I’m sure you have seen a Twitter client such as or 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

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

The UITextField is probably one of the most commonly used UI controls on the iPhone. It is the primary method of user input via the keyboard and provides a great deal of additional functionality.
With the success of our las API tutorial on NSArray, I thought I would do another walkthrough, this time on UITextField. I will be explaining all of the properties for it as well as bringing up some functionality that you may not have known about.
Text Attributes
The …