iOS 5 Programming Cookbook

1.27. Loading Data From the Main Bundle

Problem

You have added a resource (such as an image) to your Xcode project and now, at runtime, you would like to access that resource.

Solution

Use the mainBundle class method of the NSBundle class in order to retrieve your main bundle. Once that is done, use the pathForResource:ofType: method of your main bundle to retrieve the path for that specific resource. Once the path is detected, depending on the type of resource, you can either pass the path to your file to a class such as UIImage or NSData, or you can manually access the file using NSFileManager.

Note

It is required that you give a unique name to each resource inside your main bundle. For instance, it is not good practice to have a file named Default.png in more than one place inside your main bundle. Different ways of loading a resource from a bundle could then yield different results. As a result, make sure you give unique names to your files inside any bundle, regardless of whether it is the main bundle or a custom bundle that you’ve created (see Recipe 1.26).

Discussion

To access the main bundle, we can use the mainBundle class method of the NSBundle class. Bundles are all of type NSBundle and once you have an instance of a bundle, you can load resources from that bundle.

Note

Every app’s main bundle has a flat hierarchy on disk when it is compiled for submission to App Store. That means all the files that get wrapped up in your app bundle will be placed on the root folder of the main ...