oc open class.

main.m

//
//  main.m
//  koans
//
//  Created by Saito on 4/13/12.
//  Copyright (c) 2012 Yava Exchange. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface NSString (RemoveSuffix)

- (NSString *)stringByRemovingSuffix:(NSString *)suffix;

@end

@implementation NSString (RemoveSuffix)

- (NSString *)stringByRemovingSuffix:(NSString *)s {
    NSString *result;
    if([self hasSuffix:s])
        result = [self substringToIndex:[self length] - [s length]];
    return result;
}

@end

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

    @autoreleasepool {
        
        NSString *hello = @"Hello World";
        NSString *x = [hello stringByRemovingSuffix:@"World"];
        NSLog(@"%@", x);
        
    }
    return 0;
}