从注解中获取数组索引

debugcn 发表于 Dev

小月

嗨，我想在用户点击注释时获取索引号。我有以下代码..

class ShopLocation: NSObject, MKAnnotation{

 var identifier = "Shop location"
 var title: String?
 var subtitle: String?
 var coordinate: CLLocationCoordinate2D

    init(name:String,lat:CLLocationDegrees,long:CLLocationDegrees,addInfo:String){
        title = name
        coordinate = CLLocationCoordinate2DMake(lat, long)
        subtitle = addInfo
    }

}
    class LocationList: NSObject {


        var shop = [ShopLocation]()

          override init(){
            shop += [ShopLocation(name:"t1", lat:35.673647,long:139.727686,addInfo:"info")]

            shop += [ShopLocation(name:"t2", lat:35.671928,long:139.760815,addInfo:"info")]

            shop += [ShopLocation(name:"t3", lat:35.713232,long:139.793467,addInfo:"info")]
    }

注释显示在地图上。我想获取索引，例如如果 t1 被点击，我得到的索引为 1。

我不知道写什么

func mapView(_ mapView: MKMapView, didSelect view: MKAnnotationView) {
    LocationList().shop.index(of: )

}

谢谢！

克里斯提克

我假设ShopLocation已经符合MKAnnotation，如果没有，则使其符合并将其传递给MKAnnotationView的初始值设定项。这将使其在delegate方法中可用，通过view.annotation

现在您可以访问该ShopLocation实例，我想到了两种解决方案，用于在shop

顺应Equatable-这将使firstIndex(of:)的方法Array（实际上是Collection到Array符合）

 extension ShopLocation: Equatable {
     static func ==(lhs: ShopLocation, rhs: ShopLocation) -> Bool {
         // place here the conditions for two instances to be equal
     }

 // ... later in the code

 func mapView(_ mapView: MKMapView, didSelect view: MKAnnotationView) {
     guard let shopLocation = view.annotation as? ShopLocation else {
         // this early returns if the annotation is not a shop location,
         // if you don't wan't that you can use an if-let instead
         return
     }
     let index = LocationList().shop.firstIndex(of: shopLocation)
     // do what you need with the index
 }

使用firstIndex(where:)的方法Array试（实际上的Collection:)

 func mapView(_ mapView: MKMapView, didSelect view: MKAnnotationView) {
     guard let shopLocation = view.annotation as? ShopLocation else {
         // this early returns if the annotation is not a shop location,
         // if you don't wan't that you can use an if-let instead
         return
     }
     let index = LocationList().shop.firstIndex(where: { shopLocation in
         return // same conditions as for the Equatable
     })
     // do what you need with the index
 }

就我个人而言，我建议使用方法 #1，甚至 Apple 也建议使值类型符合 Equatable。符合Equatable有助于减少代码，并启用除了index(of:)这里提到的许多其他功能。

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