react native navigationOptions中不能獲取this

static navigationOptions = ({ navigation, navigationOptions,screenProps }) => {
    const { params } = navigation.state;
    return {
        tabBarVisible: true,
        headerRight:(
            <View>
                <TouchableOpacity onPress={()=>navigation.state.params.navigatePress()}>
                   //this.order()
                    <View style={{marginRight:30/1536*width}}>
                        <Text style={styles.hadlesub}>點餐</Text>
                    </View>
                </TouchableOpacity>
            </View>
        )
    }
};

// 點擊完成按鈕

order = ()=> {
    alert('haha');
}

componentDidMount() {
    // 處理數據源
    this.props.navigation.setParams({navigatePress:this.order})
}

方法二：

在最外部聲明：

let that;

在class內部：

constructor(props){ super(props); that = this; }

在const * = StackNavigation({})中：

static navigationOptions = ({ navigation, navigationOptions,screenProps }) => {
    const { params } = navigation.state;
    return {
        tabBarVisible: true,
        headerRight:(
            <View>
                <TouchableOpacity onPress={() => that.order()}>
                    <View style={{marginRight:30/1536*width}}>
                        <Text style={styles.hadlesub}>點餐</Text>
                    </View>
                </TouchableOpacity>
            </View>
        )
    }
};

order = ()=> {
    alert('haha');
}