shift.m

#import <Foundation/Foundation.h>


@interface NSString (Shift)
- (NSString *)shiftRight:(NSUInteger)places;
@end


@implementation NSString (Shift)

- (NSString *)shiftRight:(NSUInteger)places
{
    NSAssert(places > 0, @"places must be greater than 0");
    NSAssert(places < [self length], @"places must be less than the length of the string");

    places = [self length] - places;
    NSString *start = [self substringFromIndex:places];
    NSString *end = [self substringToIndex:places];

    return [start stringByAppendingString:end];
}

@end


int main (int argc, char const *argv[])
{
    @autoreleasepool {
        NSString *s1 = @"Soccer";
        NSString *s2 = [s1 shiftRight:2];
        NSLog(@"%@", s2);
    }
    return 0;
}