Swift-在协议/委托之间传递数据时出错（发现为零）_Swift_Null_Delegates_Protocols

Swift-在协议/委托之间传递数据时出错（发现为零）

swift

Swift-在协议/委托之间传递数据时出错（发现为零）,swift,null,delegates,protocols,Swift,Null,Delegates,Protocols,我正在用swift 3.0开发一个应用程序。我想做的是，从“MainMapVC”类，这是一个视图，其中有一个带有日期滑块的地图（请参见附件）。我想移动滑块并将滑块位置（1、2或3）发送到LeftSideViewController，它是根据所选日期更新内容的侧视图（图例） MainMapVC的视图： import UIKit protocol MainMapVCDelegate: class { func moveSliderDates(datePos: Int) } clas

我正在用swift 3.0开发一个应用程序。我想做的是，从“MainMapVC”类，这是一个视图，其中有一个带有日期滑块的地图（请参见附件）。我想移动滑块并将滑块位置（1、2或3）发送到LeftSideViewController，它是根据所选日期更新内容的侧视图（图例）

MainMapVC的视图：

import UIKit

protocol MainMapVCDelegate: class {

    func moveSliderDates(datePos: Int)

}


class MainMapVC: UIViewController, UISearchBarDelegate, CLLocationManagerDelegate, GMSMapViewDelegate {

//MARK: VARIABLES
weak var delegate: MainMapVCDelegate? = nil


let step: Float = 1
@IBAction func moveSliderDates(_ sender: UISlider) {
    let roundedValue = round(sender.value / step) * step
    sender.value = roundedValue 
    delegate?.moveSliderDates(datePos: Int(roundedValue))      

}

}

import UIKit

class LeftSideViewController: UIViewController, UITableViewDataSource, UITableViewDelegate, customCellDelegate, MainMapVCDelegate {

 override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "MainMapVC" {
        let secondViewController = segue.destination as! MainMapVC
        secondViewController.delegate = self
    }
}

func moveSliderDates(datePos: Int){
    print(datePos)
    print("/////////////")
    tableSideLeft.reloadData()
}

 let step: Float = 1
 @IBAction func moveSliderDates(_ sender: UISlider) {
    let roundedValue = round(sender.value / step) * step
    sender.value = roundedValue

    let data:[String: Int] = ["data": Int(roundedValue)]
    NotificationCenter.default.post(name: NSNotification.Name(rawValue: "notificationName"), object: nil, userInfo: data)

}

    func listnerFunction(_ notification: NSNotification) {
    if let data = notification.userInfo?["data"] as? String {
        print(data)
    }



override func viewDidLoad() {
    super.viewDidLoad()
    NotificationCenter.default.addObserver(self, selector: #selector(listnerFunction(_:)), name: NSNotification.Name(rawValue: "notificationName"), object: nil)
}

带有图例的MainMapVC视图：

import UIKit

protocol MainMapVCDelegate: class {

    func moveSliderDates(datePos: Int)

}


class MainMapVC: UIViewController, UISearchBarDelegate, CLLocationManagerDelegate, GMSMapViewDelegate {

//MARK: VARIABLES
weak var delegate: MainMapVCDelegate? = nil


let step: Float = 1
@IBAction func moveSliderDates(_ sender: UISlider) {
    let roundedValue = round(sender.value / step) * step
    sender.value = roundedValue 
    delegate?.moveSliderDates(datePos: Int(roundedValue))      

}

}

import UIKit

class LeftSideViewController: UIViewController, UITableViewDataSource, UITableViewDelegate, customCellDelegate, MainMapVCDelegate {

 override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "MainMapVC" {
        let secondViewController = segue.destination as! MainMapVC
        secondViewController.delegate = self
    }
}

func moveSliderDates(datePos: Int){
    print(datePos)
    print("/////////////")
    tableSideLeft.reloadData()
}

 let step: Float = 1
 @IBAction func moveSliderDates(_ sender: UISlider) {
    let roundedValue = round(sender.value / step) * step
    sender.value = roundedValue

    let data:[String: Int] = ["data": Int(roundedValue)]
    NotificationCenter.default.post(name: NSNotification.Name(rawValue: "notificationName"), object: nil, userInfo: data)

}

    func listnerFunction(_ notification: NSNotification) {
    if let data = notification.userInfo?["data"] as? String {
        print(data)
    }



override func viewDidLoad() {
    super.viewDidLoad()
    NotificationCenter.default.addObserver(self, selector: #selector(listnerFunction(_:)), name: NSNotification.Name(rawValue: "notificationName"), object: nil)
}

现在我必须在两个视图控制器之间传递一个值。但问题是，我得到了错误“致命错误：在展开可选值时意外发现nil”。基本上我有一个“零”代表

weak var delegate: LeftSideDelegate? = nil

但是，请不要找到错误所在，因为委托的定义类似于“var delegate:mainmapvcdegate！”，我在“MainMapVC”类中将其称为“delegate.moveSliderDates（datePos:Int（roundedValue））”

有人知道我在代表发言中失败的地方吗？谢谢：）

我附加了这两个类的代码，以便您看到整个代码

Class MainMapVC（第一种方式）：

import UIKit

protocol MainMapVCDelegate: class {

    func moveSliderDates(datePos: Int)

}


class MainMapVC: UIViewController, UISearchBarDelegate, CLLocationManagerDelegate, GMSMapViewDelegate {

//MARK: VARIABLES
weak var delegate: MainMapVCDelegate? = nil


let step: Float = 1
@IBAction func moveSliderDates(_ sender: UISlider) {
    let roundedValue = round(sender.value / step) * step
    sender.value = roundedValue 
    delegate?.moveSliderDates(datePos: Int(roundedValue))      

}

}

import UIKit

class LeftSideViewController: UIViewController, UITableViewDataSource, UITableViewDelegate, customCellDelegate, MainMapVCDelegate {

 override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "MainMapVC" {
        let secondViewController = segue.destination as! MainMapVC
        secondViewController.delegate = self
    }
}

func moveSliderDates(datePos: Int){
    print(datePos)
    print("/////////////")
    tableSideLeft.reloadData()
}

 let step: Float = 1
 @IBAction func moveSliderDates(_ sender: UISlider) {
    let roundedValue = round(sender.value / step) * step
    sender.value = roundedValue

    let data:[String: Int] = ["data": Int(roundedValue)]
    NotificationCenter.default.post(name: NSNotification.Name(rawValue: "notificationName"), object: nil, userInfo: data)

}

    func listnerFunction(_ notification: NSNotification) {
    if let data = notification.userInfo?["data"] as? String {
        print(data)
    }



override func viewDidLoad() {
    super.viewDidLoad()
    NotificationCenter.default.addObserver(self, selector: #selector(listnerFunction(_:)), name: NSNotification.Name(rawValue: "notificationName"), object: nil)
}

moveSliderDates函数中的委托值为“nil”：

delegate?.moveSliderDates(datePos: Int(roundedValue))

类LeftSideViewController（第一种方式）：

import UIKit

protocol MainMapVCDelegate: class {

    func moveSliderDates(datePos: Int)

}


class MainMapVC: UIViewController, UISearchBarDelegate, CLLocationManagerDelegate, GMSMapViewDelegate {

//MARK: VARIABLES
weak var delegate: MainMapVCDelegate? = nil


let step: Float = 1
@IBAction func moveSliderDates(_ sender: UISlider) {
    let roundedValue = round(sender.value / step) * step
    sender.value = roundedValue 
    delegate?.moveSliderDates(datePos: Int(roundedValue))      

}

}

import UIKit

class LeftSideViewController: UIViewController, UITableViewDataSource, UITableViewDelegate, customCellDelegate, MainMapVCDelegate {

 override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "MainMapVC" {
        let secondViewController = segue.destination as! MainMapVC
        secondViewController.delegate = self
    }
}

func moveSliderDates(datePos: Int){
    print(datePos)
    print("/////////////")
    tableSideLeft.reloadData()
}

 let step: Float = 1
 @IBAction func moveSliderDates(_ sender: UISlider) {
    let roundedValue = round(sender.value / step) * step
    sender.value = roundedValue

    let data:[String: Int] = ["data": Int(roundedValue)]
    NotificationCenter.default.post(name: NSNotification.Name(rawValue: "notificationName"), object: nil, userInfo: data)

}

    func listnerFunction(_ notification: NSNotification) {
    if let data = notification.userInfo?["data"] as? String {
        print(data)
    }



override func viewDidLoad() {
    super.viewDidLoad()
    NotificationCenter.default.addObserver(self, selector: #selector(listnerFunction(_:)), name: NSNotification.Name(rawValue: "notificationName"), object: nil)
}

由于“MainVC”的委托为“nil”，因此不能进入此函数内部：

import UIKit

protocol MainMapVCDelegate: class {

    func moveSliderDates(datePos: Int)

}


class MainMapVC: UIViewController, UISearchBarDelegate, CLLocationManagerDelegate, GMSMapViewDelegate {

//MARK: VARIABLES
weak var delegate: MainMapVCDelegate? = nil


let step: Float = 1
@IBAction func moveSliderDates(_ sender: UISlider) {
    let roundedValue = round(sender.value / step) * step
    sender.value = roundedValue 
    delegate?.moveSliderDates(datePos: Int(roundedValue))      

}

}

import UIKit

class LeftSideViewController: UIViewController, UITableViewDataSource, UITableViewDelegate, customCellDelegate, MainMapVCDelegate {

 override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "MainMapVC" {
        let secondViewController = segue.destination as! MainMapVC
        secondViewController.delegate = self
    }
}

func moveSliderDates(datePos: Int){
    print(datePos)
    print("/////////////")
    tableSideLeft.reloadData()
}

 let step: Float = 1
 @IBAction func moveSliderDates(_ sender: UISlider) {
    let roundedValue = round(sender.value / step) * step
    sender.value = roundedValue

    let data:[String: Int] = ["data": Int(roundedValue)]
    NotificationCenter.default.post(name: NSNotification.Name(rawValue: "notificationName"), object: nil, userInfo: data)

}

    func listnerFunction(_ notification: NSNotification) {
    if let data = notification.userInfo?["data"] as? String {
        print(data)
    }



override func viewDidLoad() {
    super.viewDidLoad()
    NotificationCenter.default.addObserver(self, selector: #selector(listnerFunction(_:)), name: NSNotification.Name(rawValue: "notificationName"), object: nil)
}

Class MainMapVC（第二种方式）：

import UIKit

protocol MainMapVCDelegate: class {

    func moveSliderDates(datePos: Int)

}


class MainMapVC: UIViewController, UISearchBarDelegate, CLLocationManagerDelegate, GMSMapViewDelegate {

//MARK: VARIABLES
weak var delegate: MainMapVCDelegate? = nil


let step: Float = 1
@IBAction func moveSliderDates(_ sender: UISlider) {
    let roundedValue = round(sender.value / step) * step
    sender.value = roundedValue 
    delegate?.moveSliderDates(datePos: Int(roundedValue))      

}

}

import UIKit

class LeftSideViewController: UIViewController, UITableViewDataSource, UITableViewDelegate, customCellDelegate, MainMapVCDelegate {

 override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "MainMapVC" {
        let secondViewController = segue.destination as! MainMapVC
        secondViewController.delegate = self
    }
}

func moveSliderDates(datePos: Int){
    print(datePos)
    print("/////////////")
    tableSideLeft.reloadData()
}

 let step: Float = 1
 @IBAction func moveSliderDates(_ sender: UISlider) {
    let roundedValue = round(sender.value / step) * step
    sender.value = roundedValue

    let data:[String: Int] = ["data": Int(roundedValue)]
    NotificationCenter.default.post(name: NSNotification.Name(rawValue: "notificationName"), object: nil, userInfo: data)

}

    func listnerFunction(_ notification: NSNotification) {
    if let data = notification.userInfo?["data"] as? String {
        print(data)
    }



override func viewDidLoad() {
    super.viewDidLoad()
    NotificationCenter.default.addObserver(self, selector: #selector(listnerFunction(_:)), name: NSNotification.Name(rawValue: "notificationName"), object: nil)
}

类LeftSideViewController（第二种方式）：

import UIKit

protocol MainMapVCDelegate: class {

    func moveSliderDates(datePos: Int)

}


class MainMapVC: UIViewController, UISearchBarDelegate, CLLocationManagerDelegate, GMSMapViewDelegate {

//MARK: VARIABLES
weak var delegate: MainMapVCDelegate? = nil


let step: Float = 1
@IBAction func moveSliderDates(_ sender: UISlider) {
    let roundedValue = round(sender.value / step) * step
    sender.value = roundedValue 
    delegate?.moveSliderDates(datePos: Int(roundedValue))      

}

}

import UIKit

class LeftSideViewController: UIViewController, UITableViewDataSource, UITableViewDelegate, customCellDelegate, MainMapVCDelegate {

 override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "MainMapVC" {
        let secondViewController = segue.destination as! MainMapVC
        secondViewController.delegate = self
    }
}

func moveSliderDates(datePos: Int){
    print(datePos)
    print("/////////////")
    tableSideLeft.reloadData()
}

 let step: Float = 1
 @IBAction func moveSliderDates(_ sender: UISlider) {
    let roundedValue = round(sender.value / step) * step
    sender.value = roundedValue

    let data:[String: Int] = ["data": Int(roundedValue)]
    NotificationCenter.default.post(name: NSNotification.Name(rawValue: "notificationName"), object: nil, userInfo: data)

}

    func listnerFunction(_ notification: NSNotification) {
    if let data = notification.userInfo?["data"] as? String {
        print(data)
    }



override func viewDidLoad() {
    super.viewDidLoad()
    NotificationCenter.default.addObserver(self, selector: #selector(listnerFunction(_:)), name: NSNotification.Name(rawValue: "notificationName"), object: nil)
}

从不进入函数列表功能

您会收到错误，因为您通过以下代码将委托定义为强制展开noy nil版本

var delegate:LeftSideDelegate
相反，你需要像这样改变它。您不应该为代理创建强引用循环
weak var delegate: LeftSideDelegate? = nil

然后，对所有委托调用执行包装版本委托调用
delegate?.changeZindexDelivery()

除此之外，将行protocolleftsidedelegate{
更改为protocolleftsidedelegate:class{

使用委托在视图控制器之间传递数据
首先，在要将数据传递给另一个视图控制器的类中，以这种方式声明协议
protocol SampleDelegate: class {
    func delegateFunctionCall(data: String)
}

然后，使用弱变量类型将委托变量创建为可选变量。若要传递数据或触发操作，请使用调用委托方法
class SecondViewController: UIViewController {

    weak var delegate: SampleDelegate? = nil

    @IBAction func sendTextBackButton(sender: AnyObject) {
        delegate?.delegateFunctionCall(data: textField.text!)

    }
}

最后，在要接收操作或数据的视图控制器中，实现协议。当启动第二个视图控制器时，将其委托变量设置为当前视图控制器
class FirstViewController: UIViewController, SampleDelegate {

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == "showSecondViewController" {
            let secondViewController = segue.destination as! SecondViewController
            secondViewController.delegate = self
        }
    }

    func delegateFunctionCall(data: String) {
        label.text = data
    }
}

使用通知在视图控制器之间传递数据
在目标视图控制器中，注册准备好调用的处理程序函数。您可以在视图加载中添加此注册代码
NotificationCenter.default.addObserver(self, selector: #selector(listnerFunction(_:)), name: NSNotification.Name(rawValue: "notificationName"), object: nil)

func listnerFunction(_ notification: NSNotification) {
    if let data = notification.userInfo?["data"] as? String {
        // do something with your data   
    }
}

然后在另一个视图控制器中，如果要传递数据，只需调用
let data:[String: String] = ["data": "YourData"]
NotificationCenter.default.post(name: NSNotification.Name(rawValue: "notificationName"), object: nil, userInfo: data) 

@JordiGallenRenau您正在分机中接收此协议调用，对吗？（extension MainMapVC:LeftSideDelegate
）在里面放一个断点，看看它是否被调用。顺便说一句，你说你不能调用moveSliderDates函数是什么意思？这会给你带来一些错误？@jordigallenreneu哦，所以你需要为你的主视图控制器准备一个segue方法。目标必须是你的左视图控制器。然后你需要执行destinationViewController.delegate=self@JordiGallenRenau您仍然无法使其工作吗？您没有使用segue吗？您希望从main到left传递数据，因此您需要的是，在您的left view控制器上定义协议，创建委托变量并对其调用方法。然后在您的maincontroller上，将main本身设置为left view控制器的委托对象呃，我被你的观点弄糊涂了code@JordiGallenRenau我已经更新了两种在视图控制器之间传递数据的正常方式。如果这有帮助，请将其标记为正确答案。如果仍然不正确，请告诉我work@JordiGallenRenau当目标视图控制器运行时，是否尝试调用委托方法尚未初始化？这两种方法仅在源视图控制器和目标视图控制器有效时才起作用