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how to remove an object only if it exists on iPhone SDK?

Answer 1

+1 A:

If by "exists" you mean "has not been deallocated," there's no way to do that. The memory where the object was may have already been replaced with a new object. However, if the object has been deallocated, it must've already been removed from its superview, because the superview will keep a reference to it.

If you're the one who is doing the releasing, then you can set lbl_timer to nil immediately after the release, so that -removeFromSuperview is sent to a nil object and does nothing. If that's not possible, you should show us some code.

John Calsbeek 2009-07-31 15:28:18

You should always, always ALWAYS set a value to nil after you are releasing it for the last time. That is mostly in dealloc - make sure you set references to nil.

Kendall Helmstetter Gelner 2009-08-04 21:09:20

Answer 2

A:

Neil Daniels 2009-08-02 06:30:36

Thanks for your reply.there was a parent view, but I wanted to know if it has already removed, it was crashing on second removal, I think. I had another global variable changing with it, I used it as a flag, cause it was urgent.I'll look in to the memory management, and the 'nil' was a new idea for me. thanks again

pMan 2009-08-03 06:47:34

Not sure if you can invoke `retainCount` for objects already deallocated, especially if the memory was reused.

notnoop 2009-08-04 03:18:20

Ah, good point. I'd have to test that out, but ya, that might cause a crash. It probably would be safer to test to make sure the object isn't nil'ed out first.

Neil Daniels 2009-08-04 04:05:24

Sending `-retainCount` to an object that has been deallocated is almost guaranteed to crash. About the only time that `-retainCount` will ever return 0 is if it was sent to a nil object.

John Calsbeek 2009-08-04 17:48:22

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