查看與多個DispatchQueue.main.async凍結使用

Question

查看凍結而數據是獲取並顯示。根據我的理解，fetchBoard()和initUserInfo()不會並行執行。 （僅當加載板時fetchBoard()才加載視圖） 我擔心如果使用DispatchQueue.main.async多次凍結視圖。另外，如何使其順利運行。

class MultipleCardsController2vs2: BaseController, UICollectionViewDataSource , UICollectionViewDelegate { 

override func viewDidLoad() { 
    super.viewDidLoad() 

    let repo = GameRepository() 
    repo.CreateGame(gameID : self.jsonGame.Id , completion: { (jsonGame, err) -> Void in 
     if(err == ErrorCode.NoError){ 
      DispatchQueue.main.async{ 
       self.jsonGame = jsonGame      
      } 
     } 
    }) 

    //These are the two functions I want these 2 to work in parallel 

    self.fetchBoard()   //Function 1 
    self.initUserInfo()   //Function 2 


    collectionView.delegate = self 
    collectionView.dataSource = self 


} // .viewDidLoad 


func fetchBoard(){ 

    let repo = GameRepository() 
    self.sortedBoardArr.reserveCapacity(self.BoardArr.count) 
    let serialQueue = DispatchQueue(label: "serialQueue") 
    let group = DispatchGroup() 
    for board in self.jsonGame.boards{ 
     group.enter() 
     serialQueue.async { 

      repo.GetBoardInfo(gameID: self.jsonGame.Id, boardID: board , completion : {(response , errorCode) -> Void in 

       if errorCode == ErrorCode.NoError{ 
         self.BoardArr.append(response) 
         group.leave() 
        } 
      }) 

      DispatchQueue.main.async{ 

       //Main async - 1 

       group.wait() 
       self.sortArr() 
       self.collectionView.reloadData() 
      } 
     } 
    } 
} 


func sortArr(){ 
    if self.jsonGame.boards.count == self.BoardArr.count{ 

     for board in self.jsonGame.boards{ 
      for boardarr in self.BoardArr{ 
       if boardarr.id == board{ 
        self.sortedBoardArr.append(boardarr) 
       } 
      } 
     } 
    } 

} 

fileprivate func initUserInfo() 
{ 
    DispatchQueue.main.async{ 

       //Main async - 2 

      self.name1.text = self.CurrentUser.UserName 
      self.imgPlayie1.image = UserManager.GetAvatar(user: self.CurrentUser) 
    } 
} 

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int { 
     return self.jsonGame.boards.count 
} 

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell { 
     var cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Round2Cell", for: indexPath) as! Round1vs1cell 

     cell.background.backgroundColor = UIColor(white: 1, alpha: 0.0) 
     cell = self.populateGameCell(game_res, cell , indexPath) 
    return cell 
} 

fileprivate func populateGameCell(_ game_res: Game_Res, _ cell: Round1vs1cell , _ indexPath : IndexPath) -> Round1vs1cell 
{  
    DispatchQueue.main.async { 

     //Main async - 3 

     cell.background.backgroundColor = UIColor(white: 1, alpha: 0.0) 
     cell.word_1.text = game_res.words[0].word 
     cell.color_1.image = UIImage(named: "") 
     cell.life_1.image = UIImage(named: "") 
     cell.name.text = "" 
     cell.op_name.text = game_res.master[index].username 
     cell.timeout_left.image = UIImage(named: "Hourglass.png") 
     cell.round.text = "Round: \(indexPath.row + 1)" 
    } 
    return cell 
} 

} 

尋找順利的工作，而不是凍結視圖。我很樂意與Dispatch合作。歡迎任何幫助。提前致謝。

Answer 1

使用notify()而不是wait()不阻止主線程。

遊樂場例如：

import PlaygroundSupport 

func longRunningTask(completion:() -> Void) { 
    sleep(1) 
    completion() 
} 

func foo(){ 
    let queue = DispatchQueue(label: "myQueue") 
    let group = DispatchGroup() 
    let array = [1, 2, 3] 

    for i in array { 
     print(i) 
     group.enter() 
     queue.async { 
      longRunningTask { 
       print("done \(i)") 
       group.leave() 
      } 
     } 
    } 

    group.notify(queue: DispatchQueue.main) { 
     print("done!") 
    } 
} 

foo() 

PlaygroundPage.current.needsIndefiniteExecution = true 

打印：

1 
2 
3 
done 1 
done 2 
done 3 
done! 

---

附加信息爲什麼你造成了死鎖可以發現in this answer。