gistfile1.m

#!/usr/bin/env objc-run

@import Foundation;

//----------------------------------------------------------------------------//
#pragma mark - interface
//----------------------------------------------------------------------------//

@interface Sample : NSObject

- (NSNumber *)identifier;

@end 

//----------------------------------------------------------------------------//
#pragma mark - implementation
//----------------------------------------------------------------------------//

@interface Sample ()
@property (copy) NSNumber *identifier;
@end 

@implementation Sample

- (instancetype)init
{
    if ((self = [super init])) {
        self.identifier = @100;
    }
    return self;
}

@end

//----------------------------------------------------------------------------//
#pragma mark - main
//----------------------------------------------------------------------------//

int main(int argc, const char *argv[])
{
    Sample *sample = [Sample new];
    NSLog(@"say: %@", sample.identifier);
    return 0;
}