在react-native中,我有这个课程(来自kitchenTricks):
import {Platform} from 'react-native';
export class UIConstants {
static AppbarHeight = Platform.OS === 'ios' ? 44 : 56;
static StatusbarHeight = Platform.OS === 'ios' ? 20 : 0;
static HeaderHeight = UIConstants.AppbarHeight + UIConstants.StatusbarHeight;
}
类的名称:AppConstants.js
问题是当我尝试导出此类时。我收到此错误:
undefined is not an object(evaluating 'UIConstants.AppbarHeight')
答案 0 :(得分:2)
在声明时不能引用同一个类。尝试更早定义高度:
const appbarHeight = Platform.OS === 'ios' ? 44 : 56;
const statusbarHeight = Platform.OS === 'ios' ? 20 : 0;
export class UIConstants {
static AppbarHeight = appbarHeight;
static StatusbarHeight = statusbarHeight;
static HeaderHeight = appbarHeight + statusbarHeight;
}
答案 1 :(得分:0)
在使用UI常量的地方,应该像导入
import {UIConstants} from './UIConstants'
不是
import UIConstants from './UIConstants'