title: iPhone Objective-C Form Validation
body: <p>I am an old developer but new to Objective-C and iPhone development.  I am looking for the best way to do form validation for values entered.  I have been googling for a while and can't find any good code, but might be using the wrong key worrds, etc...  I am looking for things like catching for empty string, numeric validation, date validation, etc... where it catches this either while the user is entering data (input mask type) or on the lost focus of the control.</p>
  
  <p>If you can point me to some good resources that would be great!</p>
  
  <p>Thanks!</p>
  
  <p>Simon.</p>