無法識別的選擇器swift

Question

我已經閱讀了關於此主題的以前的文章，並且我確保我的代碼不包含相同的錯誤，但當我嘗試點擊時，我一直收到錯誤「無法識別的選擇器發送到實例」我的UIButton。任何人都可以弄清楚是什麼問題？我確定我的動作名稱和簽名與我連接到我的按鈕的功能完全相同。我試過重新啓動XCode，但它仍然無法工作。任何輸入讚賞。

import UIKit 
import MapKit 

class MapViewController: UIViewController { 

    var mapView: MKMapView! 

    override func loadView() { 

     //create an instance of the MkMapView class and set it as the view controllers view 
     mapView = MKMapView() 
     view = mapView 

     //create a set of segmented controls to the map interface to give the user some options regarding their map 
     let segmentedControls = UISegmentedControl(items: ["Satellite", "Standard", "Hybrid"]) 

     //set the color of the segemented controls and set which index they default to on launch 
     segmentedControls.backgroundColor = UIColor.whiteColor().colorWithAlphaComponent(0.5) 
     segmentedControls.selectedSegmentIndex = 0 

     //how auto-layout used to work was each view would have an auto-resizing mask that iOS would look at and add constraints onto the view based on its mask. The problem is now that we can manually add constraints ourselves, we run into conflicts in the layout between the constraints we set out and those iOS sets up itself through the mask. The best way to avoid this is to simply set the translatesAutoreszing... property to "false" so that iOS doesn't create its own constraints and only ours get set in the project 
     segmentedControls.translatesAutoresizingMaskIntoConstraints = false 

     //add the segmentedControl to the main view 
     view.addSubview(segmentedControls) 

     //use the view margins to set the insets of the segmented controls- that way they'll adapt to the margins of whatever screen the ap loads on 
     let margins = view.layoutMarginsGuide 

     //create a set of constraints for the segmented controls 
     let topConstraint = segmentedControls.topAnchor.constraintEqualToAnchor(topLayoutGuide.bottomAnchor, constant: 8) 
     let leadConstraint = segmentedControls.leadingAnchor.constraintEqualToAnchor(margins.leadingAnchor) 
     let traiConstraint = segmentedControls.trailingAnchor.constraintEqualToAnchor(margins.trailingAnchor) 

     //activate the constraints 
     topConstraint.active = true 
     leadConstraint.active = true 
     trailConstraint.active = true 

     //create a UIButton, set its label, and add it to the view hierarchy 
     let button = UIButton(type: .System) 
     button.setTitle("Show Location", forState: .Normal) 
     button.translatesAutoresizingMaskIntoConstraints = false 
     view.addSubview(button) 

     //create constraints and set them to active 
     let buttonBottomConstraint = button.bottomAnchor.constraintEqualToAnchor(bottomLayoutGuide.topAnchor) 
     let buttonLeadConstraint = button.leadingAnchor.constraintEqualToAnchor(margins.leadingAnchor) 
     let buttonTrailConstraint = button.trailingAnchor.constraintEqualToAnchor(margins.trailingAnchor); 

     buttonBottomConstraint.active = true 
     buttonLeadConstraint.active = true 
     buttonTrailConstraint.active = true 

     //set the action-target connection 
     button.addTarget(self, action: "zoomToUser:", forControlEvents: UIControlEvents.TouchUpInside) 

     func zoomToUser(sender: UIButton!) { 
      mapView.showsUserLocation = true 
     } 
    } 

    override func viewDidLoad() { 
     super.viewDidLoad() 
     print("Loaded map view") 

    } 
} 

Answer 1

您的操作引用的函數位於錯誤的範圍內。只需帶上

func zoomToUser(sender: UIButton!) { 
    mapView.showsUserLocation = true 
} 

以外的override func loadView()功能。

因爲你的函數只在loadView運行時才存在，所以當你真正點擊按鈕時它不可用。

Answer 2

聲明函數的loadView方法外

override func loadView() { 
} 

func zoomToUser(sender: UIButton!) { 
      mapView.showsUserLocation = true 
     }