Fetch data from multiple node in Firebase in Swift - swift

Question

I built my app to have news feed like Facebook. My problem is that I don't know how to fetch child images in Post and show it in a collectionView. Please show me how to do it. Appreciate any help.
Here is the db structure:
Posts
d7j3bWMluvZ6VH4tctQ7B63dU4u1:
20181112101928:
avatar: "https://platform-lookaside.fbsbx.com/platform/p..."
content: "Funny image"
images:
-LR4vaEIggkGekc-5ZME:
"https://firebasestorage.googleapis.com/v0/b/hon..."
-LR4vaENC-IsePibQYxY:
"https://firebasestorage.googleapis.com/v0/b/hon..."
name: "Thành Trung"
time: 1541992768776.3628
type: "Funny"
Here is my code:
func getDataFromPostFirebase() {
let getPostData = databaseReference.child("Posts")
getPostData.observe(.childAdded) { (snapshot) in
getPostData.child(snapshot.key).observe(.childAdded, with: { (snapshot1) in
getPostData.child(snapshot.key).child(snapshot1.key).observe(.value, with: { (snapshot2) in
self.arrayImageUrl = [String]()
if let dict = snapshot2.value as? [String : Any] {
guard let avatar = dict["avatar"] as? String else {return}
guard let content = dict["content"] as? String else {return}
guard let name = dict["name"] as? String else {return}
guard let time = dict["time"] as? Double else {return}
guard let type = dict["type"] as? String else {return}
if let images = dict["images"] as? [String : String] {
for image in images.values {
self.arrayImageUrl.append(image)
}
let newPost = Post(avatarString: avatar, contentString: content, nameString: name, timeDouble: time, typeString: type)
self.arrayPost.append(newPost)
DispatchQueue.main.async {
self.feedTableView.reloadData()
}
} else {
let newPost = Post(avatarString: avatar, contentString: content, nameString: name, timeDouble: time, typeString: type)
self.arrayPost.append(newPost)
DispatchQueue.main.async {
self.feedTableView.reloadData()
}
}
}
})
})
}
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return arrayImageUrl.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "collectionViewCell", for: indexPath) as! TrangChu_CollectionViewCell
cell.imgContent.layer.cornerRadius = CGFloat(8)
cell.imgContent.clipsToBounds = true
cell.imgContent.layer.borderWidth = 2
cell.imgContent.layer.borderColor = #colorLiteral(red: 0.4756349325, green: 0.4756467342, blue: 0.4756404161, alpha: 1)
let url = URL(string: arrayImageUrl[indexPath.row])
cell.imgContent.sd_setImage(with: url, completed: nil)
return cell
}
Model object
import Foundation
class Post {
var avatar : String
var content : String
var images : [String]?
var name : String
var time : Double
var type : String
init(avatarString : String, contentString : String, nameString : String, timeDouble : Double, typeString : String) {
avatar = avatarString
content = contentString
// images = imagesString
name = nameString
time = timeDouble
type = typeString
}
}

Answer 1

As what I've said your db is not well structured. I suggest you re structure it like this.
Posts
d7j3bWMluvZ6VH4tctQ7B63dU4u1:
avatar: "https://platform-lookaside.fbsbx.com/platform/p..."
content: "Funny image"
images:
-LR4vaEIggkGekc-5ZME: "https://firebasestorage.googleapis.com/v0/b/hon..."
-LR4vaENC-IsePibQYxY: "https://firebasestorage.googleapis.com/v0/b/hon..."
name: "Thành Trung"
time: 1541992768776.3628
type: "Funny"
timestamp: 1540276959924
I removed the timestamp node and transferred it along the children node. Now you can fetch the posts with this.
ref.child("Posts").observe(.childAdded) { (snapshot) in
var post = Post()
let val = snapshot.value as! [String: Any]
post.name = val["name"] as? String
self.ref.child("Posts").child(snapshot.key).child("images").observeSingleEvent(of: .value, with: { (snap) in
post.imagesString = [String]()
for image in snap.children.allObjects as! [DataSnapshot] {
post.imagesString?.append(image.value as! String)
print("images \(image.value)")
}
list.append(post)
print("post \(post)")
})
If you want to order the posts you can achieve it using queryOrderedByChild("timestamp")

Answer 2

Add this to access your images:
guard let images = dict["images"] as? [[String: Any]] { return }
let imagesString: [String] = []
for imageDict in images {
for key in imageDict.keys {
if let imageName = imageDict[key] as? String else {
// here you access your image as you want
imagesString.append(imageName)
}
}
}
Then when creating the post object you use imagesString that we created:
let newPost = Post(avatarString: avatar, contentString: content, imagesString: imagesString, nameString: name, timeDouble: time, typeString: type)

Answer 3

You can fetch the images values using this
ref.child("Posts").observe(.childAdded) { (snapshot) in
self.ref.child("Posts").child(snapshot.key).observe(.childAdded, with: { (snapshot1) in
self.ref.child("Posts").child(snapshot.key).child(snapshot1.key).child("images").observe(.childAdded, with: { (snap) in
let post = new Post()
for rest in snap.children.allObjects as! [DataSnapshot] {
//append images
post.imagesString.append(rest.value)
}
post.avatarString = snapshot1.value["avatar"] as? String
...
})
})
I suggest you change the structure of your db because its nested. Refer here