objC Preprocessor NSString Macro

Question

I have a problem to create a preprocessor macro function, that concatenates two Strings and "return" a NSString (@"...") value.

Here is what I tried:

#define ObjectKeyMake(NAME) @"com.test.##NAME"

if I print the result from a call I get:

NSLog(@"%@", ObjectKeyMake(foo)); // com.test.##NAME

so my question is: How can i concatenate 2 Strings in a preprocessor macro and "return" a NSString (@"..") ?

and no I can't use #define ObjectKeyMake(NAME) [@"com.test." stringByAppendingString: NAME] because i need a compile-time constant.

Tom Dalling · Accepted Answer · 2012-06-18 08:31:18Z

14

You can take advantage of the fact that the compiler combines string literals that are next to each other, like this:

NSString* greeting = @"Hello, " "world";

The macro implementation would look like this:

#define ObjectKeyMake(NAME) (@"com.test." #NAME)

answered Jun 18, 2012 at 8:31

Tom Dalling

24.2k7 gold badges64 silver badges81 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Vladimir · Accepted Answer · 2012-12-12 15:48:17Z

-1

#define ObjectKeyMake(NAME) @"com.test."#NAME

Vladimir

171k36 gold badges392 silver badges313 bronze badges

answered Jun 18, 2012 at 8:32

dawenhing

72 bronze badges