turkish phone format

NSString * formatString(NSString * input){
    // ### ### ## ##
    if ( [input length] > 8){
        return [NSString stringWithFormat:@"%@ %@",
                formatString([input substringToIndex:8]),
                [input substringFromIndex:8]];
        
    } else if ( [input length] > 6){
            return [NSString stringWithFormat:@"%@ %@",
                    formatString([input substringToIndex:6]),
                    [input substringFromIndex:6]];
        
    }else if ( [input length] > 3){
        return [NSString stringWithFormat:@"%@ %@",
                [input substringToIndex:3],
                [input substringFromIndex:3]];
        
    }else
        return input;
    
}