#react-native-textinput ##Platform ios、android ##example
<Input
autoFocus={true}
keyboardType={'numeric'}
maxLength={4}
placeholder={'请输入你的邀请码'}
onChangeText={(text) => this.setState({invitationCode: text})}
_onDelTextHandle={() => this.setState({invitationCode: ''})}
value={this.state.invitationCode}
/>