我对iOS和Objective-C以及整个MVC范式都是新手,我一直坚持以下几点:

我有一个充当数据输入表单的视图,我想让用户选择多个产品。产品列在另一个具有UITableViewController的视图中,我已启用多个选项。

如何将数据从一个视图传输到另一个视图?我会将UITableView上的选择保存在一个数组中,但如何将其传递回上一个数据输入表单视图,以便在提交表单时将其与其他数据一起保存到核心数据?

我在网上冲浪,看到一些人在应用程序委托中声明了一个数组。我读了一些关于单态的东西,但我不明白这些是什么,我读了关于创建数据模型的东西。

正确的执行方式是什么?我将如何执行?


当前回答

使用通知中心将数据从一个视图传递到另一个视图。

观察者-收听者模式效果最好。另一种解决方法是在两个类中创建相同的对象。

在类1中创建类2对象。访问要传递的数据对象,设置它们,然后按下视图控制器。

其他回答

您可以创建一个从源视图控制器到目标视图控制器的推送段,并提供如下标识符名称。

您必须像这样执行didselectRowAt的segue。

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    performSegue(withIdentifier: "segue", sender: self)
}

您可以从下面的函数传递选定项的数组。

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    let index = CategorytableView.indexPathForSelectedRow
    let indexNumber = index?.row
    print(indexNumber!)
    let VC = segue.destination as! AddTransactionVC
    VC.val = CategoryData[indexNumber!] . // Here you can pass the entire array instead of an array element.
}

您必须检查目标viewcontroller的viewdidload中的值,然后将其存储到数据库中。

override func viewDidLoad{
    if val != ""{
        btnSelectCategory.setTitle(val, for: .normal)
    }
}

要将数据从一个视图控制器(VC)发送到另一个,请使用以下简单方法:

YourNextVC *nxtScr = (YourNextVC*)[self.storyboard  instantiateViewControllerWithIdentifier:@"YourNextVC"];//Set this identifier from your storyboard

nxtScr.comingFrom = @"PreviousScreen"l
[self.navigationController nxtScr animated:YES];

雨燕5Matt Price的回答非常适合传递数据,但我我将在最新的Swift版本中重写它,因为我相信由于新的语法和方法/框架,正如最初的帖子在Objective-C中那样。

在视图控制器之间传递数据有多种选项。

使用导航控制器推送使用Segue使用代理使用通知查看器使用块

我将用最新的iOS框架在Swift中重写他的逻辑


通过导航控制器传递数据推送:从ViewControllerA到ViewControllerB

步骤1。在ViewControllerB中声明变量

var isSomethingEnabled = false

步骤2。在ViewControllerB的ViewDidLoad方法中打印变量

override func viewDidLoad() {
    super.viewDidLoad()
    // Print value received through segue, navigation push
    print("Value of 'isSomethingEnabled' from ViewControllerA: ", isSomethingEnabled)
}

步骤3。在ViewControllerA中通过导航控制器时传递数据

if let viewControllerB = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "ViewControllerB") as? ViewControllerB {
    viewControllerB.isSomethingEnabled = true
    if let navigator = navigationController {
        navigator.pushViewController(viewControllerB, animated: true)
    }
}

以下是完整的代码:

视图控制器A

import UIKit

class ViewControllerA: UIViewController  {

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    // MARK: Passing data through navigation PushViewController
    @IBAction func goToViewControllerB(_ sender: Any) {

        if let viewControllerB = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "ViewControllerB") as? ViewControllerB {
            viewControllerB.isSomethingEnabled = true
            if let navigator = navigationController {
                navigator.pushViewController(viewControllerB, animated: true)
            }
        }
    }
}

视图控制器B

import UIKit

class ViewControllerB: UIViewController {

    // MARK:  - Variable for Passing Data through Navigation push
    var isSomethingEnabled = false

    override func viewDidLoad() {
        super.viewDidLoad()
        // Print value received through navigation push
        print("Value of 'isSomethingEnabled' from ViewControllerA: ", isSomethingEnabled)
    }
}

通过Segue传递数据:从ViewControllerA到ViewControllerB

步骤1。创建从ViewControllerA到ViewControllerB的Segue,并在Storyboard中提供Identifier=showDetailSegue,如下所示

步骤2。在ViewControllerB中声明一个名为isSomethingEnabled的可行值并打印其值。

步骤3。在ViewControllerA中,传递Segue时传递SomethingEnabled的值

以下是完整的代码:

视图控制器A

import UIKit

class ViewControllerA: UIViewController  {

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    // MARK:  - - Passing Data through Segue  - -
    @IBAction func goToViewControllerBUsingSegue(_ sender: Any) {
        performSegue(withIdentifier: "showDetailSegue", sender: nil)
    }

    // Segue Delegate Method
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if (segue.identifier == "showDetailSegue") {
            let controller = segue.destination as? ViewControllerB
            controller?.isSomethingEnabled = true//passing data
        }
    }
}

视图控制器B

import UIKit

class ViewControllerB: UIViewController {
    var isSomethingEnabled = false

    override func viewDidLoad() {
        super.viewDidLoad()
        // Print value received through segue
        print("Value of 'isSomethingEnabled' from ViewControllerA: ", isSomethingEnabled)
    }
}

通过委托传递数据:从ViewControllerB到ViewControllerA

步骤1。在ViewControllerB文件中声明协议ViewControllerBDlegate,但在类之外

protocol ViewControllerBDelegate: NSObjectProtocol {

    // Classes that adopt this protocol MUST define
    // this method -- and hopefully do something in
    // that definition.
    func addItemViewController(_ controller: ViewControllerB?, didFinishEnteringItem item: String?)
}

步骤2。在ViewControllerB中声明委托变量实例

var delegate: ViewControllerBDelegate?

步骤3。在ViewControllerB的viewDidLoad方法中发送委托的数据

delegate?.addItemViewController(self, didFinishEnteringItem: "Data for ViewControllerA")

步骤4。确认ViewControllerB在ViewControllerA中保留

class ViewControllerA: UIViewController, ViewControllerBDelegate  {
// to do
}

步骤5。确认将在ViewControllerA中实现委托

if let viewControllerB = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "ViewControllerB") as? ViewControllerB {
    viewControllerB.delegate = self//confirming delegate
    if let navigator = navigationController {
        navigator.pushViewController(viewControllerB, animated: true)
    }
}

步骤6。实现用于在ViewControllerA中接收数据的委托方法

func addItemViewController(_ controller: ViewControllerB?, didFinishEnteringItem item: String?) {
    print("Value from ViewControllerB's Delegate", item!)
}

以下是完整的代码:

视图控制器A

import UIKit

class ViewControllerA: UIViewController, ViewControllerBDelegate  {

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    // Delegate method
    func addItemViewController(_ controller: ViewControllerB?, didFinishEnteringItem item: String?) {
        print("Value from ViewControllerB's Delegate", item!)
    }

    @IBAction func goToViewControllerForDelegate(_ sender: Any) {

        if let viewControllerB = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "ViewControllerB") as? ViewControllerB {
            viewControllerB.delegate = self
            if let navigator = navigationController {
                navigator.pushViewController(viewControllerB, animated: true)
            }
        }
    }
}

视图控制器B

import UIKit

//Protocol decleare
protocol ViewControllerBDelegate: NSObjectProtocol {
    // Classes that adopt this protocol MUST define
    // this method -- and hopefully do something in
    // that definition.
    func addItemViewController(_ controller: ViewControllerB?, didFinishEnteringItem item: String?)
}

class ViewControllerB: UIViewController {
    var delegate: ViewControllerBDelegate?

    override func viewDidLoad() {
        super.viewDidLoad()
        // MARK:  - - - -  Set Data for Passing Data through Delegate  - - - - - -
        delegate?.addItemViewController(self, didFinishEnteringItem: "Data for ViewControllerA")
    }
}

通过通知查看器传递数据:从ViewControllerB到ViewControllerA

步骤1。在ViewControllerB中的通知查看器中设置和发布数据

let objToBeSent = "Test Message from Notification"
        NotificationCenter.default.post(name: Notification.Name("NotificationIdentifier"), object: objToBeSent)

步骤2。在ViewControllerA中添加通知查看器

NotificationCenter.default.addObserver(self, selector: #selector(self.methodOfReceivedNotification(notification:)), name: Notification.Name("NotificationIdentifier"), object: nil)

步骤3。在ViewControllerA中接收通知数据值

@objc func methodOfReceivedNotification(notification: Notification) {
    print("Value of notification: ", notification.object ?? "")
}

以下是完整的代码:

视图控制器A

import UIKit

class ViewControllerA: UIViewController{

    override func viewDidLoad() {
        super.viewDidLoad()

        // Add observer in controller(s) where you want to receive data
        NotificationCenter.default.addObserver(self, selector: #selector(self.methodOfReceivedNotification(notification:)), name: Notification.Name("NotificationIdentifier"), object: nil)
    }

    // MARK: Method for receiving Data through Post Notification
    @objc func methodOfReceivedNotification(notification: Notification) {
        print("Value of notification: ", notification.object ?? "")
    }
}

视图控制器B

import UIKit

class ViewControllerB: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        // MARK:Set data for Passing Data through Post Notification
        let objToBeSent = "Test Message from Notification"
        NotificationCenter.default.post(name: Notification.Name("NotificationIdentifier"), object: objToBeSent)
    }
}

通过块传递数据:从ViewControllerB到ViewControllerA

步骤1。在ViewControllerB中声明块

var authorizationCompletionBlock:((Bool)->())? = {_ in}

步骤2。在ViewControllerB中设置块中的数据

if authorizationCompletionBlock != nil
{
    authorizationCompletionBlock!(true)
}

步骤3。在ViewControllerA中接收块数据

// Receiver Block
controller!.authorizationCompletionBlock = { isGranted in
    print("Data received from Block is: ", isGranted)
}

以下是完整的代码:

视图控制器A

import UIKit

class ViewControllerA: UIViewController  {

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    // MARK:Method for receiving Data through Block
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if (segue.identifier == "showDetailSegue") {
            let controller = segue.destination as? ViewControllerB
            controller?.isSomethingEnabled = true

            // Receiver Block
            controller!.authorizationCompletionBlock = { isGranted in
                print("Data received from Block is: ", isGranted)
            }
        }
    }
}

视图控制器B

import UIKit

class ViewControllerB: UIViewController {

    // MARK: Variable for Passing Data through Block
    var authorizationCompletionBlock:((Bool)->())? = {_ in}

    override func viewDidLoad() {
        super.viewDidLoad()

        // MARK: Set data for Passing Data through Block
        if authorizationCompletionBlock != nil
        {
            authorizationCompletionBlock!(true)
        }
    }
}

你可以在我的GitHub上找到完整的示例应用程序。如果你对此有任何疑问,请告诉我。

我喜欢基于NSProxy的模型对象和模拟对象的想法,以便在用户选择的内容可以取消时提交或丢弃数据。

传递数据很容易,因为它是一个对象或两个对象,如果你有一个UINavigationController控制器,你可以将对模型的引用保存在内部,所有推送视图控制器都可以直接从导航控制器访问它。

经过更多的研究,协议和代表似乎是正确的/苹果首选的方式。

我最终使用了这个示例(在iPhone开发SDK中):

在视图控制器和其他对象之间共享数据

它工作得很好,允许我在视图之间前后传递字符串和数组。