I’m sure you have seen a Twitter client such as Twittelator Pro or Tweetie 2 count down the characters as you type your Tweet.  This is done by responding to the Editing Changed action on a UITextField.

 

Today, I will show you how you can implement this functionality in your application as well as show you some other real world examples of responding to this action.  Here are a few of the uses that we will discuss:

• Countdown of characters allowed – Used when the user is limited by a certain number of characters
• Word filter – useful in filtering out swear words or other unwanted text
• Live translator – our example will translate english to 1337

I will create the core code and show you how to modify it slightly to implement the other 2 applications.