show error about react-native-picker HOT 7 CLOSED

getInitialState :function(){
    return({
        pickerData: [{
          '北京': {
            '北京': ['朝阳区']
          }
        }],
      selectedValue: ['北京', '北京', '朝阳区']
    });
},
_onPressHandle :function(){
    this.picker.toggle();
  },
render :function(){
    return (
      <View style={{height: Dimensions.get('window').height}}>
          <TouchableOpacity style={{marginTop: 20}} onPress={this._onPressHandle}>
          <Text>点我</Text>
        </TouchableOpacity>
          <Picker
            ref={picker => this.picker = picker}
            pickerHeight={320}
            showDuration={300}
            pickerData={this.state.pickerData}
            selectedValue={this.state.selectedValue}
            onPickerDone={(pickedValue) => {
            console.log(pickedValue);
            }}/>
      </View>
 );
}