重构tableview！

昨天用字典构筑tableview简直愚蠢！不过蠢过才知道如何写出好的代码。下面将用模型重构tableview！

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step1：创建一个类，封装属性，并用创建于一个类方法便于我们一次性实例化对象

#import <UIKit/UIKit.h>

@interface Province : UIViewController
//NSString一般用copy,控件一般用weak,其他用strong
@property (nonatomic,copy) NSString * header;
@property (nonatomic,copy) NSString * footer;
@property (nonatomic,strong) NSArray *cities;

+ (id) provinceWithHeader:(NSString *)header footer:(NSString *)footer cities:(NSArray *)cities;

@end

#import "Province.h"

@interface Province ()

@end

@implementation Province

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

/*
#pragma mark - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    // Get the new view controller using [segue destinationViewController].
    // Pass the selected object to the new view controller.
}
*/

+ (Province *)provinceWithHeader:(NSString *)header footer:(NSString *)footer cities:(NSArray *)cities
{
    Province * province = [[Province alloc]init];
    province.header = header;
    province.footer = footer;
    province.cities = cities;
    return province;
}

@end

step2：实例化对象创建tableview

#import "ViewController.h"
#import "Province.h"
@interface ViewController ()<UITableViewDataSource,UITableViewDelegate>
{
    NSArray * _allCities;
}
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    UITableView * tableview = [[UITableView alloc]initWithFrame:self.view.bounds style:UITableViewStyleGrouped];
    tableview.dataSource = self;
    [self.view addSubview:tableview];

    Province *gd = [Province provinceWithHeader:@"广东" footer:@"广东可以的" cities: @[@"广州",@"东莞",@"佛山"]];

    Province * zj = [Province provinceWithHeader:@"浙江" footer:@"浙江好" cities:@[@"杭州",@"台州",@"宁波",@"温州"]];

    Province * js = [Province provinceWithHeader:@"江苏" footer:@"江苏可以的" cities:@[@"南京",@"苏州",@"无锡"]];

    _allCities = @[gd,zj,js];

}
#pragma mark 一共有多少组 section==组
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{

    return _allCities.count;
}

#pragma mark 每组有多少行
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    NSArray *arr =  [_allCities[section] cities];
    return arr.count;
}

#pragma mark 为cell添加内容
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell * cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:nil];

    NSArray *arr = [_allCities[indexPath.section] cities];

    cell.textLabel.text = arr[indexPath.row];

    return cell;

}
#pragma mark 添加表头

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{

    return [_allCities[section] header];
}

#pragma mark 添加表尾
- (NSString *) tableView:(UITableView *)tableView titleForFooterInSection:(NSInteger)section
{
    return [_allCities[section] footer];
}

#pragma mark 添加索引
- (NSArray<NSString *> *)sectionIndexTitlesForTableView:(UITableView *)tableView
{
   //创建可变数组
    NSMutableArray *arr = [NSMutableArray array];
    //遍历数组里面的province对象

    for (Province * p in _allCities) {
        [arr addObject:p.header];//取出对象中的header属性
    }
    return arr;
}

@end

一下是效果图