@interface ViewController ()<UITableViewDataSource, UITableViewDelegate, UISearchResultsUpdating>
@property (nonatomic, strong) NSMutableArray *dataSourceArray;
@property (nonatomic, strong) UITableView *myTableView;
@property (nonatomic, strong) UISearchController *searchController;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    [self initDataSource];
    
    self.myTableView = [[UITableView alloc] initWithFrame:self.view.bounds style:UITableViewStylePlain];
    _myTableView.delegate = self;
    _myTableView.dataSource = self;
    [self.view addSubview:_myTableView];
    
    //创建searchController
    SearchResultViewController *sResultCtrl = [[SearchResultViewController alloc] init];
    //告诉这个sCtrl 搜索之后的结果就显示在当前这个控制器上
    self.searchController = [[UISearchController alloc] initWithSearchResultsController:sResultCtrl];
    //由谁来监听searchbar上面的搜索内容发生变化的事件
    _searchController.searchResultsUpdater = self;
    //在tableView的头部显示一个searchBar
    _myTableView.tableHeaderView = _searchController.searchBar;
    //给新的界面提供一个展示的上下文
    _searchController.definesPresentationContext = YES;
}

//准备数据源
- (void)initDataSource{
    self.dataSourceArray = [NSMutableArray array];
    
    //A1 A2 A3 A4 -Z4
    for (int i = 0; i < 26; i++) {
        for (int j = 0; j < 4; j++) {
            NSString *alpha = [NSString stringWithFormat:@"%c%d",'A'+i, j+1];
            
            [_dataSourceArray addObject:alpha];
        }
    }
}

#pragma mark -- DataSource&Delegate
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView{
    return 26;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
    return 4;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
    NSString *cellID = @"CellID";
    
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellID];
    
    if (!cell) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellID];
    }
    
    cell.textLabel.text = [_dataSourceArray objectAtIndex:indexPath.section*4 + indexPath.row];
    
    return cell;
}

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section{
    return [NSString stringWithFormat:@"%c", 'A'+(int)section];
}

//索引列表的标题
- (NSArray<NSString *> *)sectionIndexTitlesForTableView:(UITableView *)tableView{
    NSMutableArray *titlesArray = [NSMutableArray array];
    
    for (int i = 0; i < 26; i++) {
        [titlesArray addObject:[NSString stringWithFormat:@"%c",'A'+i]];
    }
    return titlesArray;
}

#pragma mark --- searchResultUpdater
//监听searchBar上面内容的变化
- (void)updateSearchResultsForSearchController:(UISearchController *)searchController{
    //过滤 查找
    //定义过滤条件 只要包含搜索的内容就过滤出来
    //beginWith endWith like constains
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF contains[cd] %@", searchController.searchBar.text];
    
    //开始过滤
    NSArray *resutls = [_dataSourceArray filteredArrayUsingPredicate:predicate];
    
    //将过滤的内容显示
    SearchResultViewController *sResultCtrl = (SearchResultViewController *)_searchController.searchResultsController;
    
    sResultCtrl.dataSourceArray = resutls;
}
@end