UITextFields firstResponder problem

hello all i am working with multiple uitextfields.i have a problem in cursor placing while changing firstResponder. i would like to do "Cursor placement in 2nd field once we entered the 3rd character in the 1st field." but the cursor stays in 3rd place.here i am restricting my first text fiel开发者_运维百科d length to 3.

This SO answer should help you. You set up notifications to be issued when the first text field state changes, firing a method that checks the text field's length. If firstTextField.text.length is equal to three characters, call [secondTextField becomeFirstResponder].