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

【问题标题】：How can I fix marker and GMSCircle on the center in Google Maps ios?如何在 Google Maps ios 的中心修复标记和 GMSCircle？
【发布时间】：2015-09-23 07:23:54
【问题描述】：

我想将标记和它的圆圈固定在地图的中心，而不考虑使用 swift 的位置坐标。如果用户在地图上移动相机，我希望它继续显示在中心而没有任何半径或标记闪烁，并且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？请帮忙。

【问题讨论】：

标签： ios swift google-maps

【解决方案1】：

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

在func mapView(mapView: GMSMapView!, didChangeCameraPosition position: GMSCameraPosition!) 方法中，您可以更新圈子的位置。该方法在地图上的任何动画或手势期间被重复调用（或一次，如果明确设置了相机）。

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：

如果您想制作一个与您的 mapView 相机移动无关的圆圈，您可以在您的 mapView 顶部制作一个圆形 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
        })
    }
}

【讨论】：

好吧，我尝试了您的代码，但圆圈与相机一起抖动，这不是我想要做的。我想让圆圈在中心静止，它不应该移动。无论如何，它都应该停留在中心而不显示任何移动过渡。 @ztan
@ztan 地图移动时如何获取圆心坐标？
@Rao 你可以用CLLocationCoordinate2D coordinate = [mapView.projection coordinateForPoint:somePoint];

【解决方案2】：

这是 Swift 3 的更新版本

import UIKit
import GoogleMaps

class ViewController: UIViewController, GMSMapViewDelegate {

var mapView: GMSMapView!

override func viewDidLoad() {
    super.viewDidLoad()
    
    let camera = GMSCameraPosition.camera(withLatitude: -33.86,
                                          longitude: 151.20, zoom: 6)
    mapView = GMSMapView.map(withFrame: .zero, camera: camera)
    mapView.isMyLocationEnabled = true
    self.view = mapView
    
    mapView.delegate = self
    
    let circleView = UIView(frame: CGRect(x: 0, y: 0, width: 20, height: 10))
    circleView.backgroundColor = UIColor.red.withAlphaComponent(0.5)
    view.addSubview(circleView)
    view.bringSubview(toFront: 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.activate([heightConstraint, widthConstraint, centerXConstraint, centerYConstraint])
    
    view.updateConstraints()
    UIView.animate(withDuration: 1.0, animations: {
        self.view.layoutIfNeeded()
        circleView.layer.cornerRadius = circleView.frame.width/2
        circleView.clipsToBounds = true
    })
    
}
func mapView(_ mapView: GMSMapView, didChange position: GMSCameraPosition) {
    print("\(position.target.latitude) \(position.target.longitude)")
     } 
}

【讨论】：