The following code compiles:
@interface MyClass : ParentClass // missing {
// missing }
@property (nonatomic, copy) NSString *myString;
@end
I'm wondering if the curly braces in @interface declarations are actually necessary.
Asked
Active
Viewed 4,062 times
14
SundayMonday
- 19,147
- 29
- 100
- 154
-
6Did you get an error when you built with the `{`s removed? – PengOne Sep 06 '11 at 22:06
-
No compiler errors. Just seemed odd w/o the braces. – SundayMonday Sep 06 '11 at 22:09
-
No, this code will compile fine. But wait, *you said* that! – sidyll Sep 06 '11 at 22:11
-
I know :-) I was just curious because it seemed odd. – SundayMonday Sep 06 '11 at 22:29
2 Answers
22
No, the { } section isn’t necessary; your code will compile fine without it. It’s the area where you declare instance variables, and if you’re not doing that, you’re free to leave it out. You don’t even actually need to declare ivars for your properties—the compiler’s smart enough to add them where they’re needed.
Noah Witherspoon
- 57,021
- 16
- 130
- 131
-
2Depends on your compilers warning flags. You may also get an error saying the class struct has no members. – Macmade Sep 06 '11 at 22:14
-
@Mac Which warning flag? Neither clang 2.1 nor gcc 4.2.1 give warnings with `-Wall -Wextra` – Sep 06 '11 at 22:24
-
@Bavarious I get warnings in Xcode 4.1 with default settings if I omit the braces. – Beltalowda Sep 06 '11 at 22:26
-
2@Thu I don’t and I wonder why. In fact, Xcode 4.1’s template for a subclass of `NSObject` doesn’t even have braces in the class declaration. – Sep 06 '11 at 22:29
-
Maybe it is a C++-ism, it certainly is not a default behavior in Objective-C to give any such compiler warning. – bbum Sep 06 '11 at 23:14
9
The compiler is clever enough to add your @property delarations to the class.
The only use for those brackets is when you want to make a variable private, protected or specifically public.
Example:
@interface Example: NSObject {
@public
int publicVar;
@private
int privateVar;
int privateVar2;
@protected
int protectedVar;
}
@end
