如何使uicollectionview在从Firebase接收数据后重新加载?
问题描述:
我想让一个UI collectionView在它从Firebase接收到数据后重新加载自己。现在只有当我点击刷新按钮时它才能手动工作。如何使uicollectionview在从Firebase接收数据后重新加载?
class MedalsViewController: UICollectionViewController {
var imagesArray = [String]()
var identities = [String]()
var identities2 = [String]() //Creates an empty array
var imagesArrayGreyed = [String]()
var identities3 = [String]()
let databaseRef = FIRDatabase.database().reference()
let userID = FIRAuth.auth()?.currentUser?.uid
override func viewDidLoad() {
super.viewDidLoad()
let userID = FIRAuth.auth()?.currentUser?.uid
let databaseRef = FIRDatabase.database().reference()
databaseRef.child("users").child(userID!).child("medals").observeSingleEventOfType(.Value, withBlock: { (snapshot) in
// Get user medals
self.identities3 = snapshot.value as! [String]
print (self.identities3)
})
imagesArray = ["1", "2", "3"] //Add all the medal images here
identities = ["Shield", "Tie", "Star"] //Add all the identities here
identities2 = ["Shield", "Tie"] //Choose what medals the user has.
imagesArrayGreyed = ["1Greyed","2Greyed","3Greyed"] //Add all the greyed images here
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
override func viewWillAppear(animated: Bool) {
self.tabBarController?.tabBar.hidden = false
// Attempt at getting medals array from firebase database
}
override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCellWithReuseIdentifier("cell", forIndexPath: indexPath)
let imageView = cell.viewWithTag(1) as! UIImageView
// Identites2 is the medals you currently own, so it'll check back to see if you own the medal and if not a question mark will be displayed.
// Time to check to see if it can update in real time. Check out firebase and try to link it here
// Also see if can add a progress bar to only show for those greyed out medals
// Get ready to edit this to identities3 which is directly taken from firebase database
if (identities3.contains(identities[indexPath.row])) {
imageView.image = UIImage(named: imagesArray[indexPath.row])
}
else {
imageView.image = UIImage(named: imagesArrayGreyed[indexPath.row]) //Set default image not in identities2
}
return cell
}
override func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return imagesArray.count
}
override func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
let vc = identities[indexPath.row]
let viewController = storyboard?.instantiateViewControllerWithIdentifier(vc)
self.navigationController?.pushViewController(viewController!, animated: true)
viewController?.title = self.identities[indexPath.row]
}
// Send a fake medal from the array of identities2
@IBAction func sendFakeMedalandReload(sender: UIBarButtonItem) {
let databaseRef = FIRDatabase.database().reference()
databaseRef.child("users/\(FIRAuth.auth()!.currentUser!.uid)/medals").setValue(identities2)
self.collectionView!.reloadData()
}
}
通过比较两个数组这段代码的含义基本上是显示奖牌用户有(身份和identities3),以确保它们相符,如果不是会变灰不包含在数组中的身份的图像(identities3)
数据在viewDidLoad中作为firebase的快照数据接收。我打算这样做,使得每次调用viewWillAppear时,collectionView都会重新加载。
我试图在viewDidLoad和viewDidAppear中调用self.collectionView!.reloadData(),但无济于事。我怀疑这可能是数据收到时导致空数组(identities3)被加载的延迟。
答
您需要拨打self.collectionView!.reloadData()
,您需要检索您的数据并将其存入您的DataSource
。
即在你的completionBlock:
你的火力地堡.observeSingleEventOfType
databaseRef.child("users").child(userID!).child("medals").observeSingleEventOfType(.Value, withBlock: { (snapshot) in
// Get user medals
self.identities3 = snapshot.value as! [String]
self.collectionView!.reloadData()
})
它怎么知道当它完成接收数据,然后自动调用? –
谢谢,解决了! –