Flutter常见问题汇总

欢迎加群交流（qq:839981465）

目录

1. Mac os 10.15 运行‘idevice_id’无法验证开发者
2. json数据转换
3. TextField键盘显示隐藏
4. 横竖屏设置
5. TextField光标文字焦点不对齐问题
6. ios打包白屏
7. 图片充满父视图
8. 运行报错：Unhandled Exception: ServicesBinding.defaultBinaryMessenger was accessed before the binding was initialized.
9. showModalBottomSheet顶部圆角
10. 限制TextField输入长度（使用maxLength会有counter控件）
11. 背景图会被键盘顶起
12. ios Cocoapods报错： NoMethodError - undefined method `size' for nil:NilClass
13. setState更新数据，PageView、ListView等子控件没更新

解决方案

• 1. Mac os 10.15 运行‘idevice_id’无法验证开发者

     
     
     1576138438797.jpg

sudo xattr -d com.apple.quarantine [your_path]/flutter/bin/cache/artifacts/libimobiledevice/idevice_id
sudo xattr -d com.apple.quarantine [your_path]/flutter/bin/cache/artifacts/libimobiledevice/ideviceinfo
sudo xattr -d com.apple.quarantine [your_path]/flutter/bin/cache/artifacts/libimobiledevice/idevicesyslog
sudo xattr -d com.apple.quarantine [your_path]/flutter/bin/cache/artifacts/usbmuxd/iproxy

替换为自己的路径

• 2. json数据转换
     json_to_dart

// 使用范例：
var list = json.decode(widget.itemBean.formDefaultValue);
  var items = (list as List).cast().map((value) {
  return Bean.formJson(value);
}).toList();

• 3. TextField键盘显示隐藏

// 显示键盘
focusNode.requestFocus();
// 隐藏键盘
focusNode.unfocus();

• 4. 横竖屏设置

SystemChrome.setPreferredOrientations([
    DeviceOrientation.portraitUp,
    DeviceOrientation.portraitDown
  ]);
runApp(MyApp());

• 5. TextField光标文字焦点不对齐问题

TextField(
   style: TextStyle(textBaseline: TextBaseline.alphabetic),
)

• 6. ios打包白屏

1. 在项目下终端运行：
flutter build ios --release
2. 在Xcode中打开项目， Product -> Archive 即可 

7. 图片充满父视图

ConstrainedBox(
        child: Image.asset(
                  AssetImages.start2,
                  fit: BoxFit.cover,
                  ),
        constraints: new BoxConstraints.expand(),
       )

8. 运行报错：Unhandled Exception: ServicesBinding.defaultBinaryMessenger was accessed before the binding was initialized.

void main() {
  // 加上这句即可
  WidgetsFlutterBinding.ensureInitialized();
  //
  runApp(MyApp());
}

9. showModalBottomSheet顶部圆角

    showModalBottomSheet(
      context: context,
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.circular(10),
      ),
      builder: (context) {
        return Container();
      },
    )

10. 限制TextField输入长度（使用maxLength会有counter控件）

inputFormatters: <TextInputFormatter>[
          LengthLimitingTextInputFormatter(6)
        ],

11. 背景图会被键盘顶起

Scaffold中设置：
resizeToAvoidBottomInset: false,

12. ios Cocoapods报错： NoMethodError - undefined method `size' for nil:NilClass

flutter clean
rm -Rf ios/Pods
rm -Rf ios/.symlinks
rm -Rf ios/Flutter/Flutter.framework
rm -Rf ios/Flutter/Flutter.podspec
rm -Rf ios/Podfile.lock /// 加上这个

13. setState更新数据，PageView、ListView等子控件没更新
    详见：https://www.jianshu.com/p/977e1448f95d