Add splash screen to ios

ios/app/Images.xcassets/Contents.json

@@ -1,6 +1,6 @@
 {
   "info" : {
-    "version" : 1,
-    "author" : "xcode"
+    "author" : "xcode",
+    "version" : 1
   }
 }

ios/app/Images.xcassets/LaunchScreen.imageset/Contents.json

@@ -0,0 +1,23 @@
+{
+  "images" : [
+    {
+      "filename" : "splash.jpg",
+      "idiom" : "universal",
+      "scale" : "1x"
+    },
+    {
+      "filename" : "splash@2x.jpg",
+      "idiom" : "universal",
+      "scale" : "2x"
+    },
+    {
+      "filename" : "splash@3x.jpg",
+      "idiom" : "universal",
+      "scale" : "3x"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}