how to set cursor position at the end of the value in flutter in textfield?

I've been having the same problem with setting a TextEditingController and this is what worked for me.

controller.text = someString;
controller.selection = TextSelection.fromPosition(TextPosition(offset: controller.text.length));

TextSelection.fromPosition() does the following (from the documentation):

Creates a collapsed selection at the given text position. A collapsed selection starts and ends at the same offset, which means it contains zero characters but instead serves as an insertion point in the text.

Edit - another version, which is a bit shorter and suggested by others here:

controller.text = someString;
controller.selection =
          TextSelection.collapsed(offset: controller.text.length);

This worked for me:

_inputCtrl.value = TextEditingValue(
  text: suggestion,
  selection: TextSelection.collapsed(offset: suggestion.length),
);

https://github.com/flutter/flutter/issues/11416#issuecomment-507040665