进一步澄清“如何用objective c实现UISearchController”

Question

我一直在尝试通过关注stackoverflow线程来实现UISearchController：

How to implement UISearchController with objective c

和 Apples 的文档，但无法使其正常工作。当初始控制器（EVTSearchViewController 定义为UIViewController）符合UISearchBarDelegate, UISearchControllerDelegate, UISearchResultsUpdating, UITableViewDelegate （我也需要使其与UITableViewDelegate 兼容，因为我使它成为其他UITableViewController 类型EVTSearchResultsViewController *resultsControllers tableView 的代表）代表出现了，我看到我的.xib 带有UISearchBar 和@ 987654336@，我点击搜索栏开始输入：

当我输入一个字母时，搜索栏消失并且什么也没有显示：

首先，我不希望搜索栏消失。其次，updateSearchResultsForSearchController 似乎根本没有被调用，因为NSLog() 在那里设置在我在搜索栏中输入时不会产生任何输出。

我有.xib 用于EVTSearchViewController，它有一个UISearchBar，我正在连接到相应的属性：IBOutlet UISearchBar *searchBar，然后指向 UISearchControllers 的搜索栏：

self.searchBar = self.searchController.searchBar

还有UITableView，我在.xib 中放在UISearchBar 下方。我在EVTSearchViewController 中使用的另一个控制器是EVTSearchResultsViewController，它是UITableViewController，它没有.xib。

下面是viewDidLoad 和updateSearchResultsForSearchController 方法的代码：

- (void)viewDidLoad
{
_resultsController = [[EVTSearchResultsViewController alloc] init];
_searchController = [[UISearchController alloc] initWithSearchResultsController:_resultsController];

self.searchController.searchResultsUpdater = self;
self.searchController.searchBar.placeholder = nil;
[self.searchController.searchBar sizeToFit];
self.searchBar = self.searchController.searchBar;


// we want to be the delegate for our filtered table so didSelectRowAtIndexPath is called for both tables
self.resultsController.tableView.delegate = self;
self.searchController.delegate = self;
self.searchController.dimsBackgroundDuringPresentation = YES; // default is YES
self.searchController.searchBar.delegate = self; // so we can monitor text changes + others

// Search is now just presenting a view controller. As such, normal view controller
// presentation semantics apply. Namely that presentation will walk up the view controller
// hierarchy until it finds the root view controller or one that defines a presentation context.
//
self.definesPresentationContext = YES;  // know where you want UISearchController to be displayed
}

- (void)updateSearchResultsForSearchController:(UISearchController *)searchController {

// update the filtered array based on the search text
NSString *searchText = searchController.searchBar.text;
NSLog(@"searchText: %@", searchText);
if (searchText == nil) {

    // If empty the search results are the same as the original data
    self.searchResults = [[[EVTItemStore sharedStore] allItems] mutableCopy];

} else {

    NSMutableArray *searchResults = [[NSMutableArray alloc] init];

    NSArray *allEvents = [[EVTItemStore sharedStore] allItems];
    NSLog(@"allEvents: %@", allEvents);
    for (EVTItem *event in allEvents) {

        /*if ([event.number containsString:searchText] || [[phoneMO.closrr_id filteredId] containsString:searchText] || [[phoneMO.contact.fullname lowercaseString] containsString:[searchText lowercaseString]]) {
            [searchResults addObject:phoneMO];
        }*/
        if ([event.eventName containsString:searchText]) {
            [searchResults addObject:event];
        }
    }

    self.searchResults = searchResults;

}

// hand over the filtered results to our search results table
EVTSearchResultsViewController *resultsController = (EVTSearchResultsViewController *)self.searchController.searchResultsController;
resultsController.filteredEvents = self.searchResults;
[resultsController.tableView reloadData];
}

EVTSearchViewController中定义的各个@properties：

@interface EVTSearchViewController ()
@property (weak, nonatomic) IBOutlet UISearchBar *searchBar;

@property (nonatomic, strong) UISearchController *searchController;
@property (nonatomic, strong) EVTSearchResultsViewController *resultsController;
@property (nonatomic, strong) NSMutableArray *searchResults;

// For state restoration
@property BOOL searchControllerWasActive;
@property BOOL searchControllerSearchFieldWasFirstResponder;

@end

那么，这里是EVTSearchResultsViewController的代码：

#import "EVTSearchResultsViewController.h"

@implementation EVTSearchResultsViewController

- (instancetype)init
{
// Call the superclass's designated initializer
self = [super initWithStyle:UITableViewStylePlain];

if (self) {
}
return self;
}

- (void)viewDidLoad {
[super viewDidLoad];

[self.tableView registerClass:[UITableViewCell class]
       forCellReuseIdentifier:@"UISearchViewCell"];

}

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

- (NSInteger)tableView:(UITableView *)tableView
 numberOfRowsInSection:(NSInteger)section {

return [self.filteredEvents count];
}

- (UITableViewCell *)tableView:(UITableView *)tableView
     cellForRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *cell =
    [tableView dequeueReusableCellWithIdentifier:@"UISearchViewCell"
                                forIndexPath:indexPath];

cell.textLabel.text = self.filteredEvents[indexPath.row];

return cell;
}

@end

上面EVTSearchResultsViewController的方法根本没有被调用，这让我看起来很奇怪，那我们为什么需要它呢？

我尝试按照 Apple 文档推荐的方式设置 UISearchBar：

self.resultsTableView.tableHeaderView = self.searchController.searchBar;

但它给了我一个无响应的搜索框，所以当按下时没有任何反应。

有人可以帮忙解决这个问题吗？上面链接的另一个问题也可以澄清。谢谢。

Answer 1

所以，我解决了这个问题并使用UISearchController 实现了基本搜索。下面是我们实现基本搜索需要做的事情：

1. 创建两个没有.xib 文件的UITableViewControllers 类。是的，应该没有.xib 文件，我们只是创建了两个类。在下面的代码中，他们的名字是EVTSearchViewController 和EVTSearchResultsViewController。
2. 使控制器之一符合委托：<UISearchBarDelegate, UISearchControllerDelegate, UISearchResultsUpdating>

这里是EVTSearchViewController的头文件代码：

#import <UIKit/UIKit.h>

@interface EVTSearchViewController : UITableViewController <UISearchBarDelegate, UISearchControllerDelegate, UISearchResultsUpdating>

@end

这是EVTSearchResultsViewController的标题：

#import <UIKit/UIKit.h>

@interface EVTSearchResultsViewController : UITableViewController

@property (nonatomic, strong) NSMutableArray *filteredEvents;

@end

NSMutableArray *filteredEvents 将保存搜索结果。我们不应该在EVTSearchViewController.m 中实现任何UITableViewController 委托方法，而应该在EVTSearchResultsViewController.m 中实现。

这是EVTSearchViewController的上半部分：

#import "EVTSearchViewController.h"
#import "EVTSearchResultsViewController.h"

// Importing the class that stores `EVTItem` object classes
#import "EVTItemStore.h"
#import "EVTItem.h"

@interface EVTSearchViewController ()
@property (nonatomic, strong) UISearchController *searchController;
// We created this class
@property (nonatomic, strong) EVTSearchResultsViewController *resultsController;
// array to hold the results of the search
@property (nonatomic, strong) NSMutableArray *searchResults;

@end

这是EVTSearchViewController的viewDidLoad:方法的代码：

- (void)viewDidLoad
{
[super viewDidLoad];
self.resultsController = [[EVTSearchResultsViewController alloc] init];
self.searchController = [[UISearchController alloc] initWithSearchResultsController:self.resultsController];

self.searchController.searchResultsUpdater = self;
self.searchController.searchBar.placeholder = nil;
[self.searchController.searchBar sizeToFit];
// This line of code is very important. Here we are using apple docs'
// suggestion. UITableViewController has tableView property, so
// we are just setting tableView`s header to apples' UISearchController`s' `searchBar property
self.tableView.tableHeaderView = self.searchController.searchBar;

self.searchController.delegate = self;

// default is YES
self.searchController.dimsBackgroundDuringPresentation = YES;

// so we can monitor text changes + other changes
self.searchController.searchBar.delegate = self;

// know where you want UISearchController to be displayed
self.definesPresentationContext = YES;
}

然后我们给EVTSearchViewController添加如下方法：

- (void)updateSearchResultsForSearchController:(UISearchController *)searchController {

// update filtered array based on the search text
NSString *searchText = searchController.searchBar.text;
if (searchText == nil) {

    // If empty the search results should be the same as the original data
    self.searchResults = [[[EVTItemStore sharedStore] allItems] mutableCopy];

} else {

    NSMutableArray *searchResults = [[NSMutableArray alloc] init];

// [[EVTItemStore sharedStore] allItems] message retrieves
// all of the objects that I have in datastore EVTItemStore
    NSArray *allEvents = [[EVTItemStore sharedStore] allItems];

// EVTItem class has a property eventName which we are using
// for searching, then adding it to our searchResults array
    for (EVTItem *event in allEvents) {
        if ([event.eventName containsString:searchText]) {
            [searchResults addObject:event];
        }
    }

    self.searchResults = searchResults;
}

// hand over the filtered results to our search results table
EVTSearchResultsViewController *resultsController = (EVTSearchResultsViewController *)self.searchController.searchResultsController;
resultsController.filteredEvents = self.searchResults;
[resultsController.tableView reloadData];
}

另一个控制器的EVTSearchResultsViewController@implementation 部分如下所示：

@implementation EVTSearchResultsViewController

- (instancetype)init
{
// Call the superclass's designated initializer
self = [super initWithStyle:UITableViewStylePlain];

if (self) {
}
return self;
}

- (NSInteger)tableView:(UITableView *)tableView
 numberOfRowsInSection:(NSInteger)section {
return [self.filteredEvents count];
}


- (UITableViewCell *)tableView:(UITableView *)tableView
     cellForRowAtIndexPath:(NSIndexPath *)indexPath {

UITableViewCell *cell =
    [tableView dequeueReusableCellWithIdentifier:@"UISearchViewCell"
                                forIndexPath:indexPath];
EVTItem *event = self.filteredEvents[indexPath.row];
cell.textLabel.text = event.eventName;
return cell;
}

- (void)viewDidLoad
{
[super viewDidLoad];
[self.tableView registerClass:[UITableViewCell class]
                         forCellReuseIdentifier:@"UISearchViewCell"];
}

@end

就是这样。如果我们需要进一步自定义我们的单元格，我们应该能够通过将UISearchViewCell.xib 设置为EVTSearchResultsViewController 并使用以下viewDidLoad 来代替：

- (void)viewDidLoad
{
[super viewDidLoad];

// Load the NIB file
UINib *nib = [UINib nibWithNibName:@"UISearchViewCell" bundle:nil];

// Register this NIB which contains the cell
[self.tableView registerNib:nib forCellReuseIdentifier:@"UISearchViewCell"];
}