ios - 搜索栏取消按钮不重新加载原始 TableView 和数据

Question

搜索和其他一切工作正常，除了当我在搜索栏上单击取消时，会出现一个空屏幕，上面有空搜索栏和原始 TableView 的导航栏。来自 Core Data 的原始、未过滤的数组不会重新加载。我已经检查了 Storyboard 中的“显示取消按钮”。我研究了许多帖子和文章，但没有任何建议奏效。控制台消息显示，在按下“取消”按钮后，在其他消息中，我看到“获取后的事件:”执行了两次。第二次(最后一次)它包含我所有的托管对象/事件，但随后“过滤数组:”为空，“事件:”为空，“events.self.count:”= 0，searchBarText 为空，self .events.count = 0.

EventViewController.h 文件:

    #import <UIKit/UIKit.h>

    #import <Foundation/Foundation.h>
    #import <CoreData/CoreData.h>

    @interface EventViewController: UITableViewController       <UISearchResultsUpdating, UISearchControllerDelegate, UITableViewDataSource, UITableViewDelegate, UISearchBarDelegate>


    {
        IBOutlet UISearchBar *searchBar;
    }

        @end

EventViewController.m 文件:

#import "EventViewController.h"
#import <CoreData/CoreData.h>
#import "EventDetailViewController.h"

@interface EventViewController ()    

@property (nonatomic, strong) NSMutableArray *events;
@property (nonatomic, strong) UISearchController *searchController;
@property(nonatomic, weak) id< UISearchResultsUpdating > searchResultsUpdater;
@property (nonatomic,strong) UISearchBar *_searchBar;
@property(nonatomic, assign) BOOL obscuresBackgroundDuringPresentation;
@property(nonatomic, weak) id< UISearchControllerDelegate > delegate;

//@property(nonatomic, assign, getter=isActive) BOOL active;

@end


@implementation EventViewController
NSMutableArray *events;


- (NSManagedObjectContext *)managedObjectContext {

    NSLog(@"Setting up managed object context");

    NSManagedObjectContext *context = nil;
    id delegate = [[UIApplication sharedApplication] delegate];
    if ([delegate performSelector:@selector(managedObjectContext)]) {
        context = [delegate managedObjectContext];
    }
    return context;

}



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

    // Fetch the events from persistent data store

    NSManagedObjectContext *managedObjectContext = [self managedObjectContext];
   NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] initWithEntityName:@"Event"];

    self.events = [[managedObjectContext executeFetchRequest:fetchRequest error:nil] mutableCopy];


      NSPredicate *resultPredicate = [NSPredicate predicateWithFormat:@"name contains[c] %@", self.searchController.searchBar.text];

   self.events = [[self.events filteredArrayUsingPredicate:resultPredicate] mutableCopy];


 }


- (BOOL)shouldReloadTableForSearchString:(UISearchController *)searchController


{


    return YES;

 }



- (void)viewDidLoad {
    [super viewDidLoad];

    self.searchController = [[UISearchController alloc] initWithSearchResultsController:nil];
    self.searchController.searchResultsUpdater = self;
    self.searchController.dimsBackgroundDuringPresentation = false;
    self.tableView.tableHeaderView = self.searchController.searchBar;
    self.definesPresentationContext = true;
    self.searchController.searchBar.delegate = self;
    self.searchController.delegate = self;
    self.searchController.obscuresBackgroundDuringPresentation = NO;

}



- (void)searchBarSearchButtonClicked:(UISearchBar *)searchBar
{

    [self.searchController.searchBar becomeFirstResponder];
}




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



- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];

    // Fetch the events from persistent data store
    NSManagedObjectContext *managedObjectContext = [self managedObjectContext];
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] initWithEntityName:@"Event"];
    self.events = [[managedObjectContext executeFetchRequest:fetchRequest error:nil] mutableCopy];

    [self.tableView reloadData];
}




- (void)searchBarCancelButtonClicked:(UISearchBar *)searchBar
{

    self.searchController.searchBar.text = nil;
    [self.searchController.searchBar resignFirstResponder];
    [self.tableView reloadData];       

    }


#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {


    return 1;
}



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


    {

        return [self.events count];
    }
}



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


    static NSString *CellIdentifier = @"Cell";
   UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];


    // Configure the cell...
    NSManagedObject *event = [self.events objectAtIndex:indexPath.row];
    [cell.textLabel setText:[NSString stringWithFormat:@"%@", [event valueForKey:@"name"]]];

        {

        event = [events objectAtIndex:indexPath.row];
        NSManagedObject *event = [self.events objectAtIndex:indexPath.row];
        [cell.textLabel setText:[NSString stringWithFormat:@"%@", [event valueForKey:@"name"]]];
    }

    return cell;

}



// Override to support conditional editing of the table view.
- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath {
    // Return NO if you do not want the specified item to be editable.
    return YES;
}



// Override to support editing the table view.

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSManagedObjectContext *context = [self managedObjectContext];

    if (editingStyle == UITableViewCellEditingStyleDelete) {
        // Delete object from database
        [context deleteObject:[self.events objectAtIndex:indexPath.row]];

        NSError *error = nil;
        if (![context save:&error]) {
            NSLog(@"Can't Delete! %@ %@", error, [error localizedDescription]);
            return;
        }

        // Remove event from table view
        [self.events removeObjectAtIndex:indexPath.row];
        [self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
    }
}


#pragma mark - Navigation


// Get the new view controller using [segue destinationViewController].
// Pass the selected object to the new view controller.

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)send


{

    if ([[segue identifier] isEqualToString:@"UpdateEvent"]) {
        NSManagedObject *selectedEvent = [self.events objectAtIndex:[[self.tableView indexPathForSelectedRow] row]];

        EventDetailViewController *destViewController = segue.destinationViewController;
        destViewController.event = selectedEvent;
    }
}

@end

Answer 1

如果你正在调用取消函数你不应该过滤数组，所以你不应该执行我下面提到的行，为此你可以检查 self.searchController.searchBar.text< 的长度 或者您可以设置一个 bool 值来检查是否单击了取消或在文本字段中输入了文本

  NSPredicate *resultPredicate = [NSPredicate predicateWithFormat:@"name contains[c] %@", self.searchController.searchBar.text];

  self.events = [[self.events filteredArrayUsingPredicate:resultPredicate] mutableCopy];