title: How do i notify changes in UITextField?
body: <p>I have two text fields (one for username &amp; another is for password) and i have one button (for login). Both text fields have clearButtonMode as YES (that is i am providing the small cross x button in the right end of the text field to erase the field with an one click). </p>
  
  <p>Initially, the login button is disabled. I want to enable it if &amp; only if both text fields should have atleast one letter. Also it should work while clicking on the cross button. </p>
  
  <p>Please suggest me how to do this....</p>
  
  <p>Thanks in Advance</p>