Question

以下代码是关于堆栈溢出的相同问题。然而，看起来代码是在swift 2中。我为一些代码添加了一个图像jj，但我收到1条错误消息。错误消息为var anView = thisMAP.dequeueReusableAnnotationView(withIdentifier: reuseId )。错误消息指出 reuseId是未解析的标识符这是唯一的错误消息。如果修复了，代码将编译。

import UIKit
import MapKit

class Annotation: NSObject, MKAnnotation
{
var coordinate: CLLocationCoordinate2D = CLLocationCoordinate2D(latitude: 0.0, longitude: 0.0)
var custom_image: Bool = true
var color: MKPinAnnotationColor = MKPinAnnotationColor.purple
}
class ViewController: UIViewController, MKMapViewDelegate {
@IBOutlet var thisMAP: MKMapView!

override func viewDidLoad() {
    super.viewDidLoad()

    self.thisMAP.delegate = self;

    let annotation = Annotation()
    thisMAP.addAnnotation(annotation)

    let annotation2 = Annotation()
    annotation2.coordinate = CLLocationCoordinate2D(latitude: 0.0, longitude: 1.0)
    annotation2.custom_image = false
    thisMAP.addAnnotation(annotation2)

    let annotation3 = Annotation()
    annotation3.coordinate = CLLocationCoordinate2D(latitude: 1.0, longitude:  0.0)
    annotation3.custom_image = false
    annotation3.color = MKPinAnnotationColor.green
    thisMAP.addAnnotation(annotation3)
}

func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
    if (annotation is MKUserLocation) {
        return nil
    }

    var anView = thisMAP.dequeueReusableAnnotationView(withIdentifier: reuseId )

    if anView == nil {
        if let anAnnotation = annotation as? Annotation {
            if anAnnotation.custom_image {
                let reuseId = "jj.png"
                anView = MKAnnotationView(annotation: annotation, reuseIdentifier: reuseId)
                anView.image = UIImage(named:"jj.png")
            }
            else {
                let reuseId = "pin"
                let pinView = MKPinAnnotationView(annotation: annotation, reuseIdentifier: reuseId)
                pinView.pinColor = anAnnotation.color
                anView = pinView
            }
        }
        anView.canShowCallout = false
    }
    else {
        anView.annotation = annotation

Answer 1

在这一行中，在这个地方不知道reuseID - 只在if-else块内，这就是为什么它是错误reuseId is a unresolved identifier：

    var anView = thisMAP.dequeueReusableAnnotationView(withIdentifier: reuseId )

您只能在定义它的范围内使用它。

将reuseID的定义放在此行之前！

它应与您在reuseId

中定义的if anAnnotation.custom_image {相同

mapkit中未解析的标识符

1 个答案: