Merge pull request #1234 from xamarin/develop

Late 1.5.3 fix for WebAuthenticator

Author: Redth

Xamarin.Essentials/WebAuthenticator/WebAuthenticator.ios.tvos.cs

@@ -24,6 +24,10 @@ public static partial class WebAuthenticator
         static TaskCompletionSource<WebAuthenticatorResult> tcsResponse;
         static UIViewController currentViewController;
         static Uri redirectUri;
+#if __IOS__
+        static ASWebAuthenticationSession was;
+        static SFAuthenticationSession sf;
+#endif
 
         internal static async Task<WebAuthenticatorResult> PlatformAuthenticateAsync(Uri url, Uri callbackUrl)
         {
@@ -55,7 +59,7 @@ void AuthSessionCallback(NSUrl cbUrl, NSError error)
 
                 if (UIDevice.CurrentDevice.CheckSystemVersion(12, 0))
                 {
-                    var was = new ASWebAuthenticationSession(new NSUrl(url.OriginalString), scheme, AuthSessionCallback);
+                    was = new ASWebAuthenticationSession(new NSUrl(url.OriginalString), scheme, AuthSessionCallback);
 
                     if (UIDevice.CurrentDevice.CheckSystemVersion(13, 0))
                     {
@@ -64,14 +68,20 @@ void AuthSessionCallback(NSUrl cbUrl, NSError error)
                     }
 
                     was.Start();
-                    return await tcsResponse.Task;
+                    var result = await tcsResponse.Task;
+                    was?.Dispose();
+                    was = null;
+                    return result;
                 }
 
                 if (UIDevice.CurrentDevice.CheckSystemVersion(11, 0))
                 {
-                    var sf = new SFAuthenticationSession(new NSUrl(url.OriginalString), scheme, AuthSessionCallback);
+                    sf = new SFAuthenticationSession(new NSUrl(url.OriginalString), scheme, AuthSessionCallback);
                     sf.Start();
-                    return await tcsResponse.Task;
+                    var result = await tcsResponse.Task;
+                    sf?.Dispose();
+                    sf = null;
+                    return result;
                 }
 
                 // THis is only on iOS9+ but we only support 10+ in Essentials anyway