如何设置 CupertinoSegmentedControl 高度？

我正在尝试使用CupertinoSegmentedControl从扑动库比蒂诺图书馆 in the AppBar利用bottom属性实现如下设计（height=32）

所以我尝试了以下方法：

@override
    Widget build(BuildContext context) {
        return Scaffold(
                appBar: AppBar(
                    elevation: 2,
                    backgroundColor: Colors.white,
                    centerTitle: true,
                    title: Text(this.widget.title, style: TextStyle(color: Colors.black)),
                    bottom: PreferredSize(
        child: Padding(
          padding: const  EdgeInsets.only(top: 8, bottom: 12),
          child: Row(
            children: <Widget>[
              SizedBox(width: 24),
              Expanded(
                child: CupertinoSegmentedControl(
                  children: this.widget.tabs,
                  groupValue: this._selectedTab,
                  onValueChanged: (value) {
                    this.setState(() => this._selectedTab = value);
                    this._tabController.animateTo(value);
                  }
                ),
              ),
              SizedBox(width: 24)
            ],
          ),
        ),
        preferredSize: Size(double.infinity, 48)
      )
                ),
                body: new TabBarView(
                    controller: this._tabController,
                    children: this.widget.views,
                ));
    } 

类似的东西与您想要的布局相似吗？ （当然要去掉绿色^_^）

玩转Container and PreferredSize heights调整高度以满足您的需要。

Scaffold(
    appBar: AppBar(
        elevation: 2,
        backgroundColor: Colors.white,
        centerTitle: true,
        title:
            Text(this.widget.title, style: TextStyle(color: Colors.black)),
        bottom: PreferredSize(
            child: Row(
              children: [
                Expanded(
                  child: Container(
                    height: 48,
                    color: Colors.lightGreenAccent,
                    child: CupertinoSegmentedControl(
                        children: children,
                        groupValue: this._selectedTab,
                        onValueChanged: (value) {
                          this.setState(() => this._selectedTab = value);
                        }),
                  ),
                )
              ],
            ),
            preferredSize: Size(double.infinity, 48))),
    body: Center(
        child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Text('hello')
        ]
        )
    )
);

UPDATE:

正如 kazimad 指出的那样，如果您想增加分段控件的高度，而不仅仅是在应用栏内添加填充，您可以添加Padding小部件到您的选项卡，如下所示：

@override
Widget build(BuildContext context) {
  return Scaffold(
      appBar: AppBar(
          elevation: 2,
          backgroundColor: Colors.white,
          centerTitle: true,
          title:
              Text(this.widget.title, style: TextStyle(color: Colors.black)),
          bottom: PreferredSize(
              child: Padding(
                padding: const EdgeInsets.only(top: 8, bottom: 12),
                child: Row(
                  children: <Widget>[
                    SizedBox(width: 24),
                    Expanded(
                      child: CupertinoSegmentedControl(
                          children: const <int, Widget>{
                            0: Padding(
                                padding: EdgeInsets.all(8.0),
                                child: Text('Midnight')),
                            1: Padding(
                                padding: EdgeInsets.all(8.0),
                                child: Text('Viridian')),
                            2: Padding(
                                padding: EdgeInsets.all(8.0),
                                child: Text('Cerulean'))
                          },
                          groupValue: this._selectedTab,
                          onValueChanged: (value) {
                            // TODO: - fix it
                          }),
                    ),
                    SizedBox(width: 24)
                  ],
                ),
              ),
              preferredSize: Size(double.infinity, 48))),
      body: Center(
          child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [Text('hello')])));
}