objective-c - why IB sometimes doesn't add a subview to a view controller

Question

Sometimes IB simply doesn't allow you to add a view as a subview to a UIViewController as illustrated here

If I drag a UIViewController from the object library and try to embed it within Mailbox View Controller.. it doesn't highlight, however it would work fine if I try to add it to the generic View Controller at the bottom (can the fact that Mailbox View Controller have a Customer Class MailboxViewController have anything to do with it?)

I'm pretty sure I can do this programmatically (which is what I'll try next) but I was wondering if there was a reason for this (and if there was a way around it).

update: this is what i'm trying to accomplish: I was following the steps here to implement a segmented view controller below search bar like in the iphone mail app.. however I kept on getting an error saying that a view can only belong to one view controller at a time.. So what I'm trying to do is basically create a separate viewcontroller, reference it from MailboxViewController as an outlet, make the containing view of my search area the view of this new view controller (this is where i'm getting stuck) and finally make the searchContentsController property of UISearchDisplayController refer to the view of this new view controller. (if this sounds confusing, which I know it does, please refer to this answer)

Answer 1

スクリーンショットから、viewメールボックス ビュー コントローラーのプロパティはテーブル ビューです。

インターフェイスビルダーのテーブルビューは、任意のビューをサブビューとしてドロップすることをサポートしていません - 実行時にそれらをどこに配置しますか? IB では、テーブルにはコンテンツがなく、セルが何であるかを示す視覚的な表現が含まれているだけです。

何を設定しようとしているのかをあなたが語っていないので、これ以上のサポートは提供できません。サブビューをプログラムでテーブル ビューに追加しても、おそらく目的の効果は得られません。テーブル ビューは UIScrollView サブクラスであるため、新しいビューは画面外に移動するか、セルを追加するテーブル ビューに隠れてしまいます。