导航栏上添加搜索栏

- (void)setupSearchBar {
    // 隐藏返回按钮
    [self.navigationItem setHidesBackButton:YES animated:YES];
    UIView *titleView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, self.view.width, 44)];
    self.searchBar = [[UISearchBar alloc] initWithFrame:CGRectMake(0, 0, self.view.width - 20, 44)];
    self.searchBar.delegate = self;

// 显示取消按钮
    self.searchBar.showsCancelButton = YES;

// 修改输入框背景色
    UITextField *searchField=[self.searchBar valueForKey:@"searchField"];
    searchField.backgroundColor = [UIColor colorWithRed:244.0/255 green:244.0/255 blue:244.0/255 alpha:1];

    self.searchBar.placeholder = NSLocalizedString(@"搜索测试题", nil);
    [titleView addSubview:self.searchBar];
    self.navigationItem.titleView = titleView;
    
}