【Flutter 實戰】全局點擊空白處隱藏鍵盤

老孟導讀：爲何要實現點擊空白處隱藏鍵盤？由於這是 iOS 平臺的默認行爲，Android 平臺因爲其彈出的鍵盤右上角默認帶有關閉鍵盤的按鈕，因此點擊空白處不會隱藏鍵盤。git

對於單個頁面來講，經過爲 TextField 添加 focusNode，點擊空白處時使 TextField 失去焦點，實現以下：微信

class DismissKeyboardDemo extends StatelessWidget {
  final FocusNode focusNode = FocusNode();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      body: GestureDetector(
        onTap: () {
          focusNode.unfocus();
        },
        child: Container(
          color: Colors.transparent,
          alignment: Alignment.center,
          child: TextField(
            focusNode: focusNode,
          ),
        ),
      ),
    );
  }
}

當 App 中有多個頁面多個 TextField 時，此方式會增長大量重複的代碼，所以全局添加點擊空白處的監聽：app

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      builder: (context, child) => Scaffold(
        body: GestureDetector(
          onTap: () {
            FocusScopeNode currentFocus = FocusScope.of(context);
            if (!currentFocus.hasPrimaryFocus &&
                currentFocus.focusedChild != null) {
              FocusManager.instance.primaryFocus.unfocus();
            }
          },
          child: child,
        ),
      ),
      home: DismissKeyboardDemo(),
    );
  }
}

也能夠使用以下方式隱藏鍵盤：less

SystemChannels.textInput.invokeMethod('TextInput.hide');

修改 DismissKeyboardDemo 頁面：ide

class DismissKeyboardDemo extends StatelessWidget {

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      body: Center(
        child: TextField(),
      ),
    );
  }
}

效果和上面是同樣的，一樣能夠實現點擊空白處隱藏鍵盤。ui

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