What is the benefit of sandboxing? The primary reason for sandboxing applications is security. Remember, the documentation is your friend. Even though I can be pretty sure that the array returned isn't empty, if the array were to be empty and the array would receive a message of objectAtIndex: with an argument of 0, the application would crash due to an uncaught exception.īy calling firstObject on the array, however, the array returns nil if it doesn't contain any objects, which means that no exception would be thrown. You may be wondering why I use firstObject instead of objectAtIndex: to fetch the first and only object in the array of paths. The function returns an instance of NSArray containing one result, the path to the application's Documents directory. We use the NSSearchPathForDirectoriesInDomains() function and pass the NSDocumentDirectory constant as the first argument to indicate that we're only interested in the application's Documents directory. The second and third argument are of less importance for this discussion. The application sandbox also includes controlled and limited access to user data stored on the device, system services, and hardware. In contrast to what most people think, an application's sandbox does not only refer to an application's sandbox directory in the file system. In contrast to OS X applications, an iOS application is placed in an application sandbox. Security on the iOS platform has been one of Apple's top priorities ever since the iPhone was introduced in 2007.
Did you really think you could store your application's data wherever you'd like on the file system? Think again, padawan. The data your iOS application stores can be anything from user preferences to temporary caches or even large relational datasets.īefore discussing the most common data persistence strategies developers have on the iOS platform, I'm first going to spend a few minutes discussing the file system and the concept of application sandboxing. Virtually every iOS application stores data for later use. However, there's one vital aspect of iOS development that we haven't discussed yet, data persistence. You've come a long way, grasshopper, and you've learned a lot. I will also talk about the file system on iOS and how application sandboxing affects data persistence. In this article, we'll explore the most common strategies used for storing data in an iOS application. Persisting data across application launches is a requirement that most iOS applications have, from storing user preferences using the user defaults system to managing large datasets in a relational database.
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