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objective-ccoding-styleassignment-operatorcomparison-operators

In Objective C, is there a difference between if (object == nil) and if (nil == object)?

I would lean towards

if (object == nil)

but I've noticed in some tutorials the use of

if (nil == object)

Is this just a style thing, or is there some justified rationale for using either format?

Solution

  • This is typically done to prevent using an assignment operator instead of a comparison operator. If you accidently typed this for instance:

    if (object = nil)

    It may compile but it isn't what you intended.

    By using the second form you will ensure a compile time error if you mistype it, as nil cant be used as the left operand in assignments.

    Please note I'm not an objective C programmer, but this question is generic to a lot of languages.