问题描述
我来自AS3的背景，因此可能更容易向我展示我要使用AS3进行的操作.我有一个UIViewController(root)，里面有一个ContainerView.我的印象是容器视图的UIViewController是UIViewController(root)的子级.我想在子视图控制器(容器视图)上按下一个按钮，然后将该事件冒泡到父视图(根UIViewController).在AS3中，我会遇到这样的情况
I'm coming from as AS3 background so it might be easier for me to show you what I'm trying to do with AS3. I have a UIViewController(root) and inside that I have a ContainerView. I am under the impression that the container view's UIViewController is a child of the UIViewController(root). I would like a button to be pressed on the child view controller (container view) and bubble that event up to the parent(root UIViewController). In AS3 I would have something like this
根类创建子类
var childClass = new ChildClass()
childClass.addEventListener("buttonWasPressed", callThisFunction);
private function callThisFunciton(e:Event):void
{
// move the child view
TweenLite.to(childClass,1,{x:100});
}
在子类中，我有一个按钮函数，该函数将部署此事件并将其扩展到父级.
And in the Child Class I have a button function that would deploy this event that would bubble up to the parent.
dispatchEvent(new Event("buttonWasPressed", true));
我不确定该怎么做是让根VC监听该事件.因为我使用的是containerView，所以我不确定如何为该子VC设置出口，并听听该子在做什么.我可以控制从IB到VC的拖动，但这只是为代表容器视图的UIView创建了一个出口.当我打印一些文本时，我可以看到在父VC之前先实例化了子视图控制器.
What I'm not sure how to do is get the root VC listening for that event. Because I'm using a containerView I'm not sure how to set up an outlet to that child VC and listen to things that the child is doing. I can control drag from the IB to the VC, but that just created an outlet for a UIView that represents the container view. When I println some text, I can see that the child view controller is being instantiated first before the parent VC.
我发现我认为此帖子指向了正确的方向. https://craiggrummitt.wordpress.com/2014/07/14/communication-between-objects-in-objective-c-and-swift-compared-with-actionscript-part-5/
I found this post that I think is pointing in the right direction.https://craiggrummitt.wordpress.com/2014/07/14/communication-between-objects-in-objective-c-and-swift-compared-with-actionscript-part-5/
但是我遇到了一个错误，很可能是因为我不确定如何在容器视图内建立从父VC到子VC的连接.我环顾四周，似乎找不到关于该主题的太多信息.
But I'm getting an error, most likely because I'm not sure how to make the connection from parent VC to child VC that's inside the container view. I have looked around and I can't seem to find much information on the topic.
感谢您的帮助！
推荐答案
有两种方法:
1)使用委托协议(推荐)
a)在您的孩子中，创建一个委托协议，并在将保留委托的子VC上创建一个可选属性.
a) In your child, create a delegate protocol, and an optional property on the child VC that will hold the delegate.
protocol ChildViewControllerDelegate {
}
class ChildViewController: UIViewController {
var delegate:ChildViewControllerDelegate?
}
b)在委托协议中，创建一个将在按下按钮时调用的方法，并在子代中实现一个buttonWasPressed()方法，该子方法在委托上调用此方法. (您需要将此方法与情节提要中的按钮关联起来)
b) In the delegate protocol create a method that will be called when the button was pressed, and implement a buttonWasPressed() method in the child that calls this method on the delegate. (You'll want to connect this method up with a button in the storyboard)
protocol ChildViewControllerDelegate {
func childViewControllerDidPressButton(childViewController:ChildViewController)
}
class ChildViewController: UIViewController {
var delegate:ChildViewControllerDelegate?
@IBOutlet weak var button: UIButton!
@IBAction func buttonWasPressed(sender: AnyObject) {
self.delegate?.childViewControllerDidPressButton(self)
}
}
c)使您的父视图控制器符合子协议
c) Make your parent view controller conform to the child protocol
class ParentViewController: UIViewController, ChildViewControllerDelegate {
func childViewControllerDidPressButton(childViewController: ChildViewController) {
// Do fun handling of child button presses!
}
}
c)当孩子被嵌入父母中时，会运行一种特殊的segue，称为嵌入segue.您可以在情节提要中看到它-这是将孩子与父母联系起来的那一行:
c) When the child is embedded in the parent a special kind of segue is run called an embed segue. You can see it in the storyboard - it’s the line that connects the child to the parent:
在情节提要中为该序列添加标识符:
Add an identifier to that segue in the storyboard:
以及在父视图控制器中为其设置的常量:
And a constant for it in the parent view controller:
struct Constants {
static let embedSegue = "embedSegue"
}
class ParentViewController: UIViewController, ChildViewControllerDelegate {
func childViewControllerDidPressButton(childViewController: ChildViewController) {
// Do fun handling of child button presses!
}
}
d)然后在父视图控制器中，覆盖prepareForSegue()方法，并检查segue.identifier是否与您设置为标识符的内容匹配.如果是这样，则可以通过segue.destinationViewController获得对子视图控制器的引用.将此作为您的子视图控制器，然后可以将父级设置为其委托:
d) Then in the parent view controller, override the prepareForSegue() method and check if segue.identifier matches what you had set as the identifier. If it does, then you can get a reference to the child view controller through segue.destinationViewController. Cast this as your child view controller, then you can set the parent to be its delegate:
struct Constants {
static let embedSegue = "embedSegue"
}
class ParentViewController: UIViewController, ChildViewControllerDelegate {
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == Constants.embedSegue {
let childViewController = segue.destinationViewController as ChildViewController
childViewController.delegate = self
}
}
func childViewControllerDidPressButton(childViewController: ChildViewController) {
// Do fun handling of child button presses!
}
}
e)赢！
2)使用NSNotification和NSNotificationCenter
您可以将其视为与ActionScript事件类似，但是它们不会像AS这样在视图层次结构中自动冒泡.而是通过NSNotificationCenter在全局范围内分发通知.我更喜欢仅在有多个对象需要侦听一个特定事件时使用它.
You can think of these as similar to ActionScript events, however they don’t automatically bubble up through the view hierarchy like AS. Instead notifications are dispatched globally through NSNotificationCenter. I prefer to only use this when there are multiple objects that need to listen for one particular event.
您可以在此处找到有关NSNotification和NSNotificationCenter的更多信息: https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Classes/NSNotificationCenter_Class/
You can find more information about NSNotification and NSNotificationCenter here: https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Classes/NSNotificationCenter_Class/
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