限制 MKMapView 滚动 [英] Restrict MKMapView scrolling

问题描述

我正在尝试将自定义图像作为 MKOverlayView 添加到 MKMapView - 我需要限制用户滚动到覆盖范围之外.是否有任何现有的功能可以做到这一点?或者有什么其他建议?

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，马特

推荐答案

如果你只是想在叠加层冻结地图视图，你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.

但这不会让用户在叠加层的边界内滚动或缩放.

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

没有内置方法可以将地图视图限制在叠加层的边界内，因此您必须手动执行此操作.首先，确保您的 MKOverlay 对象实现了 boundingMapRect 属性.然后可以在 regionDidChangeAnimated 委托方法中使用它来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.

这是如何做到这一点的示例.
下面的代码应该在具有 MKMapView 的类中.
确保地图视图最初设置为叠加层可见的区域.

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 叠加层尝试了这个，似乎效果很好.

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

它在 95% 的情况下运行良好，但是，我通过一些测试确认它可能会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，我认为这应该可以解决问题:

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;
    }
}

以防万一有人正在寻找快速的 MKOverlay 解决方案，这里有一个:

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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