IOS城市列表添加索引

1. 根据后端返回的城市列表，遍历模型，按照索引（A--Z）添加到字典中去：

    //MARK:- 按照城市字母顺序排序
   func getDisplayData() {
    for i in 0..<cityItems.count {
        let item = cityItems[i]
        let firstLetter = String.getFirstLetterFromString(aString: item.NAME)
        if cityDispalyData[firstLetter] != nil {
            cityDispalyData[firstLetter]?.append(item)
        }else {
            cityDispalyData[firstLetter] = [item]
            cityIndexTitles.append(firstLetter)
        }
    }
    
    //索引标题数组，按照A--Z排序
    cityIndexTitles = cityIndexTitles.sorted(by: <)
    cityIndexTitles.append("#")
    }
   

2. 实现tableView的代理和数据源方法

func numberOfSections(in tableView: UITableView) -> Int {
    return cityDispalyData.count + 1
}

func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    switch section {
    case 0:
        return 1
    default:
        return cityDispalyData[cityIndexTitles[section - 1]]?.count ?? 0
    }
}

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

    let cell: ChangeCityCell = tableView.dequeueReusableCell(for: indexPath)
    return cell

}

func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {

     let cell = cell as? ChangeCityCell
     switch indexPath.section {
        case 0:

        let cityDict = userManager.object(forKey: MainCity_Key) as? NSMutableDictionary
        let cityItem = CityListModel(dict: cityDict as! [String: AnyObject])
        cell?.reloadWithModel(model: cityItem)

        default:
            if cityDispalyData.count>0 {
            if let array = cityDispalyData[cityIndexTitles[indexPath.section - 1]] {
                let cityItem = array[indexPath.row]
                cell?.reloadWithModel(model: cityItem)
            }
        }

    }

}


func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {

    switch section {
    case 0:
        let locationTitle = UILabel()
        locationTitle.text = "  当前选择城市"
        locationTitle.font = UIFont(name: Font_Thin, size: 14)
        return locationTitle
    default:
        let locationTitle = UILabel()
        locationTitle.text = "  \(cityIndexTitles[section - 1])"
        locationTitle.font = UIFont(name: Font_Thin, size: 14)
        return locationTitle
    }

}

func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
    return cellHeight
}

func tableView(_ tableView: UITableView, heightForFooterInSection section: Int) -> CGFloat {
    return 0.0001
}

func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
    return 40
}

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    tableView.deselectRow(at: indexPath, animated: true)

    switch indexPath.section {
    case 0:

        NotificationManager.post(name: backCityArea_NoticeKey, object: nil)

    default:
        let array = cityDispalyData[cityIndexTitles[indexPath.section - 1]]
        guard let cityItem = array?[indexPath.row] else {return}
        saveCityItem(model: cityItem)

        if let block = changedCityBlock {
            block(cityItem)
        }
    }

}

func sectionIndexTitles(for tableView: UITableView) -> [String]? {
    return cityIndexTitles
}

func tableView(_ tableView: UITableView, sectionForSectionIndexTitle title: String, at index: Int) -> Int {
    return index
}

3. 根据字符串获取首字母的方法实现：

   // MARK: - 获取首字母(传入汉字字符串, 返回大写拼音首字母)
   static func getFirstLetterFromString(aString: String) -> (String) {
   let mutableString = NSMutableString.init(string: aString)
   CFStringTransform(mutableString as CFMutableString, nil, kCFStringTransformToLatin, false)
   let pinyinString = mutableString.folding(options: String.CompareOptions.diacriticInsensitive, locale: NSLocale.current)
   let strPinYin = polyphoneStringHandle(string: aString, pinyinString: pinyinString).uppercased()
   let firstString = strPinYin.substring(to: strPinYin.index(strPinYin.startIndex, offsetBy:1))
   let regexA = "^[A-Z]$"
   let predA = NSPredicate.init(format: "SELF MATCHES %@", regexA)
   return predA.evaluate(with: firstString) ? firstString : "#"
   

   }

   /// 多音字处理

   static func polyphoneStringHandle(string:String, pinyinString:String) -> String {
   if string.hasPrefix("长") {return "chang"}
   if string.hasPrefix("沈") {return "shen"}
   if string.hasPrefix("厦") {return "xia"}
   if string.hasPrefix("地") {return "di"}
   if string.hasPrefix("重") {return "chong"}
   
   return pinyinString;
   }
   

4. 总结，需要实现的方法：

   • 返回索引列表的值

      func sectionIndexTitles(for tableView: UITableView) -> [String]? {}
     

   • 组标题跟索引列表的值对应起来

     func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
     

   • 设置索引字体颜色，背景颜色，选中背景颜色

     tableView.sectionIndexColor = UIColor.black  //索引字体颜色
     tableView.sectionIndexBackgroundColor = UIColor.clear  //背景颜色
     tableView.sectionIndexTrackingBackgroundColor   //选中背景颜色