewDidAppear().
Here it is on iOS:
...and Android:
UPDATE:
I've also provided a detailed sample at my blog: http://www.joesauve.com/using-xamarin-auth-with-xamarin-forms/
You could consume either Xamarin.Social or Xamarin.Auth for that. It allows using the same api whatever the platform is.
As of now, those libs aren't PCL yet, but you still can consume them from a Shared Assets Project, or abstract the API you need in an interface and inject in with DependencyService or any other DI container.
I've created a sample project to show how to create a Facebook login using native Facebook component, not through a webview like the solutions suggested here.
You can check it out in this address:
https://github.com/IdoTene/XamarinFormsNativeFacebook
IOS 8: For those who are using #NovaJoe code and are stuck on view, add the code bellow to workaround:
bool hasShown;
public override void ViewDidAppear(bool animated)
{
if (!hasShown)
{
hasShown = true;
// the rest of #novaJoe code
}
}
Here's a good Xamarin.Forms authentication sample. The documentation in the code is nice. It uses a webview to render the login screen, but you can select what login type you want. It also saves a users token so he doesn't have to keep re-logging in.
https://github.com/rlingineni/Xamarin.Forms_Authentication
Another addition to #NovaJoe's code, on iOS8 with Facebook, you'd need to modify the Renderer class as below to close the View after successful authentication.
auth.Completed += (sender, eventArgs) => {
// We presented the UI, so it's up to us to dimiss it on iOS.
/*Importand to add this line */
DismissViewController (true, null);
/* */
if (eventArgs.IsAuthenticated) {
App.Instance.SuccessfulLoginAction.Invoke ();
// Use eventArgs.Account to do wonderful things
App.Instance.SaveToken (eventArgs.Account.Properties ["access_token"]);
} else {
// The user cancelled
}
};
The correct implementation for the Androids PageRenderer is:
using System;
using Android.App;
using Android.Content;
using OAuth2Demo.XForms.Android;
using Xamarin.Auth;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;
using XamarinAuth;
[assembly: ExportRenderer(typeof(LoginPage), typeof(LoginPageRenderer))]
namespace OAuth2Demo.XForms.Android
{
public class LoginPageRenderer : PageRenderer
{
public LoginPageRenderer(Context context) : base(context) { }
protected override void OnElementChanged(ElementChangedEventArgs<Page> e)
{
base.OnElementChanged(e);
// this is a ViewGroup - so should be able to load an AXML file and FindView<>
var activity = this.Context as Activity;
var auth = new OAuth2Authenticator(
clientId: "<Constants.clientId>", // your OAuth2 client id
scope: "<Constants.scope>", // the scopes for the particular API you're accessing, delimited by "+" symbols
authorizeUrl: new Uri("<Constants.authorizeUrl>"), // the auth URL for the service
redirectUrl: new Uri("<Constants.redirectUrl>")); // the redirect URL for the service
auth.Completed += (sender, eventArgs) =>
{
if (eventArgs.IsAuthenticated)
{
App.SuccessfulLoginAction.Invoke();
// Use eventArgs.Account to do wonderful things
App.SaveToken(eventArgs.Account.Properties["access_token"]);
}
else
{
// The user cancelled
}
};
activity.StartActivity(auth.GetUI(activity));
}
}
}