在for循环中添加整数并打印总数

Question

我正在遍历整数对象并希望将每个整数添加到整数变量，然后当for循环完成时，打印总数。是否有捷径可寻？现在，我可以检索这些对象并单独打印它们，但每次总打印数为0。 请参阅下面的代码。这是一个用Swift和Parse编写的应用程序作为后端。 有帮助，谢谢！

var itemsArray = [Int]() 
let followingUserItemsQuery = PFUser.query() 
followingUserItemsQuery?.whereKey("objectId", equalTo: (PFUser.currentUser()?.objectId!)!) 
followingUserItemsQuery?.findObjectsInBackgroundWithBlock({ (objects: [PFObject]?, error) in 
       if let objects = objects { 
       for object in objects { 
       let followingUsersArray = (object["following"] as! [String]) 
       // Get number of listed items of following users with PFUser query for their total objects 
        for followingUser in followingUsersArray { 
         print(followingUser) 
         let query = PFUser.query() 
         query?.whereKey("objectId", equalTo: followingUser) 
         //Get each user's listedItems count then append to a higher-level integer variable 
         query?.getFirstObjectInBackgroundWithBlock({ (object, error) in 
          itemsArray.append(object!["listedItems"] as! Int) 
         }) 
        } 
       } 
      } 
      let itemsSum = itemsArray.reduce(0, combine: +) 
      print(itemsSum) 
      self.followingUsersAddedItems.text = String("Your followers listed "+String(itemsSum)+" items") 

Answer 1

试试这个：

var count = 0 
... 
for followingUser in followingUsersArray { 
    count += object!["listedItems"] as! Int 
} 

Answer 2

您的代码，以减少/组合Int值是正确的。问题是它在任何嵌套异步Parse查询完成并执行它们的回调之前运行。所以在运行时，itemsArray仍然是空的。您将需要重新设计代码，以便之后itemsSum仅计算所有各种嵌套的分析查询都已完成。