Question

我有firebase实时数据库。我有标签和用户。当有人点击按钮时我希望从标签获得价值，增加它并更新新值。但我有观察者，我不能用这段代码获得更新的价值：

DataService.dataService.TAG_REF.observe(.value, with: { (snapshot) in
    self.tags = []

    if let snapshots = snapshot.children.allObjects as? [FIRDataSnapshot] {
        for snap in snapshots {
            if let postDictionary = snap.value as? Dictionary<String, AnyObject> {
                let key = snap.key
                let tag = Tag(key: key, dictionary: postDictionary)
                self.tags.insert(tag, at: 0)
            }
        }
    }
    self.dashCollectionView.reloadData()
    }) { (error) in
        print(error.localizedDescription)
}

当我点击按钮时：

if sender.image(for: .normal) == UIImage(named: "like") {
    DataService.dataService.TAG_REF.child(selectedTag.tagKey).observeSingleEvent(of: .value, with: { snapshot in
        let totalLikeSnap = snapshot.value as! Dictionary<String, AnyObject>
        var totalLike = totalLikeSnap["like"] as! Int
        totalLike = totalLike + 1
        DataService.dataService.TAG_REF.child(selectedTag.tagKey).child("like").setValue(totalLike)    
    })

    let likedTags = DataService.dataService.CURRENT_USER_REF.child("likedTags").child(selectedTag.tagKey)
    likedTags.setValue(["time": "getcurrenttimelater"])

    sender.setImage(UIImage(named: "liked"), for: .normal)
    sender.setTitle(String(selectedTag.tagLikes), for: .normal)

    self.dashCollectionView.reloadData()
} else {
    print("already liked")
}

但它并没有增加。如果有人帮我更新数据，我会很高兴。

tags {
    -bB1231e23a24 {
       comment: 0
       image: "1"
       like: 1
    }
}

Answer 1

首先，改变你在数据库中增加喜欢的方式。

func updateTotalNoOfPost(completionBlock : (() -> Void)){

 let prntRef = FIRDatabase.database().reference().child("tags/\(selectedTag.tagKey)")

 prntRef.child("like").runTransactionBlock({ (noOfLikes) -> FIRTransactionResult in
    if let totalLikes = noOfLikes.value as? Int{

        noOfLikes.value = totalLikes + 1
        return FIRTransactionResult.successWithValue(noOfLikes)
    }else{

        return FIRTransactionResult.successWithValue(noOfLikes)

        }
      }, andCompletionBlock: {(error,completion,snap) in

            print(error?.localizedDescription)
            print(completion)
            print(snap)
        if !completion {

            print("The value wasn't able to Update")
            }else{

            completionBlock()
        }
   })
}

必须有一个数组，您必须在其中保存您的collectionView数据源的noOfLike。更新数据库时，还要更新collectionView数据源。

当您的用户点击按钮时，在按钮功能中： -

updateTotalNoOfLikes{
   print("Value incremented!")

   // Here add the value to your collectionView datasource
    //And then call collectionView.reloadData()
    }

Firebase实时数据库获得价值和增量

1 个答案: