Fix For iOS

lib/file_manager/file_manager_init.dart

@@ -19,22 +19,24 @@ checkPermission() {
     //整个Flutter App的入口03
     bool ret = await getPermission();
     if (ret) {
-      //整个Flutter App的入口04
-      getSDCardDir().then((value) {
-        //整个Flutter App的入口05
-        //runApp(MyApp());
-        runApp(MaterialApp(
-          //title: '启动图demo',
-          debugShowCheckedModeBanner: false,
-          theme: new ThemeData(
-              brightness: Brightness.light,
-              backgroundColor: Colors.white,
-              platform: TargetPlatform.android),
-          home: new SplashScreen(), //整个Flutter App的入口06
-          //整个Flutter App的入口07
-          routes: <String, WidgetBuilder>{'/home': (BuildContext context) => MyApp()},
-        ));
-      });
+      var app = runApp(MaterialApp(
+        debugShowCheckedModeBanner: false,
+        theme: new ThemeData(
+            brightness: Brightness.light,
+            backgroundColor: Colors.white,
+            platform: TargetPlatform.android),
+        home: new SplashScreen(),
+        routes: <String, WidgetBuilder>{
+          '/home': (BuildContext context) => MyApp()
+        },
+      ));
+      if (Platform.isAndroid) {
+        getSDCardDir().then((value) {
+          app;
+        });
+      } else if (Platform.isIOS) {
+        app;
+      }
     } else {
       Fluttertoast.showToast(msg: '用户未授权，程序无法正常运行！', gravity: ToastGravity.CENTER);
       SystemChannels.platform.invokeMethod('SystemNavigator.pop');