Question

For an instance of myObject, is there a difference between

if (myObject == nil)

and

if (myObject)

My assumption is that if myObject hasn’t been allocated and initialized, it will be nil and the two are synonymous.

UPDATE: I’m sorry, I mis-worded my question but I think you answered what I was really asking. Let me clarify:

I have two tableViews, each with its own viewController, tblVC1 and tblVC2. For a user tap on a table row, the viewController configures a popver contentViewController, contentVC, which has tblVC1 and tblVC2 properties. So if the user tap is handled by tblVC1, it sets contentVC.tblVC1 = self, and the tblVC2 property is not initialized.

When I need to call back to the launching viewController I have been checking for which viewController to call like this:

if (tblVC1) { 
    [tlbVC1 callTheMethod]; 
} else {
    [tlbVC2 callTheMethod];
}

So I should have asked: is if (tblVC1) the same as if (tblVC1 != nil)?

Answer 1

if(myObject) checks if myObject points to an memory area != 0x0 and if(myObject == nil) checks if myObject points to 0x0.
Oh, and myObject won’t be NULL by default, but only if it is an ivar of an ObjC class, otherwise it will point to a random memory chunk.

(Disclaimer: Requesting a new memory page on iOS and Mac OS X will result in a clean memory page which means that myObject would be NULL in this case. But I wouldn’t rely on this)