iOS --- 搜索框UISearchController的使用(iOS8.0之后替代UISearchBar+display)

     

在iOS 8.0以上版本中, 咱们能够使用UISearchController来很是方便地在UITableView中添加搜索框. 而在以前版本中, 咱们仍是必须使用UISearchBar + UISearchDisplayController的组合方式.

添加UISearchController属性:

@property(strong, nonatomic) UISearchController *searchController; @property(strong, nonatomic) NSMutableArray *allCities; // 全部城市 @property(strong, nonatomic) NSMutableArray *filteredCities; // 根据searchController搜索的城市

UISearchController初始化

在viewDidLoad中初始化UISearchController:

self.searchController = [[UISearchController alloc] initWithSearchResultsController:nil]; self.searchController.searchResultsUpdater = self; self.searchController.dimsBackgroundDuringPresentation = false; [self.searchController.searchBar sizeToFit]; self.searchController.searchBar.backgroundColor = UIColorFromHex(0xdcdcdc); self.tableView.tableHeaderView = self.searchController.searchBar;

UISearchResultsUpdating协议

使用UISearchController要继承UISearchResultsUpdating协议, 实现其中的UISearchResultsUpdating方法.

#pragma mark - searchController delegate - (void)updateSearchResultsForSearchController:(UISearchController *)searchController { [self.filteredCities removeAllObjects]; NSPredicate *searchPredicate = [NSPredicate predicateWithFormat:@"SELF CONTAINS[c] %@", self.searchController.searchBar.text]; self.filteredCities = [[self.allCities filteredArrayUsingPredicate:searchPredicate] mutableCopy]; dispatch_async(dispatch_get_main_queue(), ^{ [self.tableView reloadData]; }); }

UISearchController的searchBar中的内容一旦发生变化, 就会调用该方法. 在其中, 咱们能够使用NSPredicate来设置搜索过滤的条件.

更新UITableView

引入UISearchController以后, UITableView的内容也要作相应地变更: 即cell中要呈现的内容是allCities, 仍是filteredCities. 
这一点, 能够经过UISearchController的active属性来判断, 即判断输入框是否处于active状态. 
UITableView相关的不少方法都要根据active来作判断:

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView { if (!self.searchController.active) { return self.cityKeys.count; } else { return 1; } } - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { if (!self.searchController.active) { NSString *key = self.cityKeys[section]; NSArray *citySection = self.cityDict[key]; return citySection.count; } else { return self.filteredCities.count; } } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"Cell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier]; cell.selectionStyle = UITableViewCellSelectionStyleNone; } // 根据UISearchController的active属性来判断cell中的内容 if (!self.searchController.active) { NSString *key = self.cityKeys[indexPath.section]; cell.textLabel.text = [self.cityDict[key] objectAtIndex:indexPath.row]; } else { cell.textLabel.text = self.filteredCities[indexPath.row]; } return cell; }

UISearchController的移除

在viewWillDisappear中要将UISearchController移除, 不然切换到下一个View中, 搜索框仍然会有短暂的存在.

- (void)viewWillDisappear:(BOOL)animated { [super viewWillDisappear:animated]; if (self.searchController.active) { self.searchController.active = NO; [self.searchController.searchBar removeFromSuperview]; } }