在 MKMapview 上移动 MKCircle 并拖动 MKMapview

Question

我在 MKMapView 上有一个 MKCircle。它是用户可拖动的，但如果用户将区域拖动到圆圈外，则地图应该会移动。

- (IBAction)createPanGestureRecognizer:(id)sender
{
    _mapView.scrollEnabled=NO;
    _panRecognizer = [[UIPanGestureRecognizer alloc]
                      initWithTarget:self action:@selector(respondToPanGesture:)];
    [_mapView addGestureRecognizer:_panRecognizer];
}

-(void)respondToPanGesture:(UIPanGestureRecognizer*)sender {

    static CGPoint originalPoint;

    if (sender.state == UIGestureRecognizerStateBegan) {
        CGPoint point = [sender locationInView:_mapView];
        CLLocationCoordinate2D tapCoordinate = [_mapView convertPoint:point toCoordinateFromView:_mapView];

        CLLocation *tapLocation = [[CLLocation alloc] initWithLatitude:tapCoordinate.latitude longitude:tapCoordinate.longitude];

        CLLocationCoordinate2D originalCoordinate = [_circle coordinate];
        CLLocation *originalLocation = [[CLLocation alloc] initWithLatitude:originalCoordinate.latitude longitude:originalCoordinate.longitude];

        if ([tapLocation distanceFromLocation:originalLocation] > [_circle radius]) {
            _mapView.scrollEnabled=YES;
            _isAllowedToMove=NO;
        }
        else if ([tapLocation distanceFromLocation:originalLocation] < [_circle radius]) {
            originalPoint = [_mapView convertCoordinate:originalCoordinate toPointToView:sender.view];
            _isAllowedToMove=YES;
        }
    }

    if (sender.state == UIGestureRecognizerStateChanged) {
        if (_isAllowedToMove)
        {
            CGPoint translation = [sender translationInView:sender.view];
            CGPoint newPoint    = CGPointMake(originalPoint.x + translation.x, originalPoint.y + translation.y);

            CLLocationCoordinate2D newCoordinate = [_mapView convertPoint:newPoint toCoordinateFromView:sender.view];

            MKCircle *circle2 = [MKCircle circleWithCenterCoordinate:newCoordinate radius:[_circle radius]];
            [_mapView addOverlay:circle2];
            [_mapView removeOverlay:_circle];
            _circle = circle2;
        }
    }

    if (sender.state == UIGestureRecognizerStateEnded || sender.state == UIGestureRecognizerStateFailed || sender.state == UIGestureRecognizerStateCancelled) {
        _mapView.scrollEnabled=NO;
        _isAllowedToMove=NO;
    }
}

拖动圆圈可以正常工作，但在尝试拖动地图时，它会保持静止。 我的假设是

_mapView.scrollEnabled=YES;

使地图可拖动，但需要启动另一个拖动手势。 如何在不失去移动圆圈的能力的情况下做到这一点？

Answer 1

使地图可以在用户开始拖到圆圈外时被拖动（并且不如果用户开始在圆圈内拖动 )，不要从一开始就禁用scrollEnabled——让它保持打开状态（直到拖动开始我们可以决定是否禁用）。

为了在初始状态下保持scrollEnabled（即让地图自己平移）和添加我们自己的手势识别器，我们需要实现shouldRecognizeSimultaneouslyWithGestureRecognizer并返回@ 987654324@.

更新后的createPanGestureRecognizer: 如下所示：

- (IBAction)createPanGestureRecognizer:(id)sender
{
    //_mapView.scrollEnabled=NO;  // <-- do NOT disable scrolling here
    _panRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(respondToPanGesture:)];
    _panRecognizer.delegate = self;  // <-- to implement shouldRecognize
    [_mapView addGestureRecognizer:_panRecognizer];
}

-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
    return YES;
}

然后在我们的手势处理程序中，当手势开始时，根据平移开始的位置（圆圈外或圆圈内）启用或禁用scrollEnabled：

if ([tapLocation distanceFromLocation:originalLocation] > [_circle radius]) {
    _mapView.scrollEnabled=YES;
    _isAllowedToMove=NO;
}
else //if ([tapLocation distanceFromLocation:originalLocation] < [_circle radius]) {
//NOTE: It's not really necessary to check if distance is less than radius
//      in the ELSE part since in the IF we checked if it's greater-than.
//      If we get to the ELSE, we know distance is <= radius.
//      Unless for some reason you want to handle the case where
//      distance exactly equals radius differently but this is unlikely.
{
    originalPoint = [_mapView convertCoordinate:originalCoordinate toPointToView:sender.view];
    _mapView.scrollEnabled=NO;  // <-- disable scrolling HERE
    _isAllowedToMove=YES;
}

最后，在手势结束时始终重新启用scrollEnabled（以防万一）。
当下一个手势开始时，必要时会重新禁用：

if (sender.state == UIGestureRecognizerStateEnded || sender.state == UIGestureRecognizerStateFailed || sender.state == UIGestureRecognizerStateCancelled) {
    _mapView.scrollEnabled=YES;  // <-- enable instead of disable
    _isAllowedToMove=NO;
}

请注意，如果允许用户多次调用createPanGestureRecognizer:，您可能应该将识别器的创建和添加移到其他地方（可能是viewDidLoad），否则会向地图添加多个实例。

或者，将按钮更改为切换按钮，这样如果“移动”模式开启，它会从地图中移除手势识别器，而不是创建和添加它。

Answer 2

使用 swift 4

更新了答案

包括一些变化： panGesture.maximumNumberOfTouches = 1 避免将捏合缩放为平移手势 用于可以启动平移手势的活动区域的屏幕点。

private func addPanGestureRecognizer(to map: MKMapView) {
    let panGesture = UIPanGestureRecognizer(target: self, action: #selector(respondToPanGesture(_:)))
    panGesture.maximumNumberOfTouches = 1
    panGesture.delegate = self
    map.addGestureRecognizer(panGesture)
}

@objc private func respondToPanGesture(_ sender: UIPanGestureRecognizer) {
    guard let map = self.map else {
        return
    }

    let circlePoint = map.convert(startPoint, toPointTo: map) // circle center in View coordinate system

    switch sender.state {
    case .began:
        let point = sender.location(in: map)
        // Set touch radius in points (20), not meters to support different map zoom levels
        if point.radiusContainsPoint(radius: 20, point: circlePoint) {
            // set class property to store initial circle position before start dragging
            initialDragPoint = circlePoint
            map.isScrollEnabled = false
            isDragEnabled = true
        }
        else {
            map.isScrollEnabled = true
            isDragEnabled = false
        }
    case .changed:
        if isDragEnabled {
            let translation = sender.translation(in: map)
            let newPoint = CGPoint(x: initialDragPoint.x + translation.x, y: initialDragPoint.y + translation.y)
            let updatedCoordinate = map.convert(newPoint, toCoordinateFrom: map)
            let newOverlay = makeCircleOverlay(at: updatedCoordinate)
            map.remove(circleOverlay)
            map.add(newOverlay)
            circleOverlay = newOverlay
        }
    case .ended, .failed, .cancelled:
        map.isScrollEnabled = true
        isDragEnabled = false
    case .possible:
        break
    }
}

// MARK: - UIGestureRecognizerDelegate
func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
    return true
}