监视MKMapView重绘事件 [英] Monitor MKMapView redraw events

问题描述

当用户平移或缩放地图时，我需要根据对MKMapView的更改重绘一些UI。

I have some UI that I need to redraw based on changes to an MKMapView when the user pans or zooms the map.

目前我正在使用移动事件手势识别器和MKMapViewDelegate regionDidChangeAnimated消息重绘我的依赖UI。这是我需要的90％。

Currently I am using a move event gesture recogniser and MKMapViewDelegate regionDidChangeAnimated messages to redraw my dependant UI. This is 90% of what I need.

我缺少的事件是用户抬起手指（不再有移动事件）到MKMapViewDelegate regionDidChangeAnimated消息的时间点被解雇了。在此期间，地图缓慢停止，我的依赖用户界面停留在不同步的地图图块内容中。

The events I am missing are from the point the user lifts their finger (no more move events) to when the MKMapViewDelegate regionDidChangeAnimated message is fired. During that period the map slowly pans to a halt and my dependant UI is stuck with map tile content that is out of synch.

是否有较低级别的API会通知我重新绘制UIView（在本例中为MKMapView）内容？

Is there a lower level API that will notify me when UIView (in this case MKMapView) content is redrawn?

更新

我尝试创建一个代理MKMapView子类，它将drawRect调用转发到我提供的委托。我得到了第一个抽奖活动，但后来都没有，所以这对我的困境没有帮助。

I tried creating a proxy MKMapView subclass that forwarded drawRect calls onto my supplied delegate. I get the first draw event but none of the subsequent ones, so this doesn't help with my predicament.

推荐答案

IIRC，不幸的是，MKMapView 不符合KVO @ 区域。

IIRC, MKMapView is unfortunately not KVO-compliant for @"region".

您可能会在 regionWillChangeAnimated NSTimer c>，使用它在滚动/平移/等等过程中刷新UI，并在 regionDidChangeAnimated 中丢弃它。虽然不太优雅，如果你需要非常快，它可能不适合你的需求。

You might hack you way setting up an NSTimer in regionWillChangeAnimated, using it to refresh you UI during the scroll/pan/etc, and discarding it in regionDidChangeAnimated. Not quite elegant though, and it may not suit your needs if you need to be really fast.

或者，你可以寻找 UIScrollView 在MKMapView的子视图中，并观察其转换。

Alternatively, you may look for the UIScrollView in MKMapView's subviews, and observe its transform.

（我没有测试任何这些。）

(I haven't tested any of these.)

无论如何，我怀疑监视 MKMapView 上的重绘事件是否有用： MKMapView 使用 CATiledLayer 异步执行绘图，因此您甚至无法确定何时已经完成。

In any case, I doubt that monitoring redraw events on a MKMapView will be of any use : MKMapView uses CATiledLayer to perform its drawing asynchronously, so you can't even be sure when it's done.

编辑：这显然不适用于iOS 6.当然，这不应该真的来令人惊讶。但是，据我所知，委托方法的行为相同，因此OP的问题仍然存在。我没有找到更新的解决方案。

Edit : This apparently does not work with iOS 6. Of course, this should not really come as a surprise. However, as far as I know, the delegate methods behave the same, so the OP's problem is still real. I haven't looked for an updated solution.

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