在不同视图中调用方法的最佳方法？

Question

所以，我要直截了当。 我需要从一个视图控制器（FolderViewController）能够在另一个视图控制器（MainViewController）上调用-（void）。 我要调用的方法将根据用户选择的文件夹刷新服务器。 每当有效地选择一个文件夹之一时，我怎么称呼-（void）？

这是我的FolderViewController上的didselectPathAtIndexRow :：

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {

    MainViewController *demoController = [[MainViewController alloc] initWithNibName:@"MainViewController" bundle:nil];

    if ([[[NSUserDefaults standardUserDefaults] objectForKey:@"server"] isEqualToString:@"imap.mail.me.com"]){
        if (indexPath.row == 0)
            theAppDelegate.folder = @"INBOX";
        if (indexPath.row == 1)
            theAppDelegate.folder = @"Sent Messages";
        if (indexPath.row == 2)
            theAppDelegate.folder = @"Drafts";
        if (indexPath.row == 3)
            theAppDelegate.folder = @"Deleted Messages";
        if (indexPath.row == 4)
            theAppDelegate.folder = @"Archive";
        if (indexPath.row == 5)
            theAppDelegate.folder = @"Junk";
    } else {
        if (indexPath.row == 0)
            theAppDelegate.folder = @"INBOX";
        if (indexPath.row == 1)
            theAppDelegate.folder = @"[Gmail]/Starred";
        if (indexPath.row == 2)
            theAppDelegate.folder = @"[Gmail]/Sent Mail";
        if (indexPath.row == 3)
            theAppDelegate.folder = @"[Gmail]/Drafts";
        if (indexPath.row == 4)
            theAppDelegate.folder = @"[Gmail]/Trash";
        if (indexPath.row == 5)
            theAppDelegate.folder = @"[Gmail]/All Mail";
        if (indexPath.row == 6)
            theAppDelegate.folder = @"[Gmail]/Spam";
    }
}

这是MainViewController上的-（void）：

- (void)refreshTheServers {

    [self.menuContainerViewController toggleLeftSideMenuCompletion:^{}];

    KeychainItemWrapper* keychain = [[KeychainItemWrapper alloc] initWithIdentifier:@"KeychainTest" accessGroup:nil];

    NSString *userForConnect = [NSString stringWithFormat:@"%@", [keychain objectForKey:(__bridge id)(kSecAttrAccount)]];
    NSString *passForConnect = [NSString stringWithFormat:@"%@", [keychain objectForKey:(__bridge id)(kSecValueData)]];



    CTCoreAccount *account = [[CTCoreAccount alloc] init];

    dispatch_queue_t taskQ = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);

    dispatch_async(taskQ, ^{
        [account connectToServer:[[NSUserDefaults standardUserDefaults]
                                  stringForKey:@"server"]
                            port:993
                  connectionType:CTConnectionTypeTLS
                        authType:CTImapAuthTypePlain
                           login:userForConnect
                        password:passForConnect];

        dispatch_async(dispatch_get_main_queue(), ^{
            // ... the thread is over, do stuff on the main thread ...

            CTCoreFolder *inbox = [account folderWithPath:theAppDelegate.folder];

            NSArray *inboxMessages = [inbox messagesFromUID:1 to:0 withFetchAttributes:CTFetchAttrEnvelope];

            [[self allMessages] removeAllObjects];
            [[self allMessages] addObjectsFromArray:inboxMessages];

            [self.messagesTable reloadData];
        });
    });
}

Answer 1

通知是在不相关的类之间发出信号的好方法。 它可以传递消息，而无需在类之间创建大量依赖关系。 FolderViewController不需要对MainViewController的完全访问权限，因此您实际上并不想在它们之间放置引用。

在FolderViewController方法的末尾，输入以下内容：

[[NSNotificationCenter defaultCenter] postNotificationName:@"ChangedFolder" object:nil];

在MainViewController初始化的某个位置（例如init或viewDidLoad ），将其放置在下面：

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(refreshTheServers) name:@"ChangedFolder" object:nil];