Add missing iOS setLaunchURLsInApp function

Author: nan-li

example/lib/main.dart

@@ -103,6 +103,9 @@ class _MyAppState extends State<MyApp> {
     await OneSignal.shared
         .setAppId("380dc082-5231-4cc2-ab51-a03da5a0e4c2");
 
+    // iOS-only method to open launch URLs in Safari when set to false
+    OneSignal.shared.setLaunchURLsInApp(false);
+
     bool requiresConsent = await OneSignal.shared.requiresUserPrivacyConsent();
 
     this.setState(() {

ios/Classes/OneSignalPlugin.m

@@ -125,6 +125,8 @@ - (void)handleMethodCall:(FlutterMethodCall*)call result:(FlutterResult)result {
         [self disablePush:call withResult:result];
     else if ([@"OneSignal#postNotification" isEqualToString:call.method])
         [self postNotification:call withResult:result];
+    else if ([@"OneSignal#setLaunchURLsInApp" isEqualToString:call.method])
+        [self setLaunchURLsInApp:call withResult:result];
     else if ([@"OneSignal#promptLocation" isEqualToString:call.method])
         [self promptLocation:call withResult:result];
     else if ([@"OneSignal#setLocationShared" isEqualToString:call.method])
@@ -244,6 +246,12 @@ - (void)postNotification:(FlutterMethodCall *)call withResult:(FlutterResult)res
     }];
 }
 
+- (void)setLaunchURLsInApp:(FlutterMethodCall *)call withResult:(FlutterResult)result {
+    BOOL isEnabled = [call.arguments[@"isEnabled"] boolValue];
+    [OneSignal setLaunchURLsInApp:isEnabled];
+    result(nil);
+}
+
 - (void)promptLocation:(FlutterMethodCall *)call withResult:(FlutterResult)result {
     [OneSignal promptLocation];
     result(nil);

lib/onesignal_flutter.dart

@@ -1,4 +1,5 @@
 import 'dart:async';
+import 'dart:io' show Platform;
 import 'package:flutter/services.dart';
 import 'package:onesignal_flutter/src/permission.dart';
 import 'package:onesignal_flutter/src/subscription.dart';
@@ -164,6 +165,19 @@ class OneSignal {
         {'notificationId': notificationId, 'shouldDisplay': shouldDisplay});
   }
 
+  /// Only applies to iOS
+  /// Sets if launch URLs should be opened within the application or in Safari.
+  /// When set to true, launch URLs will open an in-app browser.
+  Future<void> setLaunchURLsInApp(bool isEnabled) async {
+    if (Platform.isIOS) {
+      await _channel.invokeMethod(
+        "OneSignal#setLaunchURLsInApp", {'isEnabled': isEnabled});
+    } else {
+      _onesignalLog(OSLogLevel.info,
+          "setLaunchURLsInApp: this function is not supported on Android");
+    }
+  }
+
   /// Allows you to completely disable the SDK until your app calls the
   /// OneSignal.consentGranted(true) function. This is useful if you want
   /// to show a Terms and Conditions or privacy popup for GDPR.