ios - 键盘仅显示顶部并在颤动（IOS）中触摸TextField时立即隐藏

Question

class S2 extends StatefulWidget {
@override
_S2State createState() => _S2State();
}
class _S2State extends State<S2> {
 TextEditingController keyController = new TextEditingController();

我的 TextEditingController 如上

Flexible(
                            child: TextField(
                          // autofocus: true,
                          controller: keyController,
                          style: TextStyle(color: text1),
                          autocorrect: false,
                          decoration: InputDecoration(
                            enabledBorder: UnderlineInputBorder(
                                borderSide:
                                    BorderSide(color: borderUnfocused)),
                            focusedBorder: UnderlineInputBorder(
                              borderSide: BorderSide(color: borderFocused),
                            ),
                          ),
                        )),

我已经使用了上面的文本字段。

当我触摸 TextField 时我的键盘一直隐藏有什么原因？