使用数组数据更新 TableView

Question

I have a PFQuery in viewDidLoad called in getUserPicPostData . The output shows there are 3 images in the array count.

ViewdidLoad:

func getUserPicPostData() {
    let query = PFQuery(className: "PicPost")
    query.whereKey("Username", equalTo: usernameSelected)
    query.findObjectsInBackground(block: { (objects: [PFObject]?,error: Error?) in
        if let objects = objects {
            for object in objects {
                self.picLikeArray.append(object["UserLikes"] as! Int)
                self.picTimeArray.append(object["UserTime"] as! String)
                self.picObjectIdArray.append(object.objectId!)

                let userImageFile = object["ImageFile"] as? PFFileObject

                userImageFile?.getDataInBackground(block: { (imageData: Data?, error: Error?) in
                    if error == nil {
                        self.picPostArray.append(UIImage(data: imageData!)!) 
                        print(self.picPostArray.count)
                    } 
                    else {
                        print(error)
                    }
                })
            } 
        }
    })
}

Then I want to tell my cells to take the inputs of the imageArray. PicPostArray is now nil??

cellForRowAtIndexPath:

print(picPostArray)
cell.imageView1.imageView!.image = picPostArray[0]
cell.imageView2.imageView!.image = picPostArray[1]
cell.imageView3.imageView!.image = picPostArray[2]

Answer 1

When you reload the table, your picPostArray is nil because it's not setted yet. This is due to your asynchronous query.findObjectsInBackground . To solve this, you can reload the table only when picPostArray is setted:

var picPostArray: [UIImage] = [] {
    didSet {
        yourTableView.reloadData()
    }
}

Answer 2

Just reload the tableView after adding the image on the list.

picPostArray initialization will be

var picPostArray:[UIImage] = [] // picPostArray not nil 

And then reload the tableView when the image is set on the array.

self.picPostArray.append(UIImage(data: imageData!)!) 
self.tableView.reloadData()

Due to an asynchronous request, you need to reload the tableView.

Hope this will solve this issue.