Learn how to store data between app launchesStart Free Course
Persisting data is a necessary skill for any iOS developer. This course will teach you three techniques for storing data to your device’s hard drive: how to store small pieces of simple data using NSUserPreferences, how to save files on the device’s file system using NSFileManager, and -- most importantly -- how to manage and persist data with structure and relationships using Core Data.
This free course is your first step towards a new career with the Become an iOS Developer Nanodegree Program.
Enhance your skill set and boost your hirability through innovative, independent learning.
This course assumes intermediate iOS experience. Specifically, you have a solid foundation in Swift, including experience writing tableview-based applications. Introduction to iOS App Development with Swift and UIKit Fundamentals are good courses to take if you need to familiarize yourself with these concepts.
You will need access to a Mac computer running OS X 10.12.6 or later, and the ability to install Xcode 9.2. However, you do not need an iPad or iPhone to complete the activities. You will test and run all exercises using the iOS simulator built into Xcode.
See the Technology Requirements for using Udacity.
Apps need to be able to store information—including app settings, downloaded data, user-generated data, game state, and more—so that it isn’t lost when the app crashes or the device restarts.
The apps you’ve written up to now probably do not persist their data. They likely make use of the device’s RAM (random-access memory). RAM is volatile, meaning it only maintains its data while the device is powered. To retain data long-term, you need to save it to non-volatile memory, or storage. In the case of a desktop computer, you’d need to save it to the hard drive; in the case of iOS, we need to save it to the device’s flash memory.
Different options are available to store different types of data. In this course, you’ll learn when to use NSUserDefaults, NSFileManager, or employ Core Data, and get practice using all three.
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