Question

I have an NSMutableArray which can hold several objects. I would like to check if an object exists, and if so, alter it. I was wondering about checking it. I thought this would work:

if ([[[self.myLibrary objectAtIndex:1] subObject] objectAtIndex:1]) // do something

However, this will crash if there aren’t any subObjects at index 1.
So I guess the problem is that the above does not return nil if there isn’t anything at this Index.

Is there another easy way to check or will I have to count through the array etc.? I know there are other posts on stackoverflow on this, but I haven’t found a simple answer yet.

Any explanations / suggestions welcome. Thanks!

Answer 1

No check simply using :

[myArray indexOfObject:myObject];

or

[myArray containsObject:myObject];

These methods check every object using isEqual.

---

For example:

NSUInteger objIdx = [myArray indexOfObject: myObject];
if(objIdx != NSNotFound) {
    id myObj = [myArray objectAtIndex: objIdx];
    // Do some alter stuff here
}