限制MKMapView滚动 [英] Restrict MKMapView scrolling

问题描述

我正在尝试将一个自定义图像添加到一个 MKMapView 作为 MKOverlayView - 我需要限制用户能够滚动到叠加层的边界之外。有没有现有的功能来做到这一点？或任何其他建议？

I'm trying to add a custom image to an MKMapView as an MKOverlayView - I need to restrict users from being able to scroll outside the bounds of the overlay. Are there any existing functions to do this? Or any other suggestions?

谢谢，Matt

推荐答案

只需要冻结叠加层的地图视图，就可以将地图视图的区域设置为叠加层的边界，并设置 scrollEnabled 和 zoomEnabled 到 NO 。

If you just want to freeze the map view at the overlay, you could set the map view's region to the overlay's bounds and set scrollEnabled and zoomEnabled to NO.

但是这不会让用户滚动或放大叠加层的边界。

But that won't let the user scroll or zoom inside the overlay's bounds.

没有内置方法将地图视图限制在重叠式广告的边界上，因此您必须手动进行。首先，确保您的 MKOverlay 对象实现 boundingMapRect 属性。那么可以在 regionDidChangeAnimated delegate方法中使用，以便根据需要手动调整视图。

There aren't built-in ways to restrict the map view to the overlay's bounds so you'd have to do it manually. First, make sure your MKOverlay object implements the boundingMapRect property. That can then be used in the regionDidChangeAnimated delegate method to manually adjust the view as needed.

以下是一个示例如何做到这一点。

以下代码应该在具有 MKMapView 的类中。

确保地图视图最初设置为覆盖区域可见的区域。

Here's an example of how this could be done.
Code below should be in the class that has the MKMapView.
Make sure the map view is initially set to a region where the overlay is visible.

//add two ivars to the .h...
MKMapRect lastGoodMapRect;
BOOL manuallyChangingMapRect;

//in the .m...
- (void)mapView:(MKMapView *)mapView regionWillChangeAnimated:(BOOL)animated
{
    if (manuallyChangingMapRect)
        return;     
    lastGoodMapRect = mapView.visibleMapRect;
}

- (void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated
{
    if (manuallyChangingMapRect) //prevents possible infinite recursion when we call setVisibleMapRect below
        return;     

    // "theOverlay" below is a reference to your MKOverlay object.
    // It could be an ivar or obtained from mapView.overlays array.

    BOOL mapContainsOverlay = MKMapRectContainsRect(mapView.visibleMapRect, theOverlay.boundingMapRect);

    if (mapContainsOverlay)
    {
        // The overlay is entirely inside the map view but adjust if user is zoomed out too much...
        double widthRatio = theOverlay.boundingMapRect.size.width / mapView.visibleMapRect.size.width;
        double heightRatio = theOverlay.boundingMapRect.size.height / mapView.visibleMapRect.size.height;
        if ((widthRatio < 0.6) || (heightRatio < 0.6)) //adjust ratios as needed
        {
            manuallyChangingMapRect = YES;
            [mapView setVisibleMapRect:theOverlay.boundingMapRect animated:YES];
            manuallyChangingMapRect = NO;
        }
    }
    else
        if (![theOverlay intersectsMapRect:mapView.visibleMapRect])
        {
            // Overlay is no longer visible in the map view.
            // Reset to last "good" map rect...
            [mapView setVisibleMapRect:lastGoodMapRect animated:YES];
        }   
}

我用内置的 MKCircle 重叠，似乎运行良好。

I tried this with the built-in MKCircle overlay and seems to work well.

编辑：

它在95％的时间内运行良好，但是，我已经通过一些测试确认它可能在两个位置之间振荡，然后进入无限循环。所以，我编辑了一下，我认为这应该解决问题：

It does work well 95% of the time, however, I have confirmed through some testing that it might oscillate between two locations, then enter an infinite loop. So, I edited it a bit, I think this should solve the problem:

// You can safely delete this method:
- (void)mapView:(MKMapView *)mapView regionWillChangeAnimated:(BOOL)animated {

}

- (void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated {
     // prevents possible infinite recursion when we call setVisibleMapRect below
    if (manuallyChangingMapRect) {
        return;
    }

    // "theOverlay" below is a reference to your MKOverlay object.
    // It could be an ivar or obtained from mapView.overlays array.

    BOOL mapContainsOverlay = MKMapRectContainsRect(mapView.visibleMapRect, theOverlay.boundingMapRect);

    if (mapContainsOverlay) {
        // The overlay is entirely inside the map view but adjust if user is zoomed out too much...
        double widthRatio = theOverlay.boundingMapRect.size.width / mapView.visibleMapRect.size.width;
        double heightRatio = theOverlay.boundingMapRect.size.height / mapView.visibleMapRect.size.height;
        // adjust ratios as needed
        if ((widthRatio < 0.6) || (heightRatio < 0.6)) {
            manuallyChangingMapRect = YES;
            [mapView setVisibleMapRect:theOverlay.boundingMapRect animated:YES];
            manuallyChangingMapRect = NO;
        }
    } else if (![theOverlay intersectsMapRect:mapView.visibleMapRect]) {
        // Overlay is no longer visible in the map view.
        // Reset to last "good" map rect...
        manuallyChangingMapRect = YES;
        [mapView setVisibleMapRect:lastGoodMapRect animated:YES];
        manuallyChangingMapRect = NO;
    } else {
        lastGoodMapRect = mapView.visibleMapRect;
    }
}

如果有人正在寻找一个快速的 MKOverlay 解决方案，这里是一个：

And just in case someone is looking for a quick MKOverlay solution, here is one:

- (void)viewDidLoad {
    [super viewDidLoad];

    MKCircle* circleOverlay = [MKCircle circleWithMapRect:istanbulRect];
    [_mapView addOverlay:circleOverlay];

    theOverlay = circleOverlay;
}

- (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id<MKOverlay>)overlay {
    MKCircleView* circleOverlay = [[MKCircleView alloc] initWithCircle:overlay];
    [circleOverlay setStrokeColor:[UIColor mainColor]];
    [circleOverlay setLineWidth:4.f];

    return circleOverlay;
}

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