import {Keyboard} from 'react-native';

state={

keyBoardHeight:0,

}

componentWillMount() {
  this.keyboardDidShowListener = Keyboard.addListener('keyboardDidShow', this._keyboardDidShow.bind(this));
  this.keyboardDidHideListener = Keyboard.addListener('keyboardDidHide', this._keyboardDidHide.bind(this));
}

componentWillUnmount() {
  this.keyboardDidShowListener.remove();
  this.keyboardDidHideListener.remove();
}

_keyboardDidShow(e) {
  this.setState({
    keyBoardHeight: e.endCoordinates.height 
  });
}

_keyboardDidHide() {
  this.setState({
    keyBoardHeight: 0
  });
}