string.codeUnits is an array of Unicode UTF-16 code units. So i would say it could be like
int maxLengthOfTextField(String text){
final int maxBits = 128;
List<int> unicodeSymbols = text.codeUnits.where((ch) => ch > maxBits ).toList();
return unicodeSymbols.length > 0 ? 160 : 70;
}
final textFieldController = TextEditingController();
TextField(
controller: textFieldController,
maxLength: maxLengthOfTextField(textFieldController.text)
);
修改后成为：
child: TextField(
decoration: InputDecoration(
hintStyle: TextStyle(fontSize: 17),
hintText: 'Search your trips',
// suffixIcon: Icon(Icons.search),
counterText: "",
border: InputBorder.none,
contentPadding: EdgeInsets.all(20),
),
maxLength: 480,
controller: textController,
onChanged: _onChanged,
),
_onChanged(String value) {
// print(value);
final int maxBits = 128;
List<int> unicodeSymbols = value.codeUnits.where((ch) => ch > maxBits ).toList();
if(unicodeSymbols.length > 0)
{
setState(() {
ifContainUnicode = "unicode";
});
}
else
{
setState(() {
ifContainUnicode = "bit";
});
}
setState(() {
charLength = value.length;
});
}
这个网址也可以看一下； https://dev.to/stack-labs/flutter-utf8-textfield-length-limiter-and-char-counter-31o7