call setScreenSize once instead of multiple times

Author: rundmt

src/components/Column.js

@@ -1,7 +1,7 @@
 'use strict';
 
 import React from 'react-native';
-import {setScreenSize} from '../lib/ScreenSize';
+import {screenSize} from '../lib/ScreenSize';
 
 var {
   Component,
@@ -14,7 +14,7 @@ var {
 export default class Column extends Component {
   constructor(props){
     super(props);
-    this.screenSize = setScreenSize();
+    this.screenSize = screenSize;
     this.state = {
       width: this.getComponentWidth(),
       marginLeft: this.getComponentOffset(),

src/components/Row.js

@@ -1,11 +1,7 @@
-/**
- * Sample React Native App
- * https://github.com/facebook/react-native
- */
 'use strict';
 
 import React from 'react-native';
-import {setScreenSize} from '../lib/ScreenSize';
+import {screenSize} from '../lib/ScreenSize';
 
 var {
   Component,
@@ -20,7 +16,7 @@ const SCREEN_WIDTH = Dimensions.get('window').width;
 export default class Row extends Component {
   constructor(props){
     super(props);
-    this.screenSize = setScreenSize();
+    this.screenSize = screenSize;
     this.state = {
       width: SCREEN_WIDTH,
       updated: false,

src/lib/ScreenSize.js

@@ -6,7 +6,7 @@ var {
   Dimensions
 } = React;
 
-export function setScreenSize(){
+function setScreenSize(){
   const SCREEN_WIDTH = Dimensions.get('window').width;
   const IPAD_WIDTH = 768;
   const IPAD_PRO_WIDTH = 1024;
@@ -21,3 +21,5 @@ export function setScreenSize(){
     return 'large';
   }
 }
+
+export const screenSize = setScreenSize();