Beginning iOS 4 Application Development

Chapter 10. File Handling

WHAT YOU WILL LEARN IN THIS CHAPTER

• Where your applications are stored on the iPhone

• The various folders within your Applications folder

• How to read and write to files in the Documents and tmp folders

• How to use a property to store structured data

• How to programmatically retrieve values stored in a property list

• How to modify the values retrieved from a property list and save the changes to a file

• How to copy bundled resources to the application's folder during runtime

All the applications you have developed up to this point are pretty straightforward — the application starts, performs something interesting, and ends. In Chapter 9, you saw how you can make use of the application settings feature to save the preferences of your application to a central location managed by the Settings application. Sometimes, however, you simply need to save some data to your application's folder for use later. For example, rather than keep files you download from a remote server in memory, a more effective and memory-efficient method is to save them in a file so that you can use them later (even after the application has shut down and restarted).

In this chapter, you learn about the two available approaches to persisting data in your application so that you can access it later: saving the data as files or a property list. You also learn how to bundle resources such as text files and database files with your application so that when the application is installed on the user's device, ...