Flutter 如何使用intl\u phone\u number\u输入使国家/地区代码进入表单字段

我想让国家代码选择像前缀图标一样出现在

textformfield（）中。我该怎么做？。这是我从中使用的代码

InternationalPhoneNumberInput(
          onInputChanged: (PhoneNumber number) {
            print(number.phoneNumber);
          },
          onInputValidated: (bool value) {
            print(value);
          },
          selectorConfig: SelectorConfig(
            selectorType: PhoneInputSelectorType.BOTTOM_SHEET,
          ),
          ignoreBlank: false,
          autoValidateMode: AutovalidateMode.disabled,
          selectorTextStyle: TextStyle(color: Colors.black),
          initialValue: number,
          textFieldController: controller,
          formatInput: false,
          keyboardType:
              TextInputType.numberWithOptions(signed: true, decimal: true),
          inputBorder: OutlineInputBorder(),
          onSaved: (PhoneNumber number) {
            print('On Saved: $number');
          },
        ),