当我想在屏幕打开时做一些动作时,我把它们放在componentDidMount中.例如,我可以获取一些数据.
像这样.
componentDidMount() {
this.updateData();
}
但是反应导航componentDidMount只在用户第一次打开屏幕时出现一次,如果以后用户再次打开此页面则不会触发componentDidMount.
使用react-navigation,您可以做到这一点.
>在componentDidMountor componentWillMount中添加侦听器
this.subs = [
this.props.navigation.addListener('didFocus',(payload) => this.componentDidFocus(payload)),];
要么
this.subs = [
this.props.navigation.addListener('didFocus',this.componentDidFocus),this.props.navigation.addListener('willBlur',this.componentWillBlur),];
然后你可以在componentDidFocus中做任何事情,比如获取数据,更新数据,……
>在componentWillUnmount中,删除侦听器
componentWillUnmount() {
this.subs.forEach(sub => sub.remove());
}
有关更多详细信息,请参阅此PR：https://github.com/react-navigation/react-navigation/pull/3345
更新：
addListener– Subscribe to updates to navigation lifecycleReact Navigation emits events to screen components that subscribe to
them:
willBlur– the screen will be unfocused
willFocus– the screen will focus
didFocus– the screen focused (if there was a transition,the
transition completed)
didBlur– the screen unfocused (if there was a transition,the
transition completed)
更新示例：
const didBlurSubscription = this.props.navigation.addListener(
'didBlur',payload => {
console.debug('didBlur',payload);
}
);
JSON有效负载：
{
action: { type: 'Navigation/COMPLETE_TRANSITION',key: 'StackRouterRoot' },context: 'id-1518521010538-2:Navigation/COMPLETE_TRANSITION_Root',lastState: undefined,state: undefined,type: 'didBlur',};
