如何從可重用標題按鈕調用collectionView.reloadData（）？

Question

我在可重用的標題視圖中有一個按鈕，用於刪除爲集合視圖和標題提供數據的數組中的信息。我希望它也能夠執行collectionView.reloadData()。

問題是我不能從標題按鈕調用collectionView.reloadData()，因爲它不能將collectionView識別爲變量。如果我打電話Builds().collectionView.reloadData()（構建是視圖控制器），該應用程序崩潰，因爲它說它發現零，而解包可選。我知道，簡單地叫collectionView.reloadData()不是問題，因爲我有collectionView.reloadData()調用viewDidAppear()，並且這不會導致崩潰。

這是怎麼回事？如何在按鈕刪除數據後讓我的collectionView重新加載數據？

參考：

可重複使用的部首：

import UIKit 

class BuildsHeader: UICollectionReusableView { 

@IBOutlet weak var headerLabel: UILabel! 

@IBOutlet weak var deleteBuildButton: UIButton! 

@IBAction func deleteBuildButton(sender: UIButton) { 

    for hero in heroes{ if hero.hero.name == heroForDetails.hero.name { 
     hero.builds.removeAtIndex(sender.tag) 
     heroForDetails = hero 
     }} 

    saveToDefaults(userProfile) 
    //Builds().collectionBuild.reloadData() runs just fine without this line 
} 
} 

的ViewController：

import UIKit 

class Builds: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout { 

@IBOutlet weak var collectionBuild: UICollectionView! 

override func viewDidLoad() { 
    super.viewDidLoad() 

    collectionBuild.delegate = self 
    collectionBuild.dataSource = self 

} 

override func didReceiveMemoryWarning() { 
    super.didReceiveMemoryWarning() 
    // Dispose of any resources that can be recreated. 
} 

override func viewDidAppear(animated: Bool) { 
    collectionBuild.reloadData() 
} 

func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell { 

     if let cell = collectionView.dequeueReusableCellWithReuseIdentifier("BuildCell", forIndexPath: indexPath) as? TalentsCell { 

      let build = heroForDetails.builds[indexPath.section] 

      switch (indexPath.row) { 

      case 0: 
       cell.configureCell(build["1"]! as! Talent) 
      case 1: 
       cell.configureCell(build["4"]! as! Talent) 
      case 2: 
       cell.configureCell(build["7"]! as! Talent) 
      case 3: 
       cell.configureCell(build["10"]! as! Talent) 
      case 4: 
       cell.configureCell(build["13"]! as! Talent) 
      case 5: 
       cell.configureCell(build["16"]! as! Talent) 
      case 6: 
       cell.configureCell(build["20"]! as! Talent) 
      default: 
       cell.configureCell(build["1"]! as! Talent) 

      } 

      return cell 

    } 
    return UICollectionViewCell() 
} 

func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) { 

} 

func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int { 
    return 7 
} 

func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int { 
    return heroForDetails.builds.count 
} 

func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize { 
    return CGSizeMake(50,50) 
} 

func collectionView(collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, atIndexPath indexPath: NSIndexPath) -> UICollectionReusableView { 

    let header = collectionView.dequeueReusableSupplementaryViewOfKind(UICollectionElementKindSectionHeader, withReuseIdentifier: "BuildsHeader", forIndexPath: indexPath) as! BuildsHeader 

    var buildDict = heroForDetails.builds[indexPath.section] 
    header.headerLabel.text = buildDict["name"] as! String 
    header.deleteBuildButton.tag = indexPath.section 
    return header 

} 
} 

Answer 1

可以實現與代表團。

1. 創建一個協議
2. 內BuildsHeader爲委託創建一個變量
3. 呼叫在deleteBuildButton功能

現在的委託方法BuildsHeader的代碼應該是這樣的：

import UIKit 

//**** The Protocol **** 
protocol BuildsHeaderDelegate { 
    func updateCollectionView() 
} 

class BuildsHeader: UICollectionReusableView { 

    //**** Variable for the delegate **** 
    var delegate: BuildsHeaderDelegate? 

    @IBOutlet weak var headerLabel: UILabel! 

    @IBOutlet weak var deleteBuildButton: UIButton! 

    @IBAction func deleteBuildButton(sender: UIButton) { 

     for hero in heroes{ if hero.hero.name == heroForDetails.hero.name { 
      hero.builds.removeAtIndex(sender.tag) 
      heroForDetails = hero 
      }} 

     saveToDefaults(userProfile) 
     //**** Call the delegate method **** 
     self.delegate?.updateCollectionView() 
    } 
} 

1. 在您的收藏鑑於viewForSupplementaryElementOfKind方法配置頭的delegate財產，像這樣：

   let header = collectionView.dequeueReusableSupplementaryViewOfKind(UICollectionElementKindSectionHeader, withReuseIdentifier: "BuildsHeader", forIndexPath: indexPath) as! BuildsHeader 
   //**** Set this view controller to be the header's delegate **** 
   header.delegate = self 
   // rest of header setup 
   

2. 充分利用Builds ViewController中確認到BuildsHeaderDelegate：

   class Builds: UIViewController, BuildsHeaderDelegate, UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout { 
   

3. 實施BuildsHeaderDelegate的委託方法在Builds視圖控制器中。您可以在viewForSupplementaryElementOfKind方法後，把這個權利：

   func updateCollectionView() { 
       //**** reload the collectionView **** 
       self.collectionBuild.reloadData() 
   } 
   

Answer 2

使用d elegate要調用的方法：

protocol BuildsHeaderDelegate(){ 
    func reloadCollectionView() 
} 

class BuildsHeader: UICollectionReusableView { 

    var delegate:BuildsHeaderDelegate! 

    @IBOutlet weak var headerLabel: UILabel! 
    @IBOutlet weak var deleteBuildButton: UIButton! 

    @IBAction func deleteBuildButton(sender: UIButton) { 

     for hero in heroes{ if hero.hero.name == heroForDetails.hero.name { 
      hero.builds.removeAtIndex(sender.tag) 
      heroForDetails = hero 
      }} 

     saveToDefaults(userProfile) 

     //##Call delegate method## 
     delegate.reloadCollectionView() 
    } 

} 

順應代表在視圖控制器，併爲其分配：

class Builds: UIViewController,delegate:BuildsHeaderDelegate , UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout { 

    @IBOutlet weak var collectionBuild: UICollectionView! 

    override func viewDidLoad() { 
     super.viewDidLoad() 

     collectionBuild.delegate = self 
     collectionBuild.dataSource = self 

    } 

    func reloadCollectionView() { 
     collectionBuild.reloadData() 
    } 

    func collectionView(collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, atIndexPath indexPath: NSIndexPath) -> UICollectionReusableView { 

     let header = collectionView.dequeueReusableSupplementaryViewOfKind(UICollectionElementKindSectionHeader, withReuseIdentifier: "BuildsHeader", forIndexPath: indexPath) as! BuildsHeader 

     //##Assign Delegate## 
     header.delegate = self 

     var buildDict = heroForDetails.builds[indexPath.section] 
     header.headerLabel.text = buildDict["name"] as! String 
     header.deleteBuildButton.tag = indexPath.section 
     return header 

    } 

}