Reserved Keywords

Objective-C reserves certain words, so that you can’t, or shouldn’t, use them in your own code. At best, you’ll get a compiler warning or error; at worst, you’ll get a nasty bug that you won’t discover until millions of people are already using your app. Here is a list of reserved keywords, to help you avoid that pitfall.

Words You Can’t Use Words You Shouldn’t Use
auto BOOL
break Class
case bycopy
char byref
const id
continue IMP
default in
do inout
double nil
else NO
enum NULL
extern oneway
float out
for Protocol
goto SEL
if self
inline super
int YES
long @interface
register @end
restrict @implementation
return @protocol
short @class
signed @public
sizeof @protected
static @private
struct @property
switch @try
typedef @throw
union @catch()
unsigned @finally
void @synthesize
volatile @dynamic
while @selector
_Bool atomic
_Complex nonatomic
_Imaginery retain
Leave a comment


  1. Kenny Ray

     /  August 14, 2013

    Thanks for this list. I’m trying to find out if “name” can be used as a property name. I’m not seeing anything anywhere indicating that it is used internally like “id” is. (Found that one out the hard way).

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