class TimersDemo extends Component {

  constructor(props) {

      super(props);

      this.state={

        content:'',

      }

  }

  componentDidMount() {

    this.timer = setTimeout(

      () => {

        this.setState({content:'我是定时器打印的内容...One'})

      },

      500

    );

    this.timer_two = setTimeout(

      () => {

        this.setState({msg:'我是定时器打印的内容...Two'})

      },

      1000

    );

  }

  componentWillUnmount() {

    this.timer && clearTimeout(this.timer);

    this.timer_two && clearTimeout(this.timer_two);

  }

  render() {

    return (

      <View style={{margin:20}}>

        <Text style={styles.welcome}>

           定时器实例

        </Text>

        <Text>{this.state.content}</Text>

        <Text>{this.state.msg}</Text>

      </View>

    );

  }

}

<CustomButton text='测试setInterval'

   onPress={()=>{

      this.interval=setInterval(() => {this.setState({sum:(this.state.sum+1)});

   },400);

   }}

/>

<CustomButton text='clearInterval'

    onPress={()=>{

      this.interval && clearInterval(this.interval);

    }}

/>