ipad:popover中的预测搜索

Question

我想实现这个

1)当用户开始在文本字段中键入时,popOver会闪烁,并根据在textfield中输入的字符串显示弹出窗口中表格视图中的项目列表.

2)此外,每次输入的新字母都应刷新此数据.

一种预测性搜索.

请帮助我,并提出可行的方法来实现这一点.

Answer 1

UISearchDisplayController为您完成了大部分繁重的工作.

在视图中放置一个UISearchBar(不是UITextField),并将UISearchDisplayController连接到它.

// ProductViewController.h
@property IBOutlet UISearchBar *searchBar;
@property ProductSearchController *searchController;

// ProductViewController.m
- (void) viewDidLoad
{
    [super viewDidLoad];

    searchBar.placeholder = @"Search products";
    searchBar.showsCancelButton = YES;

    self.searchController = [[[ProductSearchController alloc]
                                    initWithSearchBar:searchBar
                                    contentsController:self] autorelease];
}

我通常将UISearchDisplayController子类化,让它成为自己的委托,searchResultsDataSource和searchResultsDelegate.后两者以正常方式管理结果表.

// ProductSearchController.h
@interface ProductSearchController : UISearchDisplayController
            <UISearchDisplayDelegate, UITableViewDelegate, UITableViewDataSource>

// ProductSearchController.m
- (id)initWithSearchBar:(UISearchBar *)searchBar
                contentsController:(UIViewController *)viewController
{
    self = [super initWithSearchBar:searchBar contentsController:viewController];

    self.contents = [[NSMutableArray new] autorelease];
    self.delegate = self;
    self.searchResultsDataSource = self;
    self.searchResultsDelegate = self;

    return self;
}

搜索栏中的每个按键调用searchDisplayController:shouldReloadTableForSearchString:.快速搜索可以直接在这里实现.

- (BOOL) searchDisplayController:(UISearchDisplayController*)controller
            shouldReloadTableForSearchString:(NSString*)searchString
{
    // perform search and update self.contents (on main thread)
    return YES;
}

如果您的搜索可能需要一些时间,请在后台使用NSOperationQueue进行搜索.在我的示例中,ProductSearchOperation将showSearchResult:在何时完成调用.

// ProductSearchController.h
@property INSOperationQueue *searchQueue;

// ProductSearchController.m
- (BOOL) searchDisplayController:(UISearchDisplayController*)controller
        shouldReloadTableForSearchString:(NSString*)searchString
{
    if (!searchQueue) {
        self.searchQueue = [[NSOperationQueue new] autorelease];
        searchQueue.maxConcurrentOperationCount = 1;
    }

    [searchQueue cancelAllOperations];
    NSInvocationOperation *op = [[[ProductSearchOperation alloc]
            initWithController:self
            searchTerm:searchString] autorelease];
    [searchQueue addOperation:op];

    return NO;
}

- (void) showSearchResult:(NSMutableArray*)result
{
    self.contents = result;
    [self.searchResultsTableView
            performSelectorOnMainThread:@selector(reloadData)
            withObject:nil waitUntilDone:NO];
}