Checking for a nil value [duplicate]

This question already has answers here: Closed 11 years ago.

Possible Duplicate:

! vs == nil in objective-c

In Objective C, is there any difference between the following two co开发者_Go百科nditionals?

NSObject *obj; if(!obj) { ... }

And:

NSObject *obj; if(obj == nil) { ... }

Thanks! Just curious, figure it's a good thing to know.

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There is no difference between the two forms.

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!obj also is valid when obj=NULL or obj=@"" or empty Array etc. You get the point.

i.e. !obj is more comprehensive since you seem to be using NSObject & not any specific object type.