prepareUrl.m

- (NSString *)prepareUrl {
    NSInteger parameterCounter = 0;
    NSString *pageUri = @"https://example.com?";
    if (query != nil) {
        query = [NSString stringWithFormat:@"query=%@", query];
        query = [self addAmpersandIfNeededForParameter:query currentParameterCounter:parameterCounter];
        pageUri = [pageUri stringByAppendingString:query];
        parameterCounter++;
    }
    if (orderBy != nil) {
        orderBy = [NSString stringWithFormat:@"orderBy=%@", orderBy];
        orderBy = [self addAmpersandIfNeededForParameter:orderBy currentParameterCounter:parameterCounter];
        pageUri = [pageUri stringByAppendingString:orderBy];
        parameterCounter++;
    }
    if (sortOrder != nil) {
        sortOrder = [NSString stringWithFormat:@"sortOrder=%@", sortOrder];
        sortOrder = [self addAmpersandIfNeededForParameter:sortOrder currentParameterCounter:parameterCounter];
        pageUri = [pageUri stringByAppendingString:sortOrder];
        parameterCounter++;
    }
    // .. and so on
    
    return pageUri;
}

- (NSString*) addAmpersandIfNeededForParameter:(NSString *)parameter currentParameterCounter:(NSInteger)currentParameterCounter {
    if (currentParameterCounter > 0) {
        NSString *ampersand = @"&";
        parameter = [ampersand stringByAppendingString:parameter];
    }
    return parameter;
}