Objective-C's C# Extension Method

...is called Categories.


NSMutableArray+Selector.h:

#import <Foundation/Foundation.h>

@interface NSMutableArray (Selector)

-(NSMutableArray*) oddElements;

@end

NSMutableArray+Selector.m

#import "NSMutableArray+Selector.h"

@implementation NSMutableArray (Selector)

-(NSMutableArray *) oddElements {
    
    NSMutableArray *x = [NSMutableArray array];
    
    for(NSNumber *number in self) {
        if (number.intValue % 2 == 1) {
            [x addObject: number];
        }
    }
    
    return x;
    
}

@end

To use the categories:

#include <CoreFoundation/CoreFoundation.h>


#include "ThePerson.h"

#include "NSMutableArray+Selector.h"

void demoArray()
{
    @autoreleasepool {
        
        NSMutableArray *items = [NSMutableArray array];
        
        [items addObject: [NSNumber numberWithInteger:42]];
        
        [items addObject: [NSNumber numberWithInteger:11]];
        [items addObject: [NSNumber numberWithInteger:5]];
        [items addObject: [NSNumber numberWithInteger:1976]];
        
        
        for(NSNumber *number in [items oddElements]) {
            printf("\n%d", number.intValue);
        }
    
    }
}


int main(int argc, const char * argv[])
{
    demoArray();

    return 0;
}