NSUserDefaults Class?

With the NSUserDefaults class, you can save settings and properties related to application or user data. For example, you could save a profile image set by the user or a default color scheme for the application. The objects will be saved in what is known as the iOS “defaults system”. The iOS defaults system is available throughout all of the code in your app, and any data saved to the defaults system will persist through application sessions. This means that even if the user closes your application or reboots their phone, the saved data will still be available the next time they open the app!

With NSUserDefaults you can save objects from the following class types:

• NSData
• NSString
• NSNumber
• NSDate
• NSArray
• NSDictionary

If you want to store any other type of object, such as a UIImage, you will typically need to archive it or wrap it in an instance of NSData, NSNumber, or NSString.

Now that you know a bit about what can be done with NSUserDefaults, let’s jump into learning how to use the defaults system with a simple sample app that will store contact information.