Sometimes when developing for iOS it’s nice to show an alert dialog that has some functionality in addition to that available from the standard UIAlertView.
This additional functionality may take the form of including a text field on an alert or showing a progress indicator on the alert dialog. Or, you may want to make the visual style of the alert match the rest of your app more closely.
A great library for assisting with these kinds of things is CODialog by Erik Aigner. The Github project page has some screenshots showing the kinds of things you can do with only a few lines of code. The library is easy to include in your project since it consists of a single header file and a single implementation file.
In addition to the out-of-the-box examples, CODialog is easy to customize in other ways as well. While I was working on Baseball Field Layout I wanted to create alert dialogs that matched the style of the app. Using CODialog and customizing the implementation slightly, I was able to get alerts that looked just the way I wanted.
This can certainly be taken too far and you should always keep the iOS Human Interface Guidelines in mind. But for adding that missing piece of functionality or adapting the display of alerts, trying something a bit different can have a big effect on your app.