Локаль можно задать на этапе сборки

lib/purchase.dart

@@ -31,24 +31,24 @@ class PurchaseScreenState<T> extends BaseState<PurchaseScreen> {
   PurchaseScreenState(String userString, String card) {
     this.user = JSON.decode(userString);
     this.card = card;
-    getLoyality(user['loyalty_url']);
+    getLoyalty(user['loyalty_url']);
   }
 
   bool purchaseInProgress = false;
   Map user;
   String card = '';
-  String loyality = '';
+  String loyalty = '';
 
   @override Widget getScreenContent() {
     return new Column(
       children: <Widget>[new Expanded(child: new ListView(children: <Widget>[
-        getValueWithDescription(Strings.of(context).userName(), user['first_name'] == null ? '' : user['first_name']),
-        getValueWithDescription(Strings.of(context).card(), card),
-        getValueWithDescription(Strings.of(context).reward(), loyality),
+        getValueWithDescription(StringsLocalization.userName(), user['first_name'] == null ? '' : user['first_name']),
+        getValueWithDescription(StringsLocalization.card(), card),
+        getValueWithDescription(StringsLocalization.reward(), loyalty),
         getHintLabel(),
         getInputField(),
-        buildButton(getScreenMargins(36.0), getCompleteButton()),
-        buildButton(getScreenMargins(24.0), getScanButton(context, Strings.of(context).scan(), primaryColor))
+        wrapButton(getScreenMargins(36.0), getCompleteButton()),
+        wrapButton(getScreenMargins(24.0), getScanButton(context, StringsLocalization.scan(), primaryColor))
       ]))]);
   }
 
@@ -58,8 +58,7 @@ class PurchaseScreenState<T> extends BaseState<PurchaseScreen> {
   }
 
   getCompleteButton() {
-    String title = Strings.of(context).completePurchase();
-    return buildRaisedButton(context, title, () => onPurchaseClick(context));
+    return buildRaisedButton(StringsLocalization.completePurchase(), () => onPurchaseClick());
   }
 
   Widget getScanButton(BuildContext context, String title, Color textColor) {
@@ -76,21 +75,17 @@ class PurchaseScreenState<T> extends BaseState<PurchaseScreen> {
   }
 
   @override String getTitle() {
-    return Strings.of(context).carryingPurchase();
+    return StringsLocalization.carryingPurchase();
   }
 
   @override getHint() {
-    return Strings.of(context).sum();
+    return StringsLocalization.sum();
   }
 
-  @override getMenuButtons(BuildContext context) {
+  @override getMenuButtons() {
     return <Widget>[getFaqButton(), getLogoutButton()];
   }
 
-  @override Color getTextFilledBackground() {
-    return Colors.white;
-  }
-
   @override getTextWidget() {
     return new TextField(
         keyboardType: TextInputType.number,
@@ -109,10 +104,12 @@ class PurchaseScreenState<T> extends BaseState<PurchaseScreen> {
     );
   }
 
-  getLoyality(String url) async {
+  getLoyalty(String url) async {
 
     if (await platform.invokeMethod('isOnline')) {
 
+      String token = await platform.invokeMethod('getToken');
+
       var headers = {
         'DM-Authorization': 'dmapptoken $appToken',
         'Authorization': 'dmtoken ${token}'
@@ -126,11 +123,11 @@ class PurchaseScreenState<T> extends BaseState<PurchaseScreen> {
         String type = bonuses['type'];
         setState(() {
           if (type == 'amount') {
-            this.loyality = '${user['discount']}%';
+            this.loyalty = '${user['discount']}%';
           } else {
             List amountToBonus = bonuses['amount_to_bonus'];
             double loyalityVal = (double.parse(amountToBonus[1]) / amountToBonus[0]) * 100;
-            this.loyality = '${loyalityVal.toStringAsFixed(0)}%';
+            this.loyalty = '${loyalityVal.toStringAsFixed(0)}%';
           }
         });
       }).catchError((error) {
@@ -175,20 +172,20 @@ class PurchaseScreenState<T> extends BaseState<PurchaseScreen> {
     return sumTotal.toStringAsFixed(2);
   }
 
-  onPurchaseClick(BuildContext context) {
+  onPurchaseClick() {
     String val = _parseSum(controller.text);
     showDialog(context: context, child: new AlertDialog(
-      title: new Text(Strings.of(context).confirmation()),
-      content: new Text(getContentMessage(val)),
+      title: new Text(StringsLocalization.confirmation()),
+      content: new Text(StringsLocalization.confirmPurchase(val)),
       actions: <Widget>[
         new FlatButton(
-          child: new Text(Strings.of(context).no()),
+          child: new Text(StringsLocalization.no()),
           onPressed: () {
             Navigator.of(context).pop();
           },
         ),
         new FlatButton(
-          child: new Text(Strings.of(context).yes()),
+          child: new Text(StringsLocalization.yes()),
           onPressed: () {
             purchase(val);
           },
@@ -196,14 +193,12 @@ class PurchaseScreenState<T> extends BaseState<PurchaseScreen> {
       ]));
   }
 
-  getContentMessage(String val) {
-    return Strings.of(context).confirmPurchase();
-  }
-
   purchase(String sumTotal) async {
     if (await platform.invokeMethod('isOnline')) {
       if (!purchaseInProgress) {
         purchaseInProgress = true;
+
+        String token = await platform.invokeMethod('getToken');
         platform.invokeMethod('getDocID').then((result) {
 
             String url = user['purchases_url'];