R – release the nib’s top level objects if I don’t load the nib manually

cocoa-touchiphonememory-management

As I understand it, I do have to release the top level objects (including window, custom controller objects, …) from my Nib file, if I load it programmatically by myself.

But do I have to care about them in an simple view-based application that has only one main nib file?

And would I have to care about them when having an view-based application that uses an UITabBarController and multiple Nib files?

Best Solution

No. In all cases, the nibs are loaded once, and then unloaded when your app is closed - you don't have to manage the memory. There's no memory leak possible when you don't create more than one of a given object.

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Iphone – Referencing AppDelegate instance variables

For variables (usually the model data structure) which I need to access it anywhere in the app, declare them in your AppDelegate class. When you need to reference it:

YourAppDelegate *appDelegate = (YourAppDelegate *)[[UIApplication sharedApplication] delegate];
//and then access the variable by appDelegate.variable

R – Which are the Top Level Objects I need to create Outlests for in the File’s Owner of the Nib, so that I have less memory problems

That's correct. The File's Owner for a Nib file is the entry point into that nib. Since nothing outside your nib can refer to anything but the File's Owner, only the File's Owner can refer to other top-level items in the nib. If the File's Owner doesn't refer to them, then there is no way to release those objects when the nib is no longer needed, and they will hang around in memory.

The life cycle of a nib is something like this:

The nib is loaded and the File's Owner is associated with an object you specified.
Memory is allocated for all the top-level objects in the nib.
All the outlets are hooked up as specified in the nib.
... stuff happens ...
The File's Owner object is sent a release message.
The File's Owner releases all the objects hooked up to its outlets.

As you can see, any object that was allocated in the second step will still be floating around in memory if it wasn't released in the final step.

Best Solution

Related Solutions

Iphone – Referencing AppDelegate instance variables

R – Which are the Top Level Objects I need to create Outlests for in the File’s Owner of the Nib, so that I have less memory problems

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