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iOS - MKMapView 仅显示特定缩放级别的注释

发布于 2024-10-22 02:19:56 字数 87 浏览 3 评论 0原文

我有一个带有一些自定义注释的 MKMapView，当地图缩小得很远时，这些注释看起来不太好。

是否可以仅在地图处于特定缩放级别时显示/添加它们？

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虐人心 2024-10-29 02:19:56

使用马科的回答我得出了这个解决方案。

每次区域更改时，我都会更改 ViewController 的属性 isAtBigZoom。

func mapView(mapView: MKMapView, regionDidChangeAnimated animated: Bool) {
    isAtBigZoom = mapView.region.span.latitudeDelta < 0.01
}

然后在属性的 didSet 处，我执行此代码。

var isAtBigZoom = false {
    didSet {
        // this guard ensures, that the showing and hiding happens only once
        guard oldValue != isAtBigZoom else {
            return 
        }

        // in my case I wanted to show/hide only a certain type of annotations
        for case let annot as MapTextAnnotation in mapView.annotations {
            mapView.viewForAnnotation(annot)?.alpha = isAtBigZoom ? 1 : 0
        }
    }
}

如果您还想从隐藏注释开始，只需将 alpha 更改代码添加到 viewForAnnotation 方法中即可。

效果很好，我没有注意到性能方面的大问题。尽管这可能会随着注释数量的增加而改变......

Using Marko's answer I came to this solution.

Everytime region changes, I change the ViewController's property isAtBigZoom.

func mapView(mapView: MKMapView, regionDidChangeAnimated animated: Bool) {
    isAtBigZoom = mapView.region.span.latitudeDelta < 0.01
}

Then at didSet of the property, I execute this code.

var isAtBigZoom = false {
    didSet {
        // this guard ensures, that the showing and hiding happens only once
        guard oldValue != isAtBigZoom else {
            return 
        }

        // in my case I wanted to show/hide only a certain type of annotations
        for case let annot as MapTextAnnotation in mapView.annotations {
            mapView.viewForAnnotation(annot)?.alpha = isAtBigZoom ? 1 : 0
        }
    }
}

If you also want to start with the annotations hidden, just add the alpha changing code to viewForAnnotation method.

Works great and I haven't noticed big issues with performance. Though that may change with the increasing number of annotations...

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猫性小仙女 2024-10-29 02:19:56

获取地图缩放级别

[map region];

您可以通过MKMapView 的属性。您还会收到区域更改事件的通知
通过实现 MKMapViewDelegate 方法并在此处设置委托

- (void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated

，您可以检查当前的缩放级别。我不建议在缩放/平移时删除或添加所有注释，因为这确实会影响应用程序的性能。我还没有真正尝试过将 alpha 设置为 0.0 或 MKAnnotationView 上的隐藏属性，但这可能是您最好的选择。

You can get the map zoom level via

[map region];

property of the MKMapView. also you get the notifications for region changing events
by implementing the MKMapViewDelegate method and setting the delegate

- (void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated

here you can check what your current zoom level is. I don't recommend removing or adding all the annotations while zooming / panning since that could really effect the app performance. I haven't really tried setting alpha to 0.0 or hidden property on MKAnnotationView, but that could be your best bet.

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