react-native Button怎么不显示？

Question

<View style={{flex: 1}}>
    <TextInput
        placeholder='用户名' value={username}
        onChangeText={text => this.setState({username: text})}
        style={{height: 40, lineHeight: 40, padding: 10}}/>
    <TextInput
        secureTextEntry={true}
        onChangeText={text => this.setState({password: text})}
        value={password}
        placeholder="密码"
        style={{height: 40, lineHeight: 40, padding: 10}}/>
    <Button
        onPress={() => {
            let {username, password} = this.state;
            if (username === 'liaoyf' && password === '123') {
                navigate('Profile');
            } else {
                this.setState({
                    modalVisible: true
                })
            }
        }}
        title="登录"/>

上面的代码中，Button为什么没有高度，不显示呢？

Answer 1

包一个View, Button是根据外层容器布局的