單獨的UICollectionView數據源和委托未被調用

Question

我正在嘗試為我的UICollectionView DataSource和Delegate使用單獨的類，但是沒有調用這些方法。

視圖層次結構如下：

(Root VC)        -> (Current Screen) -> (Current Page)       -> (CollectionView in question)
UIViewController -> UIViewController -> UIPageViewController -> UICollectionView

這是Current Screen VC的類。

import UIKit

class FooController: UIViewController {
  // PageViewController
  let pageController = UIPageViewController(/*...*/)
  let pageOne = UIViewController()
  let pageTwo = UIViewController()

  override func loadView() {
    super.loadView()
    // Setup Stuff
    bootstrapPageOne()
  }

  func bootstrapPageOne() {
    // Do PageView Stuff
    bootstrapBars()
  }

  func bootstrapBars() {
    // Everything is set up when this function is called.

    let collectionViewFlowLayout = UICollectionViewFlowLayout()
    let cellSize : CGFloat = 60

    let collectionViewWidth = view.bounds.width - 20 * 2 //CGFloat(barsCount.count) * cellSize
    let collectionViewHeight = cellSize
    let collectionViewFrame : CGRect = CGRect(x: 20, y: view.bounds.height - (60 + view.layer.cornerRadius), width: collectionViewWidth, height: collectionViewHeight)

    let barCollectionView = UICollectionView(frame: collectionViewFrame, collectionViewLayout: collectionViewFlowLayout)
    let fooBarHandler = FooBarCollectionHandler()
    barCollectionView.delegate = fooBarHandler
    barCollectionView.dataSource = fooBarHandler
    barCollectionView.registerClass(UICollectionViewCell.self, forCellWithReuseIdentifier: "barCellIdentifier")
    barCollectionView.backgroundColor = UIColor.blueColor()

    pageOne.view.addSubview(barCollectionView)
  }
}

這是CollectionView DataSource和Delegate的類

import UIKit

class FooBarCollectionHandler: NSObject, UICollectionViewDelegateFlowLayout, UICollectionViewDataSource {
  let settings = SettingsHandler.sharedSettings

  func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
    debugPrint(#function)
    return 1
  }

  func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
    debugPrint(#function)
    let cell = collectionView.dequeueReusableCellWithReuseIdentifier("barCellIdentifier", forIndexPath: indexPath)

    return cell
  }

  func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    debugPrint(#function)
    return settings.bars.count // 5
  }

  func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
    debugPrint(#function)
    return CGSizeMake(40,40)
  }
}

// MARK: - Touch handling
extension FooBarCollectionHandler {
  func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
    debugPrint(#function)
    debugPrint(indexPath.row)
  }
}

使用當前配置，不會調用任何委托/數據源方法。 我可以調用barCollectionView.numberOfSections()或barCollectionView.numberOfItemsInSection(_:) ，它將調用並返回，但它們不會自動調用。

注意： UICollectionView呈現正常，但單元格沒有。

Answer 1

foobarhandler有一個弱參考作為代表。 因此，當您離開bootstrapBars的范圍時，它將被釋放。

將其存儲在本地以保留參考：

var myDelegate : FooBarCollectionHandler?

func bootstrapBars() {
    //your stuff
    myDelegate = FooBarCollectionHandler()
    barCollectionView.delegate = myDelegate
    barCollectionView.dataSource = myDelegate

}