Swift iOS Mapkit-注解未显示

Question

Having some trouble getting the annotation to appear on the map. The address string is getting passed in from the previous ViewController. Everything working fine up to pushing the annotation to the map. Any suggestions?

class PostViewController: UIViewController {
@IBOutlet weak var locationInput: UITextField!
@IBOutlet weak var debugText: UILabel!


@IBAction func postDirectionTouched(sender: AnyObject) {
    if locationInput.text!.isEmpty {
        debugText.text = "Location Input Empty."
    } else {
        nextSegue()
    }

}

func nextSegue() {
    dispatch_async(dispatch_get_main_queue(), {
        let controller = self.storyboard!.instantiateViewControllerWithIdentifier("LinkPostController") as! LinkPostViewController
        controller.address = self.locationInput.text!
        self.presentViewController(controller, animated: true, completion: nil)
    })
}

}

---

import UIKit
import CoreLocation
import AddressBook
import MapKit

class LinkPostViewController: UIViewController, MKMapViewDelegate {

@IBOutlet weak var pointMap: MKMapView!
@IBOutlet weak var linkInput: UITextField!
@IBOutlet weak var debugText: UILabel!
var address: String = ""
var coords: CLLocationCoordinate2D?

override func viewDidLoad() {
    super.viewDidLoad()

    self.mapLocation()

}

func mapLocation(){
    let geocoder = CLGeocoder()

    geocoder.geocodeAddressString(self.address, completionHandler: {(placemark, error) -> Void in
        if error != nil{
            print("Geocode failed with error: \(error!.localizedDescription)")
        } else if placemark!.count > 0 {
            let pm = placemark?[0]
            let location = pm!.location
            self.coords = location!.coordinate

            print(self.coords!)

            self.showMap()


        }

    })
}

func showMap() {
        print("last")
        let coordinates = self.coords
        let pinn = MKPointAnnotation()
        pinn.title = "hello"
        pinn.subtitle = "This my pin."
        pinn.coordinate = coordinates!



        dispatch_async(dispatch_get_main_queue()) {
            self.pointMap.addAnnotation(pinn)
        }
   }
func mapView(mapView: MKMapView, annotationView: MKAnnotationView, calloutAccessoryControlTapped control: UIControl) {}
}

Answer 1

Simplest working example, adds an annotation in Australia:

import UIKit
import MapKit

class ViewController: UIViewController {

    // MARK: - Private variables

    private var mapView: MKMapView?

    // MARK: - UIViewController methods

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

        mapView = MKMapView(frame: view.frame)
        view.addSubview(mapView!)
        let locationCoordinate = CLLocationCoordinate2DMake(-25.27, 133.775)
        let pointAnnotation = MKPointAnnotation()
        pointAnnotation.coordinate = locationCoordinate
        mapView?.addAnnotation(pointAnnotation)
    }
}

check placemark!.count > 0 (your code looks correct)