当AppState在react-native中处于非活动状态时，如何设置一些要运行的功能

Question

当AppState处于非活动状态并且我不知道该怎么办时，我尝试向数据库中的变量添加一个数字

AppState.addEventListener('change', () => this.handleAppStateChange())

handleAppStateChange(){
    if(AppState.currentState === 'inactive'){
        addIncome().then().catch(error => {})
    }
}

Answer 1

您应在add和remove中componentDidMount和componentWillUnmount AppState更改侦听器：

state = {lastAppState: AppState.currentState};

componentDidMount() {
    AppState.addEventListener('change', this.handleAppStateChange);
}

componentWillUnmount() {
    AppState.removeEventListener('change', this.handleAppStateChange);
}

另外，您还需要保存最新的AppState的状态，并在AppState更改时进行检查，以找出更改为inactive的时间：

handleAppStateChange = (nextAppState) => {
  if (
    this.state.lastAppState === 'active' &&
    nextAppState.match(/inactive|background/)
  ) {
    // your app state changes to inactive
  }

  this.setState({lastAppState: nextAppState});
};