如何在 UICollectionViewLayout 和 UIViewController 之间传递数据 [英] how to pass data between UICollectionViewLayout and UIViewController

问题描述

我需要基于对 api 的 http 调用创建自定义布局.根据循环中 api 的结果，我将从 CollectionView 填充一个数组

在 CustomLayout 中，我需要使用这个数组才能在每一行中正确绘制细节.在 collectionView 中，我在将数据添加到数组后使用重新加载数据

谢谢你

代码:

class epgViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource{var 事件 = [事件]()@IBOutlet 弱变量 collectionView:UICollectionView！//另一个初始化...//====== 加载事件 ==============func get_events() {//http api调用//作为循环的结果，我将数据附加到 Events()self.events.append(newEvent)//重新加载集合视图数据self.collectionView.reloadData()}}/////////////布局////////类 customCollectionViewLayout:UICollectionViewLayout {//准备布局覆盖 func prepareLayout() {对于 0...collectionView 中的部分！.numberOfSections()-1 {如何从 collectionView 访问数组事件[i] ????}}}

解决方案

我不完全确定我了解您的情况，但我会提供两种在您的应用程序中进行通信的方法.

使用 NSNotificationCenter

在需要触发事件的控制器的viewDidLoad中添加一个观察者:

NSNotificationCenter.defaultCenter().addObserver(self, selector: "remoteRefresh:", name:"remoteRefreshID", object: nil)

在同一个控制器中添加一个与我们的选择器名称相同的观察者，在上面的例子中是remoteRefresh".

func remoteRefresh(notification: NSNotification) {//做东西}

然后在您的另一个控制器中可以发布消息并且您的 remoteRefresh 操作将运行:

NSNotificationCenter.defaultCenter().postNotificationName("remoteRefreshID", object: nil)

有关更多详细信息，我有一个关于 NSNotificationCenter 的两部分教程

协议/委托模式

第二个是协议/委托模式，它有点复杂，但我在这里有一个书面教程:

协议/委托模式

另一种选择

如果您仍有问题，这里有一个选项.您可以声明一个全局结构来保存您的数据，然后将其粘贴到 Playground 中以进行理解.

struct SessionData {静态 var 事件 = [String]()}类 classOne {函数添加值(){SessionData.events.append("一条消息")SessionData.events.append("另一条消息")}}类类二{func getValues() ->[细绳] {返回 SessionData.events}}classOne().addValues()classTwo().getValues()

I need to create a custom layout based on http call to an api. Based on result from api in loop i will populate an array from CollectionView

In CustomLayout I need to use this array in order to draw correctly details in each row. In collectionView I use reload data after the data was added to array

Thank YOu

code:

class epgViewController:  UIViewController,  UICollectionViewDelegate, UICollectionViewDataSource{

    var events     = [Event]()  
      @IBOutlet weak var collectionView: UICollectionView!

      //another initializations
      . . .

       //====== load Events ===============
        func get_events() {

            //http api call
            //as result in loop i append data to Events()
              self.events.append(newEvent)
        //reload collection view data    
        self.collectionView.reloadData()
       }
    }
//////////
/// LAyout
////////
     class customCollectionViewLayout: UICollectionViewLayout {

     //prepare layout  
     override func prepareLayout() {
        for section in 0...collectionView!.numberOfSections()-1 {
            how to access array from collectionView
            Events[i] ????

      }
     }  
    }

解决方案

I'm not entirely sure I understand your situation, but I'll provide two methods for communication within your application.

Using NSNotificationCenter

Add an observer In the viewDidLoad of the controller that needs an event fired:

NSNotificationCenter.defaultCenter().addObserver(self, selector: "remoteRefresh:", name:"remoteRefreshID", object: nil)

In that same controller add an observer with a name the same as our selector, in the above example "remoteRefresh".

func remoteRefresh(notification: NSNotification) {
    // do stuff
}

Then in your other controller can post messages and your remoteRefresh action will run:

NSNotificationCenter.defaultCenter().postNotificationName("remoteRefreshID", object: nil)

for more details I have a two part tutorial on NSNotificationCenter

Protocol / Delegate pattern

The second is the Protocol / Delegate pattern which is a bit more involved but I have a written tutorial here:

protocol / delegate pattern

Another Option

Here's an option if you're still having issues. You could declare a global struct to hold your data, paste this into a playground to understand.

struct SessionData {

    static var events = [String]()
}


class classOne {

    func addValues() {

        SessionData.events.append("a message")
        SessionData.events.append("another message")
    }
}


class classTwo {

    func getValues() -> [String] {

        return SessionData.events

    }

}

classOne().addValues()
classTwo().getValues()

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