[Swift通天遁地]二、表格表单-(2)创建右侧带有索引的UITableView(表单视图)

本文将演示如何给表格添加索引功能。

在项目导航区，打开视图控制器的代码文件【ViewController.swift】

现在开始编写代码，创建一个表格，并在表格右侧添加一列快捷索引。

  1 import UIKit
  2 
  3 //使当前的视图控制器类，遵循表格的数据源协议UITableViewDataSource
  4 class ViewController: UIViewController, UITableViewDataSource {
  5 
  6     //创建一个字典对象，作为表格的数据来源。字典中的键，将作为表格的索引列表。
  7     var countries :Dictionary<String, [String]> = ["A": ["Afghanistan", "Albania", "Algeria", "Angola", "Australia", "Austria", "Azerbaijan"],
  8     "B":["Bangladesh","Belgium","Bhutan","Bolivia","Brazil","Bahrain","Bulgaria"], 
  9     "C":["Canada","Congo","Chile","China","Colombia","Cuba"], 
 10     "D":["Denmark","Djibouti","Dominica"],
 11     "E":["Egypt","Estonia","Ethiopia"], 
 12     "F":["Fiji","Finland","France"], 
 13     "G":["Gambia","Germany","Greece"],
 14     "H":["Haiti","Honduras","Hungary"], 
 15     "I":["India","Indonesia","Iran","Ireland","Iraq","Italy"], 
 16     "J":["Jordan","Japan"],
 17     "K":["Kazakhstan","Korea","Kuwait"], 
 18     "L":["Laos","Libya","Lebanon"], 
 19     "M":["Madagascar","Morocco","Malaysia","Mexico","Mali","Mozambique"],
 20     "N":["Nepal","Netherlands","Nigeria","New Zealand"],
 21     "O":["Oman"], 
 22     "P":["Pakistan","Panama","Philippines","Portugal"], 
 23     "Q":["Qatar"],
 24     "R":["Romania","South Africa","Russia"],
 25     "S":["Serbia & Montenegro","Senegal","Singapore","Somalia","Switzerland"],
 26     "T":["Thailand","Turkmenistan","Tunisia","Turkey"],
 27     "U":["United Arab Emirates","United States of America","Uzbekistan"], 
 28     "V":["Vanuatu","Venezuela","Vietnam"], 
 29     "Y":["Yemen"],
 30     "Z":["Zambia","Zimbabwe"]]
 31     
 32     //创建一个字符串数组，作为当前类的另一个属性
 33     var keys:[String] = []
 34 
 35     override func viewDidLoad() {
 36         super.viewDidLoad()
 37         // Do any additional setup after loading the view, typically from a nib.
 38         
 39         //将字典的键转换为数组，并执行升序排列，这个数组将被作为索引使用
 40         keys = Array(countries.keys).sorted()
 41 
 42         //获得设备的屏幕尺寸
 43         let screenRect = UIScreen.main.bounds
 44         //创建一个矩形区域，作为表格视图的显示区域。
 45         let tableRect = CGRect(x: 0,
 46                                y: 20, 
 47                                width: screenRect.size.width, 
 48                                height: screenRect.size.height - 20)
 49         //初始化一个指定显示区域的表格对象
 50         let tableView = UITableView(frame: tableRect)
 51         
 52         //设置表格对象的数据源为当前的视图控制器对象
 53         tableView.dataSource = self
 54         //并将表格视图添加到根视图中
 55         self.view.addSubview(tableView)
 56     }
 57     
 58     //添加一个代理方法，用来设置表格的段落的数量
 59     func numberOfSections(in tableView: UITableView) -> Int
 60     {
 61         //在此设置段落的数量，等于字典中键的数量
 62         return keys.count
 63     }
 64     
 65     //添加一个代理方法，用来设置表格的行数
 66     func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int
 67     {
 68         //获得当前段落的序号，
 69         let subCountries = countries[keys[section]]
 70         //然后获得在字典中，对应的值的数量
 71         //以该数量作为当前段落的行数
 72         return (subCountries?.count)!
 73     }
 74     
 75     //添加一个代理方法，用来设置表格的段落标题
 76     func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String?
 77     {
 78         return keys[section]
 79     }
 80     
 81     //添加一个代理方法，用来设置表格索引的标题数组
 82     func sectionIndexTitles(for tableView: UITableView) -> [String]?
 83     {
 84         return keys
 85     }
 86     
 87      //添加一个代理方法，用来初始化或复用表格中的单元格
 88     func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell
 89     {
 90         //创建一个字符串常量，作为单元格的复用标识
 91         let identifier = "reusedCell"
 92         //根据复用标识，从表格中获得可以复用的单元格
 93         var cell = tableView.dequeueReusableCell(withIdentifier: identifier)
 94         
 95         //如果没有可以复用的单元格
 96         if(cell == nil)
 97         {
 98             //则初始化一个默认样式的单元格，并设置单元格的复用标识
 99             cell = UITableViewCell(style: UITableViewCellStyle.default, reuseIdentifier: identifier)
100         }
101         
102         //根据当前单元格的段落序号，获得国家名称列表
103         let subCountries = countries[keys[(indexPath as NSIndexPath).section]]
104         //根据当前单元格的序号，获得该单元格需要显示的国家名称
105         cell?.textLabel?.text = subCountries![(indexPath as NSIndexPath).row]
106         
107         //返回设置好的单元格
108         return cell!
109     }
110 
111     override func didReceiveMemoryWarning() {
112         super.didReceiveMemoryWarning()
113         // Dispose of any resources that can be recreated.
114     }
115 }