ios - 如何在 Google Maps ios 的中心修复标记和 GMSCircle？

Question

我想使用 swift 将标记及其圆圈固定在 map 的中心，而不管位置坐标如何。如果用户在 map 上移动相机，我希望它一直显示在中心，半径或标记没有任何闪烁，用户应该能够增加和减少圆的半径。我用过

circle.position = mapView.camera.target

但它没有帮助。所以我想知道我该怎么做？请帮助。

Answer 1

您的 ViewController 类需要从 GMSMapViewDelegate 实现 func mapView(mapView: GMSMapView!, didChangeCameraPosition position: GMSCameraPosition!) 方法。

在 func mapView(mapView: GMSMapView!, didChangeCameraPosition position: GMSCameraPosition!) 方法中，您可以更新圆圈的位置。该方法在 map 上的任何动画或手势期间重复调用(或者一次，如果相机已明确设置)。

示例代码:

class ViewController: UIViewController, GMSMapViewDelegate {

    var mapView: GMSMapView!
    var cirlce: GMSCircle!

    override func viewDidLoad() {
        super.viewDidLoad()
        let camera = GMSCameraPosition.cameraWithLatitude(-33.86,
            longitude: 151.20, zoom: 6)
        mapView = GMSMapView.mapWithFrame(CGRectZero, camera: camera)
        mapView.myLocationEnabled = true
        self.view = mapView

        mapView.delegate = self

        cirlce = GMSCircle(position: camera.target, radius: 100000)
        cirlce.fillColor = UIColor.redColor().colorWithAlphaComponent(0.5)
        cirlce.map = mapView
    }

    func mapView(mapView: GMSMapView!, didChangeCameraPosition position: GMSCameraPosition!) {
        print("\(position.target.latitude) \(position.target.longitude)")
        cirlce.position = position.target
    }

}

已编辑:

如果你想制作一个与你的 mapView 相机移动无关的圆，你可以在你的 mapView 之上制作一个圆形的 UIView。

示例代码:

class ViewController: UIViewController {

    var mapView: GMSMapView!

    override func viewDidLoad() {
        super.viewDidLoad()
        let camera = GMSCameraPosition.cameraWithLatitude(-33.86,
            longitude: 151.20, zoom: 6)
        mapView = GMSMapView.mapWithFrame(CGRectZero, camera: camera)
        mapView.myLocationEnabled = true
        self.view = mapView

        let circleView = UIView()
        circleView.backgroundColor = UIColor.redColor().colorWithAlphaComponent(0.5)
        view.addSubview(circleView)
        view.bringSubviewToFront(circleView)
        circleView.translatesAutoresizingMaskIntoConstraints = false

        let heightConstraint = NSLayoutConstraint(item: circleView, attribute: .Height, relatedBy: .Equal, toItem: nil, attribute: .NotAnAttribute, multiplier: 1, constant: 100)
        let widthConstraint = NSLayoutConstraint(item: circleView, attribute: .Width, relatedBy: .Equal, toItem: nil, attribute: .NotAnAttribute, multiplier: 1, constant: 100)
        let centerXConstraint = NSLayoutConstraint(item: circleView, attribute: .CenterX, relatedBy: .Equal, toItem: view, attribute: .CenterX, multiplier: 1, constant: 0)
        let centerYConstraint = NSLayoutConstraint(item: circleView, attribute: .CenterY, relatedBy: .Equal, toItem: view, attribute: .CenterY, multiplier: 1, constant: 0)
        NSLayoutConstraint.activateConstraints([heightConstraint, widthConstraint, centerXConstraint, centerYConstraint])

        view.updateConstraints()
        UIView.animateWithDuration(1.0, animations: {
            self.view.layoutIfNeeded()
            circleView.layer.cornerRadius = CGRectGetWidth(circleView.frame)/2
            circleView.clipsToBounds = true
        })
    }
}