iOS：搜索字符串未显示在搜索显示控制器的表视图上

Question

我是初学者，试图制作我的第一款应用。很抱歉，如果这是一个非常愚蠢的问题

#import "TableViewController.h"
#import "TableViewCell.h"
#import <Parse/Parse.h>

@interface TableViewController () <UISearchBarDelegate, UISearchDisplayDelegate>

@property (strong, nonatomic) IBOutlet UISearchBar *searchBar;
@property (strong, nonatomic) IBOutlet UISearchDisplayController *searchControl;
@property (nonatomic, strong) NSMutableArray *searchResults;

@end

@implementation TableViewController

- (id)initWithStyle:(UITableViewStyle)style
{
self = [super initWithStyle:style];
if (self) {
    // Custom initialization
}
return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];

    _searchControl = [[UISearchDisplayController alloc] initWithSearchBar:_searchBar     contentsController:self];
    _searchControl.searchResultsDataSource = self;
    _searchControl.searchResultsDelegate = self;
    _searchControl.delegate = self;

    self.searchResults = [NSMutableArray array];

}

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

- (void) queryForUsers:(NSString *)searchTerm {

    PFQuery * query = [PFQuery queryWithClassName:@"User"];

    [query whereKeyExists:@"username"];
    [query whereKeyExists:@"FirstName"];
    [query whereKeyExists:@"LastName"];
    [query whereKeyExists:@"CountryName"];

    [query whereKey:@"username" containsString:searchTerm];
    [query whereKey:@"FirstName" containsString:searchTerm];
    [query whereKey:@"LastName" containsString:searchTerm];

    [query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
        if (!error) {
            NSLog(@"Successful query!");
            [self.searchResults addObjectsFromArray:objects];
        }
        else {
            NSLog(@"Error in query!");
        }
    }];

}

- (BOOL) searchDisplayController:(UISearchDisplayController *)controller  shouldReloadTableForSearchString:(NSString *)searchString {

    [self queryForUsers:searchString];
    return YES;

}

#pragma mark - Table view data source

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    if (tableView == self.tableView) {
        return 0;
    }
    if (tableView == self.searchControl.searchResultsTableView) {
        return self.searchResults.count;
    }
    return 0;
}

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

    // Configure the cell...

    if (cell == nil) {
        cell = [[TableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:cellIdentifier];
    }
    else if (tableView == self.searchControl.searchResultsTableView) {
        PFObject *searchedUser = [self.searchResults objectAtIndex:indexPath.row];
        cell.userLabel.text = [searchedUser objectForKey:@"username"];
        cell.userNameLabel.text = [searchedUser objectForKey:@"FirstName" @"LastName"];
        cell.countryLabel.text = [searchedUser objectForKey:@"CountryName"];
    }

    return cell;
}

这是我的代码，我觉得我正确地调用了一切，而且一切都很好。 NSLog（@＆＃34;成功查询。＆＃34;）在我搜索时显示，但不显示任何内容。所以我不知道视图出了什么问题。任何帮助都会很棒，谢谢你提前！