返回时如何将数据从一个View Controller传递到Storyboard中的另一个？ [英] How to pass data from one View Controller to another in a Storyboard when going back?
问题描述
场景：
- 将UINavigationController作为初始控制器的故事板。
- MainVC（导航控制器的root） vc）需要用户在地图上选择一个位置。
- MainVC推送包含MapKit地图的VC并将其自身添加为MapVC在用户选择位置时发出的通知的侦听器。
- MapKit是一个记忆猪，我们都知道。 iOS给了我一个内存警告，我做了所有需要完成的事情，然后iOS解除分配所有可以解除分配的东西，包括MainVC。
- MapVC发出通知但是没有人去听这个。用户选择的位置丢失了，就像雨中的泪水一样。
- Storyboard with UINavigationController as initial controller.
- MainVC (navigation controller's root vc) needs the user to choose a location on a map.
- MainVC pushes a VC containing a MapKit map and adds itself as listener for a notification the MapVC sends out when the user chooses a location.
- MapKit is a memory hog, we all know that. iOS gives me a memory warning, I do all the things that need to be done, then iOS deallocates all it can deallocate, including the MainVC.
- MapVC sends out the notification but there's nobody to listen to it. The location the user chose is lost, like tears in rain.
鉴于此，什么是在去的时候传递位置数据的可靠方法回到MainVC？我甚至想把它写到〜/ tmp（这是我在处理图像等大量数据时要做的事情），但这似乎是浪费机器。是不是有一种我可以挂钩的机制，就像导航控制器返回上一个VC时触发的事件一样？比如，可以访问类似prepareForSegue的东西：但是相反的方向会很好。
Given this, what's a reliable way to pass that location data when going back to MainVC? I even thought of writing it down to ~/tmp (which is something I use to do when dealing with large amount of data like images) but that seems like a waste of machinery. Isn't there a mechanism I can hook to, like an event fired when the navigation controller goes back to the previous VC? Like, having access to something like the prepareForSegue: but on the opposite direction would be nice.
编辑我尝试去代表团但是看起来似乎我的代表仍然被释放。难道我不得不写到〜/ tmp？
EDIT I tried going for delegation but it seems my delegate gets released nonetheless. Am I stuck with having to write to ~/tmp?
推荐答案
请在此处查看我的答案，了解有关设置代表的详细说明和委托协议 - 这里
See my answer here for a detailed explanation of setting up a delegate and delegate protocol - here
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