我在修改線程內的視圖時遇到問題。我試圖添加一個子視圖，但是顯示大約需要6秒鐘或更長時間。我終于使它工作了，但我不知道它到底是怎么做到的。所以我想知道為什么它起作用以及以下方法之間的區別是什么：//this worked -added the view instantlydispatch_async(dispatch_get_main_queue(), ^{    //some UI methods ej    [view addSubview: otherView];}//this took around 6 or more seconds to display[viewController performSelectorOnMainThread:@selector(methodThatAddsSubview:) withObject:otherView waitUntilDone:NO];//Also didnt work: NSNotification methods -  took also around 6 seconds to display//the observer was in the viewController I wanted to modify//paired to a method to add a subview.[[NSNotificationCenter defaultCenter] postNotificationName: @"notification-identifier" object:object];作為參考，在ACAccountStore類的完成處理程序內部調用了該方法。accountStore requestAccessToAccountsWithType:accountType withCompletionHandler:^(BOOL granted, NSError *error) {            if(granted) {            //my methods were here            }}編輯：當我說它不起作用時，我的意思是花了大約6秒鐘才能顯示我添加的視圖。