如何将 MKAnnotation Pin 一个一个丢掉？

Posted 2023-03-14

【中文标题】如何将 MKAnnotation Pin 一个一个丢掉？

【英文标题】：How to drop MKAnnotation Pin one by one?

【发布时间】：2017-07-31 11:46:24

【问题描述】：

需要将注释一一放入地图...甚至从左到右放置注释针。有没有办法让注解drop更加时尚简洁

func addannotaiton()
    sistermaplist.mapType = MKMapType.standard
    sistermaplist.removeAnnotations(sistermaplist.annotations)
    var i = 0
    let count = mapsisterarray.count
    let span: MKCoordinateSpan = MKCoordinateSpanMake(1.5,1.5)
    while (i != count ) 

        let mbr = mapsisterarray[i]

        if mbr.lat != "",mbr.lon != ""
        let latitude  = Double((mbr.lat  ?? "0.0")!)
        let longitude = Double((mbr.lon ?? "0.0")!)

        let location: CLLocationCoordinate2D = CLLocationCoordinate2DMake(latitude!, longitude!)
        let region: MKCoordinateRegion = MKCoordinateRegionMake(location, span)
        sistermaplist.setRegion(region, animated: true)

        let annotation = MKPointAnnotation()
        annotation.coordinate = location
        annotation.title = mbr.name ?? ""

        annotation.subtitle = mbr.meet_place ?? ""

        sistermaplist.addAnnotation(annotation)



    
        i += 1
    

【问题讨论】：

删除一个 MKAnnotation pin 是什么意思？在英语中，这听起来更像是您想删除一个。然而，您的代码表明您正在添加一个。

注解通常以动画的形式拖放到地图上......这就是我所说的丢弃注解

【参考方案1】：

如果你想控制动画，我建议你自己做。您可以将MKAnnotationView 子类化并将您的引脚作为子视图添加到其中。然后将图钉设置为动画，使其随心所欲地掉落。

话虽如此，我会同时将所有注释添加到视图中，但会为运动本身设置动画。

以下是一个非常快速的示例解决方案，主要在代码中完成（地图视图和按钮位于情节提要中），因此您可以将其用作参考，但需要一些额外的工作...

import MapKit

class ViewController: UIViewController 

    @IBOutlet weak var mapView: MKMapView!


    override func viewDidLoad() 
        super.viewDidLoad()
        mapView.delegate = self
        // Do any additional setup after loading the view, typically from a nib.
    

    @IBAction func dropPinsPressed(_ sender: Any) 

        let coordinates: [CLLocationCoordinate2D] = (0..<50).map  _ in
            let point = CGPoint(x: CGFloat(Int(arc4random())%1000)/1000.0 * view.bounds.size.width, y: CGFloat(Int(arc4random())%1000)/1000.0 * view.bounds.size.height)
            return mapView.convert(point, toCoordinateFrom: mapView)
        
        let anotations = coordinates.map  Annotation(coordinate: $0) 
        let sorted = anotations.sorted  $0.coordinate.longitude < $1.coordinate.longitude 
        let duration: TimeInterval = 2.0 // overall animation duration
        let durationFragment = duration/TimeInterval(sorted.count) // Duration between 2 drops

        sorted.enumerated().forEach  $1.delay = durationFragment*TimeInterval($0) 

        mapView.addAnnotations(sorted)
    



extension ViewController: MKMapViewDelegate 

    func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? 
        return PinView(animateDropFrom: view.frame.size.height, delay: (annotation as? Annotation)?.delay ?? 0.0)
    



fileprivate extension ViewController  

    class Annotation: NSObject, MKAnnotation 
        var coordinate: CLLocationCoordinate2D
        var delay: TimeInterval = 0.0

        init(coordinate: CLLocationCoordinate2D) 
            self.coordinate = coordinate
        
    



fileprivate extension ViewController  

    class PinView: MKAnnotationView 

        lazy var pinView: UIView = 
            let view = UIView(frame: self.bounds)
            view.backgroundColor = UIColor.red
            self.addSubview(view)
            return view
        ()

        convenience init(animateDropFrom height: CGFloat, delay: TimeInterval) 
            self.init(frame: CGRect(x: 0.0, y: 0.0, width: 10.0, height: 20.0))

            pinView.frame = CGRect(x: bounds.origin.x, y: bounds.origin.y-height, width: bounds.size.width, height: bounds.size.height)

            UIView.animate(withDuration: 0.3, delay: delay, options: [.curveEaseIn], animations:  
                self.pinView.frame = self.bounds
            , completion: nil)
        

    

接下来设计最大的问题是，如果您滚动当前地图然后再返回，则被丢弃的图钉会再次掉落。由于Annotation 是自定义子类，您可能应该只将垂直偏移添加到该类中。然后，当您第一次为它设置动画时，它将偏移量重置为零，它不会再次对其进行动画处理。除非这是您的预期行为...