Load initial text from shared prefs in TextField - flutter

Question

I'm trying to have an initial text (of my choice) at first and if the user changes it, it should save in Shared Preferences and load as initial text next time in a TextField.
Edited code a bit but it's still same, I think I'm going wrong somewhere with Shared Preferences.
String initialSignatureText = 'Sent from Mail';
TextEditingController _signatureController = TextEditingController();
String signatureText;
void convertSignature(){
String convertedSignature = _signatureController.text;
setSignature(convertedSignature);
}
void setSignature(String convertedSignature) async{
SharedPreferences signPrefs = await SharedPreferences.getInstance();
signPrefs.setString('signatureTextKey', convertedSignature);
}
Future<String> getSignature() async {
SharedPreferences signPrefs = await SharedPreferences.getInstance();
signatureText = signPrefs.get('signatureTextKey');
print(signatureText);
return signatureText;
}
#override
Widget build(BuildContext context) {
_signatureController.text = signatureText;
TextField(
maxLines: 1,
style: TextStyle(
color: Theme.of(context).textTheme.title.color,
fontSize: 18
),
controller: _signatureController,
showCursor: true,
),
FlatButton(
child: Text('Ok'),
onPressed: (){
convertSignature();
Navigator.pop(context);
},
)

Answer 1

You can assign any string to the text property of your controller
_signatureController.text = "any string";
The second way to do this would be to use TextFormField, It provides you with intialValue property.

Answer 2

I got it. I've not implemented to load initialSignatureText for first time, I'll do it later.
TextEditingController _signatureController = TextEditingController();
String initialSignatureText = 'Sent from Mail.';
var signatureText;
void convertSignature(){
String convertedSignature = _signatureController.text;
setSignature(convertedSignature);
}
void setSignature(String convertedSignature) async{
SharedPreferences signPrefs = await SharedPreferences.getInstance();
signPrefs.setString('signatureTextKey', convertedSignature);
}
Future<String> getSignature() async {
SharedPreferences signPrefs = await SharedPreferences.getInstance();
signatureText = signPrefs.get('signatureTextKey');
return signatureText;
}
void initState() {
super.initState();
getSignature();
WidgetsBinding.instance.addPostFrameCallback((_) async {
_signatureController.text = await getSignature();
});
}