title: How I disable the alpha, alpha numeric and special character in UITextField?
body: <p>I want to disable or also I have does not give permission entering the alpha, alpha numeric and special character in UITextField I mean when user enter the alpha and special character in text box then I want to quickly message box pop-up to showing him u only have use 0, 1-9 digit. 
  Please give me any source code and tutorials on it. </p>