Objective-C String Permutations

-(NSArray *)arrayWithStringPermutations:(NSString *)myString{
    NSInteger stringLength = [myString length];
    if (stringLength < 2) {
        return [NSArray arrayWithObject:myString];
    }
    else{
        NSString *head = [myString substringFromIndex:1];
        NSString *newBase = [myString substringToIndex:1];
        NSArray *permutations = [self arrayWithStringPermutations:newBase];
        NSMutableArray *permutationsArray = [NSMutableArray array];
        for (NSInteger i = 0; i<[permutations count]; i++) {
            [self mergeHeadString:head withString:newBase addTo:permutationsArray];
        }
        return permutationsArray;
    }
}
-(void)mergeHeadString:(NSString *)theString withString:(NSString *)base addTo:(NSMutableArray *)permutationsArray{
    NSUInteger count = [base length];
    while (count != 0) {
        count--;
        NSMutableString *mutBase = [base mutableCopy];
        [mutBase insertString:theString atIndex:count];
        [permutationsArray addObject:mutBase];
    }
}