ios - 如何在Swift 3.0中通过Segue从子类传递变量和对象

这是我的设置:ViewController-> SecondViewControoler

三个目标:

将图像添加到自定义注释(请参见下面的代码)

我有一个名为“Capital”的子类，我想在＃1中添加图像，然后创建其他变量来保存值，这些值将传递到新的SecondViewController，其中包括(2)个标签和一个Picker View:例如label1 =“text1”，label2 =“text2”，然后从包含多个对象(即Picker每行的标题)的数组中获取一个字符串

一旦用户点击自定义图钉上的标注按钮，我们便将ViewController推到名为“SecondViewController”的新ViewController上，并分配附加到自定义图钉上的子类“Capital”的值，该子图钉被窃听到新标签和选取器在SecondViewController中查看

到目前为止，这是我的代码:

名为“Capital.swift”的子类

import MapKit
import UIKit

class Capital: NSObject, MKAnnotation {
    var title: String?
    var coordinate: CLLocationCoordinate2D
    var info: String

    // here we would add the custom image in Goal #1
    // here we would add the (2) values for label1 and label2 in Goal #2
    // here we would add the array that contains multiple object in Goal #2

    init(title: String, coordinate: CLLocationCoordinate2D, info: String) {
        self.title = title
        self.coordinate = coordinate
        self.info = info

     // add additional lines as needed

    }
}

这是ViewController.swift的代码

import MapKit
import UIKit

class ViewController: UIViewController, MKMapViewDelegate {

    @IBOutlet var mapView: MKMapView!
    override func viewDidLoad() {
        super.viewDidLoad()

        let london = Capital(title: "London", coordinate: CLLocationCoordinate2D(latitude: 51.507222, longitude: -0.1275), info: "Home to the 2012 Summer Olympics.")
        let oslo = Capital(title: "Oslo", coordinate: CLLocationCoordinate2D(latitude: 59.95, longitude: 10.75), info: "Founded over a thousand years ago.")
        let paris = Capital(title: "Paris", coordinate: CLLocationCoordinate2D(latitude: 48.8567, longitude: 2.3508), info: "Often called the City of Light.")
        let rome = Capital(title: "Rome", coordinate: CLLocationCoordinate2D(latitude: 41.9, longitude: 12.5), info: "Has a whole country inside it.")
        let washington = Capital(title: "Washington DC", coordinate: CLLocationCoordinate2D(latitude: 38.895111, longitude: -77.036667), info: "Named after George himself.")

        mapView.addAnnotations([london, oslo, paris, rome, washington])
    }

    func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {

        let identifier = "Capital"
        if annotation is Capital {
            if let annotationView = mapView.dequeueReusableAnnotationView(withIdentifier: identifier) {
                annotationView.annotation = annotation
                return annotationView
            } else {
                let annotationView = MKPinAnnotationView(annotation:annotation, reuseIdentifier:identifier)
                annotationView.isEnabled = true
                annotationView.canShowCallout = true

                let btn = UIButton(type: .detailDisclosure)
                annotationView.rightCalloutAccessoryView = btn
                //annotationView.image = UIImage(named: "#imageLiteral(resourceName: ",pin,")")
            return annotationView
         }
       }
        return nil
    }

在这里，我们添加了特定于所按下城市的自定义标注变量，并将其推送到SecondViewController

func mapView(_ mapView: MKMapView, annotationView view: MKAnnotationView, calloutAccessoryControlTapped control: UIControl) {
        let capital = view.annotation as! Capital
        let placeName = capital.title
        let placeInfo = capital.info

        //Add custom image + (2) labels + and the array that contains multiple objects to be passed to the Picker 'view in the SecondViewController

        // Upon the User tapping the above button we push all the variables stored in Capital attached to the current city pin that was pressed to the new SecondViewController

        // Send the View Controller to the SecondViewController programically

        let SecondViewController = self.storyboard?.instantiateViewController(withIdentifier: "SecondViewController")
        self.show(SecondViewController!, sender: nil)
    }
}

这是我的SecondViewController代码

import UIKit
class ViewController: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource {
    @IBOutlet weak var pickerView: UIPickerView!
    var cityName = 0

//the values here are pulled from the custom pin that was pressed in the previous ViewController

var Array = ["object1 from custom pin","object2 from custom pin,","object3 from custom pin"]

@IBOutlet weak var label1: UILabel!
@IBOutlet weak var label2: UILabel!
override func viewDidLoad() {
    super.viewDidLoad()
    pickerView.delegate = self
    pickerView.dataSource = self
}

func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
    return Array[row]
}

func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
    return Array.count
}

func numberOfComponents(in pickerView: UIPickerView) -> Int {
    return 1
}

@IBAction func submit(_ sender: Any) {
    if (cityName == 0){
        label1.text = "object1 from custom pin"
    }
        else if(cityName == 1){
        label1.text = "object2 from custom pin"
    }
    else{
        label1.text = "object3 from custom pin"

继续...

    }
}

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    cityName = row
    }
}

感谢任何帮助

最佳答案

另一个选择是调用

"func performSegue(withIdentifier identifier: String, sender: Any?)"

这将触发从ViewController到
SecondViewController。这就是您希望在情节提要中在ViewController之间移动的代码保持不变，即，您控制了从ViewController拖动到SecondViewController的过程，以创建序列并为其指定唯一的ID。

每个UIViewController(的子类)都继承一个函数

"func prepare(for segue: UIStoryboardSegue, sender: Any?)"

这将由系统调用，您可以在此处添加
顾名思义，建议实施之前做好任何准备
执行特定的segue。此时下
ViewController已从情节提要板加载到内存中(但
尚未开始显示)。和的“segue” *参数"prepare(for segue: UIStoryboardSegue, sender: Any?)"实际上有一个
属性“目标”实际上是下一个ViewController。

不过要小心，因为您可能对此有1个以上的选择
将ViewController改为另一个NextController。
所以"segue.destination"可能不是您想要的SecondViewController，如果
您有1个以上的segue设置。因为系统调用
每个的"prepare(for segue: UIStoryboardSegue, sender: Any?)"segue离开当前的ViewController。确保您检查"segue.identifier"以确保您的后续代码正在处理
以您认为自己的身份进行测试。

现在您终于可以解决您的标题问题。
带有指向SecondViewController的指针，您可以自由设置任何
它拥有的 property ，这是您资本的特定实例
目的。要圈出一个圈，参数的“发送者” 参数"performSegue(withIdentifier identifier: String, sender: Any?)"*和"prepare(for segue: UIStoryboardSegue, sender: Any?)"实际上是
一样。因此，您实际上可以传递您喜欢的任何对象/结构
将“performSegue()”转换为“prepare(for :)”，只需将发送方对象转换为
确认“segue.identifier”后通过的类型。

func mapView(_ mapView: MKMapView, annotationView view: MKAnnotationView, calloutAccessoryControlTapped control: UIControl) {
    let capital = view.annotation as! Capital
    let placeName = capital.title
    let placeInfo = capital.info

    // Option 1
    perform segue.performSegue(withIdentifier: "SegueToSecondID", sender: capital)

    //Option 2 programmatically create SecondViewController and show.
    let SecondViewController = self.storyboard?.instantiateViewController(withIdentifier: "SecondViewController")
    SecondViewController.capital = capital
    self.show(SecondViewController!, sender: nil)
}

// If you are doing option 1
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "SegueToSecondID" && sender is Capital {
        let destination = segue.destination as SeconViewController
        destination.capital = sender
    }
}

class SecondViewController {
    //........
    var capital: Capital?  //Up to you if you want this as an optional

}

关于ios - 如何在Swift 3.0中通过Segue从子类传递变量和对象，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/46506741/