iphone - 限制 MKMapView 滚动

Question

我正在尝试将自定义图像作为 MKOverlayView 添加到 MKMapView 中 - 我需要限制用户能够滚动到叠加层的边界之外。是否有现有的功能可以做到这一点？或者还有其他建议吗？

谢谢，马特

Answer 1

如果您只想将 map View 卡住在叠加层上，则可以将 map View 的区域设置为叠加层的边界，并将 scrollEnabled 和 zoomEnabled 设置为 否。

但这不会让用户在叠加层的边界内滚动或缩放。

没有内置方法可以将 map View 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 boundingMapRect 属性。然后可以在 regionDidChangeAnimated 委托(delegate)方法中使用它来根据需要手动调整 View 。

以下是如何完成此操作的示例。
下面的代码应该位于具有 MKMapView 的类中。
确保 map View 最初设置为叠加层可见的区域。

//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];
        }   
}

我尝试使用内置的 MKCircle 叠加层进行此操作，似乎效果很好。

<小时/>

编辑:

它确实在 95% 的情况下工作良好，但是，我通过一些测试证实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:

// 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:

- (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;
}