Question

这是一个非常令人困惑的问题，所以我会尽力解释它。

我有视图控制器A，B，C，D和E

我不确定我是否说得对，但重新说明一下，E需要与A交谈，但A和E之间没有设置委托的区别。

A＆gt; B> C> D> E>甲

有人告诉我，当你在swift中使用代理来访问视图控制器之间的数据时，你必须有很多东西：

为对象B定义委托协议。
为对象B提供可选的委托变量。这个变量应该很弱。
当有趣的事情时，让对象B向其委托发送消息发生，例如用户按下取消或完成按钮，或者当它需要一条信息。
使对象A符合委托协议。应该把它的名字该类协议在其类行中实现协议中的方法。
告诉对象B对象A现在是其委托。

我一直在使用prepapreforsegue在视图控制器之间传递一个对象，因为它们从一个对象导航到下一个对象，在它们继续执行prepareforsegue方法时添加它。

在最终视图控制器上，我有一些协议方法可以在第一个视图控制器上执行，但是因为最后一个视图控制器从一个不同的视图控制器中分离出来。问题是它应该在第一个视图控制器上执行这些方法。如果没有第一个视图控制器能够告诉最后一个视图控制器它是segue，它怎么能达到它。

这是一些简单的代码，向您展示我的问题和我的意思。

首先：

import UIKit

class FirstViewController: UITableViewController, LastViewControllerDelegate {

var entry: EntryItem!

override func viewDidLoad() {
    super.viewDidLoad()
    entry = EntryItem()
    // Uncomment the following line to preserve selection between presentations
    // self.clearsSelectionOnViewWillAppear = false

    // Uncomment the following line to display an Edit button in the navigation bar for this view controller.
    // self.navigationItem.rightBarButtonItem = self.editButtonItem()
}

...

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {

    //here's where I access the next view controller and set controller.entry and controller.delegate
    let controller = segue.destinationViewController as NextViewController
    controller.entry = entry
}

func lastViewControllerDidCancel(controller: LastViewController, didNotFinishAddingEntry draftentry: EntryItem){
    //this is where I wanna do something
    dismissViewControllerAnimated(true, completion: nil)
}
func lastViewController(controller: LastViewController, didFinishAddingEntry finalentry: EntryItem){
    //this is where I wanna do something
    dismissViewControllerAnimated(true, completion: nil)
}
}

下一步：

import UIKit


class Next1ViewController: UITableViewController, LastViewControllerDelegate {

var entry: EntryItem!

override func viewDidLoad() {
    super.viewDidLoad()

    // Uncomment the following line to preserve selection between presentations
    // self.clearsSelectionOnViewWillAppear = false

    // Uncomment the following line to display an Edit button in the navigation bar for this view controller.
    // self.navigationItem.rightBarButtonItem = self.editButtonItem()
}

...

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    //here's where I access the next view controller and set controller.entry and controller.delegate
    let controller = segue.destinationViewController as Next2ViewController
    controller.entry = entry
}


}

下一步2：

import UIKit


class Next2ViewController: UITableViewController, LastViewControllerDelegate {

    var entry: EntryItem!

    override func viewDidLoad() {
        super.viewDidLoad()

        // Uncomment the following line to preserve selection between presentations
        // self.clearsSelectionOnViewWillAppear = false

        // Uncomment the following line to display an Edit button in the navigation bar for this view controller.
        // self.navigationItem.rightBarButtonItem = self.editButtonItem()
    }

    ...

    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        //here's where I access the next view controller and set controller.entry and controller.delegate
        let controller = segue.destinationViewController as LastViewController
        controller.entry = entry
        controller.delegate = ???? //Not self, but needs to be the first one.
    }


}

最后：

import UIKit

protocol LastViewControllerDelegate: class {
    func lastViewControllerDidCancel(controller: LastViewController, didNotFinishAddingEntry draftentry: EntryItem)
    func lastViewController(controller: LastViewController, didFinishAddingEntry finalentry: EntryItem)
}

class LastViewController: UITableViewController {

weak var delegate: LastViewControllerDelegate?
var entry: EntryItem!

override func viewDidLoad() {
    super.viewDidLoad()

    // Uncomment the following line to preserve selection between presentations
    // self.clearsSelectionOnViewWillAppear = false

    // Uncomment the following line to display an Edit button in the navigation bar for this view controller.
    // self.navigationItem.rightBarButtonItem = self.editButtonItem()
}

...


@IBAction func cancel(){
    delegate?.lastViewControllerDidCancel(self, didNotFinishAddingEntry: entry)
}

@IBAction func done(){
    //do some final additions to entry object
    delegate?.lastViewController(self, didFinishAddingEntry: entry)
}

}

Answer 1

难道你不能让你的第一个视图控制器符合所有委托协议（或者，可能会制作一个委托协议，否则你会遇到转换问题），然后不要这样做：

controller.delegate = self

只做

controller.delegate = self.delegate

或者，如果您删除了几个步骤，则使用通知通常比委派更好。如果介入视图控制器除了转发它之外没有委托的目的，您应该使用通知。

Swift：我的代理协议方法需要在另一个视图控制器上执行

1 个答案: