swift - 如何从不同的 View Controller 调用函数？

Question

我有一个基本上是一个笔记应用程序，我试图从另一个 View Controller 调用一个 View Controller 中的函数。我该如何做到这一点，或者我应该有更好的方法吗？

这是我尝试调用该函数的地方

class NoteDetailViewController: UIViewController
{
    @IBOutlet weak var funcButton: UIButton!

    @IBAction func funcButTouched(sender: UIButton)
    {
     // where i want to call the function
    }
}

函数在哪里

class ListTableViewController: UITableViewController
{
    // the function
    func wordCount()
    {
        var contentArr = Project.sharedInstance.content.componentsSeparatedByString(" ")
        for (index, element) in contentArr.enumerate()
        {
            let location = conciseArr.indexOf(element)
            if (location != nil)
            {
                contentArr[index] = inflatedArr[location!]
                afterStr = contentArr.joinWithSeparator(" ")
                Project.sharedInstance.after = afterStr
            }
        }
    }
}

我尝试过创建 ListTableViewController 的实例并以这种方式调用该函数，但出现错误。

Answer 1

您可以使用delegation .

首先，声明一个委托(delegate)协议(protocol)。这应该位于您的 NoteDetailViewController.swift 文件中，但位于 class 声明之外:

protocol NoteDetailViewControllerDelegate: class {
    func noteDetailViewControllerButtonTouched(controller: NoteDetailViewController)
}

接下来，将委托(delegate)属性添加到您的 NoteDetailViewController:

weak var delegate: NoteDetailViewControllerDelegate?

现在，我们使用@IBAction来告诉委托(delegate)，这将是ListTableViewController:

@IBAction func funcButTouched(sender: UIButton)
{
    delegate?.noteDetailViewControllerButtonTouched(self)
}

最后，回到 ListTableViewController (假设该 Controller 是在显示 NoteDetailViewController 之前的 Controller )，遵守协议(protocol)并使用 prepareForSegue > 将委托(delegate)设置为其自身:

class ListTableViewController: UITableViewController, NoteDetailViewControllerDelegate {
    // ... more stuff ...

    // Implement the delegate protocol
    func noteDetailViewControllerButtonTouched(controller: NoteDetailViewController) {
        // Do something! The button was pressed! 
        wordCount()
    }
    // Set ourselves as delegate when we are about to show the other view controller
    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        if let yourVC = segue.destinationViewController as? NoteDetailViewController {
            yourVC.delegate = self
        }
    }
}

<小时/>

你应该以这样的方式结束:

NoteDetailViewController.swift:

class NoteDetailViewController: UIViewController
{
    @IBOutlet weak var funcButton: UIButton!
    weak var delegate: NoteDetailViewControllerDelegate?

    @IBAction func funcButTouched(sender: UIButton)
    {
        delegate?.noteDetailViewControllerButtonTouched(self)
    }
}

protocol NoteDetailViewControllerDelegate: class {
    func noteDetailViewControllerButtonTouched(controller: NoteDetailViewController)
}

ListTableViewController.swift:

class ListTableViewController: UITableViewController, NoteDetailViewControllerDelegate
{
    // the function
    func wordCount()
    {
        var contentArr = Project.sharedInstance.content.componentsSeparatedByString(" ")
        for (index, element) in contentArr.enumerate()
        {
            let location = conciseArr.indexOf(element)
            if (location != nil)
            {
                contentArr[index] = inflatedArr[location!]
                afterStr = contentArr.joinWithSeparator(" ")
                Project.sharedInstance.after = afterStr
            }
        }
    }
    // Implement the delegate protocol
    func noteDetailViewControllerButtonTouched(controller: NoteDetailViewController) {
        // Do something! The button was pressed! 
        wordCount()
    }
    // Set ourselves as delegate when we are about to show the other view controller
    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        if let yourVC = segue.destinationViewController as? NoteDetailViewController {
            yourVC.delegate = self
        }
    }
}