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I have the following code :

var myBundle:NSBundle
myBundle = NSBundle.mainBundle() // what is the role of this line ??

if let path = myBundle.pathForResource("CellDescriptor", ofType: "plist"){

     var cellDescriptors: NSMutableArray! 
     cellDescriptors = NSMutableArray(contentsOfFile: path)
}

Why am I using this line of code myBundle = NSBundle.mainBundle()? I read that it is initialising myBundle object. But what does that exactly mean?

Why cannot I call pathForResource function without initialising myBundle object?

Thank you.

Doro
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Pawandeep Singh
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  • Refer to : http://stackoverflow.com/questions/3369136/what-is-nsbundle-and-mainbundle-in-objective-c – B Roopa May 31 '16 at 11:41

1 Answers1

2

Let's think about this line step by step:

myBundle = NSBundle.mainBundle()

You declared variable myBundle with type NSBundle. Now you need init this variable with proper instance object. you can use for example, constructor. But for some classes you have 'static constructor'. If you don't set variable the proper object - it have nil value by default, so you can not access instance method.

NSBundle.mainBundle()

- here is the call to mainBundle method of NSBundle class (static method) which returns you the proper instance (for this case - it's main bundle of your application. from the documentation:

The NSBundle object corresponding to the bundle directory that contains the current executable. This method may return a valid bundle object even for unbundled apps. It may also return nil if the bundle object could not be created, so always check the return value.

Hope this helps.

Doro
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  • Thank you @Doro. Can you please tell what `myBundle` will be initialised i.e what actually are we trying to initialise it ? Please bear with me as I am a beginner. – Pawandeep Singh May 31 '16 at 09:39
  • https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Classes/NSBundle_Class/ The NSBundle class has many methods for creating bundle objects, but the one you use most often is the mainBundle method. The main bundle represents the bundle directory that contains the currently executing code. So for an app, the main bundle object gives you access to the resources that shipped with your app. – Dimple Shah May 31 '16 at 11:20
  • @DShah, sure. I just explained the existent code, as in question – Doro May 31 '16 at 12:14
  • Sorry, but I have not down voted. I have just given ans to @Pawandeep Singh – Dimple Shah May 31 '16 at 12:21
  • @DShah, @Doro What I infer from your comments is that initialising `myBundle` object will give access to application main bundle. But what it means practically in coding, does it define variables,pointer of NSBundle class, without which you don't get access to locate resources ? – Pawandeep Singh Jun 01 '16 at 03:07