constructor(props) {
    super(props);

    this.state = { email: '', password: '', error: '' };

    this.handleOnPress = this.handleOnPress.bind(this);
  }

handleOnPress() {
    const { email, password } = this.state;

    console.log(email);
  }

<Input
    value={this.state.email}
    placeholder="email@gmail.com"
    onChange={email => this.setState({ email })}
    label="Email"
  />

<TextInput
    style={styles.input}
    value={value}
    onChange={onChange}
    placeholder={placeholder}
    autoCorrect={autoCorrect}
    secureTextEntry={secureTextEntry}
  />