Question

In the following code segment:

@implementation Foo
NSString* bar = @"Some text.";

...

@end

Is bar a static variable, or is it some kind of class or instance variable? Specifically, how is it different than doing the following:

static NSString* bar = @"Some text.";
@implementation Foo

...

@end

Answer 1

In the first example, bar is a global variable, with global linker visibility to the outside world..

In the second example, bar is a static variable, with local-file-only visibility (i.e., the symbol is not visible outside the current compilation unit).

For both examples, their positioning relative to the Objective-C keyword @implementation is irrelevant. They have absolutely nothing to do with an Objective-C class, and operate the same whether in or out of the @implementation scope.