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tonyarnold/gist:2010649

Created March 10, 2012 07:22
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Exhaustively check if an Objective-C object is "empty"
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gistfile1.m
static inline BOOL CBIsEmpty(id obj) {
return obj == nil
|| (NSNull *)obj == [NSNull null]
|| ([obj respondsToSelector:@selector(length)] && [obj length] == 0)
|| ([obj respondsToSelector:@selector(count)] && [obj count] == 0);
}
@nicked
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nicked commented Mar 12, 2012

For completeness, how about:

BOOL __attribute__((overloadable)) CBIsEmpty(NSNull *n) { return YES; }

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nicked commented Mar 12, 2012

Out of interest @orj, why check for nil first? Wouldn't objc_msgSend do that for you, and faster?

Also why compare to "0u", is that for performance?

Cheers

@orj
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orj commented Mar 12, 2012

Yeah, true. msgSend will indeed return 0 if the input is nil. And the 0u is just me being ultra pedantic. It is completely unnecessary.

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