通过分段控制改变地图类型(混合，卫星)

Question

我正试图使用分段控制按钮改变地图类型，我希望它能改变3个选项的地图类型:标准，卫星和混合。到目前为止，我有这段代码，但一旦选择了不同的映射类型，什么也不会发生:

@IBAction func segmentedControlAction(sender: UISegmentedControl!) {
    if sender.selectedSegmentIndex == 0{
        mapView.mapType = MKMapType.Standard
    }
    else if sender.selectedSegmentIndex == 1{
        mapView.mapType = MKMapType.Satellite
    }
    else if sender.selectedSegmentIndex == 3{
        mapView.mapType = MKMapType.Hybrid
    }
}

我是Swift和Xcode的新手，所以任何帮助都很感激:)

谢谢

Answer 1

首先，确保在分段控件选择更改时正在调用您的方法。很容易忘记挂起outlet方法。一旦您验证了这一点，请记住地图数据是异步加载的，因此您可能不会在选择不同的模式后立即看到它的变化。但是，使用您发布的代码，您将永远不会看到.Hybrid类型，因为3段控件中的selectedSegmentIndex将永远不会为3。

实现此方法的更简洁的方法是:

@IBAction func segmentedControlAction(sender: UISegmentedControl!) {
    switch (sender.selectedSegmentIndex) {
        case 0:
            mapView.mapType = .Standard
        case 1:
            mapView.mapType = .Satellite
        default:
            mapView.mapType = .Hybrid
    }
}

注意Swift不需要break语句在每个case的末尾。

编辑:Swift 4.1

@IBAction func mapTypeSegmentSelected(_ sender: UISegmentedControl) {
        switch sender.selectedSegmentIndex {
        case 0:
            mapView.mapType = .standard
        case 1:
            mapView.mapType = .satellite
        default:
            mapView.mapType = .hybrid
        }
    }

Answer 2

import CoreLocation
import MapKit
class ViewController: UIViewController,CLLocationManagerDelegate,MKMapViewDelegate {
    @IBOutlet weak var my_map: MKMapView!
    var my_location = CLLocationManager()
    enum maptype:NSInteger
    {
        case standardmap = 0
        case satellitemap = 1
        case hybridmap = 2
    }
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        self.my_map.showsUserLocation = true
        self.my_map.delegate = self    
        self.my_location = CLLocationManager.init()
        self.my_location.delegate = self
        self.my_location.requestWhenInUseAuthorization()
        self.my_location.stopUpdatingLocation()            
        let location = CLLocationCoordinate2DMake(11.004556, 76.961632)
        let span = MKCoordinateSpanMake(0.1, 0.1)
        let region = MKCoordinateRegionMake(location, span)
        my_map.setRegion(region, animated: true)
        let annotation = MKPointAnnotation()
        annotation.coordinate = location
        annotation.title = "coimbatore"
        annotation.subtitle = "manchester city"
        my_map.addAnnotation(annotation)    
    }
    func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView?
    {    
        /*let annotationview = MKAnnotationView(annotation: annotation, reuseIdentifier: "pin")
        annotationview.image = UIImage(named:"nature.jpeg")
        //let transform = CGAffineTransform(scaleX: 0.1, y: 0.1)
        //annotationview.transform = transform
        return annotationview*/
        let annotationReuseId = "Place"
        var anView = mapView.dequeueReusableAnnotationView(withIdentifier: annotationReuseId)
        if anView == nil {
            anView = MKAnnotationView(annotation: annotation, reuseIdentifier: annotationReuseId)
        } else {
            anView?.annotation = annotation
        }
        anView?.image = UIImage(named: "annotation")
        let transform = CGAffineTransform(scaleX: 0.1, y: 0.1)
        anView?.transform = transform
        anView?.backgroundColor = UIColor.clear
        anView?.canShowCallout = false
        return anView
    }
    @IBAction func maptypes(_ sender: Any)
    {
        switch(sender as AnyObject).selectedSegmentIndex
        {
        case maptype.standardmap.rawValue:
            my_map.mapType = .standard
        case maptype.satellitemap.rawValue:
            my_map.mapType = .satellite
        case maptype.hybridmap.rawValue:
            my_map.mapType = .hybrid
        default:
            break
        }
    }