这些年踩过react-native的坑

1.坑之一

undefined is not an object (evaluating 'params.title')

Page2: {
    screen: Page2,
    navigationOptions: (props) => {
        const {navigation} = props;
        const {state, setParams} = navigation;
        const {params} = state; //更改这个地方
        return {
            title: params.title ? params.title : 'This is Page3',
            headerRight: (
                <Button
                    title={params.mode === 'edit' ? '保存' : '编辑'}
                    onPress={() =>
                        setParams({
                            mode: params.mode === 'edit' ? '' : 'edit'
                        })
                    }
                />
            )
        }
    }
},

改为：

const { params={} } = state;

2.坑之二

No bundle url present: when the React Packager tab is closed #14118

解决办法：
方法一：

info.plist → information Property List → + App Transport Security Settings → + Allow Arbitrary Loads = YES

方法二：

 have found the easiest/quickest way to bypass this is to exit the app within the simulator (2 x Cmd + Shift + H) and re-launch.