for SegmentedControlIOS component,onChange(event),event.nativeEvent =null

[donghanji]

for SegmentedControlIOS component,when used onChange event,the callback param event,event.nativeEvent is null,no selectedIndex attribute.

var EventSegmentedControlExample=React.createClass({
  getInitialState(){
    return {
      values:['One','Two','Three'],
      value:'Not selected',
      selectedIndex:undefined
    };
  },
  render(){
    return(
      <View>
        <Text style={styles.text}>
          Value:{this.state.value}
        </Text>
        <Text style={styles.text}>
          Index:{this.state.selectedIndex}
        </Text>
        <SegmentedControlIOS
          values={this.state.values}
          selectedIndex={this.state.selectedIndex}
          onChange={this._onChange}
          onValueChange={this._onValueChange}
        />
      </View>
    );
  },
_onChange(event){
    console.log(event);//debug console log here
    this.setState({
      selectedIndex:event.nativeEvent.selectedIndex
    });
  },
  _onValueChange(value){
    this.setState({
      value:value
    });
  }
});

//render EventSegmentedControlExample
//

this is console log:

_dispatchIDs: null,
_dispatchListeners: null,
bubbles: nullcancelable: null,
currentTarget: null,
defaultPrevented: null,
dispatchConfig: null,
dispatchMarker: null,
eventPhase: null,
isDefaultPrevented: function () {},
isPropagationStopped: function () {},
isTrusted: null,
nativeEvent: null,//there is null
target: null,
timeStamp: null,
type: null

the SegmentedControlIOS is a new component,is this an bug?

[wwxiaofeng]

use event.nativeEvent.selectedSegmentIndex

[christopherdro]

@donghanji Did this resolve your issue?

[brentvatne]

@yangxf's answer is correct

[donghanji]

thanks everyone ^_^.sorry to being late.
change the code ,like this:

var EventSegmentedControlExample=React.createClass({
  getInitialState(){
    return {
      values:['One','Two','Three'],
      value:'Not selected',
      selectedIndex:undefined
    };
  },
  render(){
    return(
      <View>
        <Text style={styles.text}>
          Value:{this.state.value}
        </Text>
        <Text style={styles.text}>
          Index:{this.state.selectedIndex}
        </Text>
        <SegmentedControlIOS
          values={this.state.values}
          selectedIndex={this.state.selectedIndex}
          onChange={this._onChange}
          onValueChange={this._onValueChange}
        />
      </View>
    );
  },
_onChange(event){
    console.log(event.nativeEvent);//debug console log here
    this.setState({
      selectedIndex:event.nativeEvent.selectedSegmentIndex
    });
  },
  _onValueChange(value){
    this.setState({
      value:value
    });
  }
});
//

after changed ,it work well.

Whether those changes should be updated，http://facebook.github.io/react-native/docs/segmentedcontrolios.html#content

thanks everyone again.