I'm using firebase realtime database and it's working fine for some parts of my app. I was going through a tutorial on youtube which populates a collectionView with users. It uses NSDictionary to get the photo URL and username and puts them in the collection view for all users. I deleted some of the users directly in the firebase console, and now have only one user. For some reason it's still pulling the users that I deleted. This is the collectionView file.
import UIKit
import FirebaseDatabase
private let reuseIdentifier = "UserSearchCell"
class UsersCollectionViewController: UICollectionViewController {
var usersDict = NSDictionary?()
var userNamesArray = [String]()
var userImagesArray = [String]()
override func viewDidLoad() {
super.viewDidLoad()
DataService.ds.REF_USERS.observeEventType(.Value, withBlock :{
(snapshot) in
self.usersDict = snapshot.value as? NSDictionary
for(userId,details) in self.usersDict!{
let img = details.objectForKey("profileThumbUrl") as! String
let name = details.objectForKey("username") as! String
self.userImagesArray.append(img)
self.userNamesArray.append(name)
self.collectionView?.reloadData()
}
})
self.collectionView!.registerClass(UICollectionViewCell.self, forCellWithReuseIdentifier: reuseIdentifier)
}
override func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
return 1
}
override func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return self.userImagesArray.count
}
override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifier, forIndexPath: indexPath) as! UserSearchCell
let imageUrl = NSURL(string:userImagesArray[indexPath.row])
let imageData = NSData(contentsOfURL: imageUrl!)
cell.userImage.image = UIImage(data:imageData!)
cell.userName.text = userNamesArray[indexPath.row]
return cell
}
}
Shouldn't this always sync with the database? Where are these deleted users coming from? Also I didn't include the cell code because all it is is the imageView and Label actions being declared. I ran into this problem before but my memory is bad and I don't remember why it was doing it or if I ever solved it.
Okay I figured out the answer to my own question. Apparently the simulator has a problem with firebase and seems to form some sort of cache of firebase data. I tried running it on a phone I had been testing on and it didn't have this cache and everything worked fine. Also I tried running on a different device IN the simulator and it worked fine there too. So I want to leave this up because I think a lot of people may have trouble with Firebase since it's core feature doesn't work well with the IOS simulator.
Related
I'm trying to make an app, in which one of the functions is, that in one viewController, the user can enter some data about a given person (a photo, a name and an answer to a certain question). When pressing the "save new person-button", the user is to be redirected to the previous viewController, which amongst other things holds a tableView.
In this tableView, I want there to be created a new cell for each time the user presses the "save new person-button" in the other viewController. The cell should, of course, hold the person's name (and ideally also a miniature of the photo).
Now, it is important that the data is stored 'internally' - also after exiting a certain viewController or closing the app. Therefore I'm using Realm as a database to store all the data.
I'm very new when it comes to using Realm, so maybe my questions seem stupid. Basically, I think I have been able to make the "Save new person-button" save all the data in the realm database. But when trying to make the button create new cells (which must stay, once created!!) in the previous viewController... All kinds of weird things happen!
What the code underneath shows is my current attempt on passing at least the name through a segue, but that creates several problems: The cells don't stay. If you try to add a new cell, it just overrides the old one. And finally, the PeopleData.count apparently counts the number of letters in the name - and creates fx. 5 identical cells for a 5 letter long name! :D
I'm sure this is not the right way to pass the data ... So what is the best way to present this data? So that the cells stay once created - and so that the user can add several new people/several new cell without overriding the old ones!
Relevant code:
viewController where the user can enter the data:
#IBAction func SaveNewPerson() {
let NewPerson = person()
NewPerson.name = PersonName.text!
NewPerson.answer = PersonAnswer.text!
NewPerson.extraIdentifier = PersonExtraIdentifier.text!
let realm = try! Realm()
try! realm.write {
realm.add(NewPerson)
}
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
// let allPeople = realm.objects(person.self)
let SomePersonName = PersonName.text!
if segue.identifier == "PassingSomeInfo" {
if let vc = segue.destination as? AllPersonsInYourDiary {
vc.PeopleData = SomePersonName
}
}
Viewcontroller with the tableView:
var PeopleData: ""
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return PeopleData.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "Person1", for: indexPath)
cell.textLabel?.text = self.PeopleData
cell.textLabel?.numberOfLines = 0
cell.textLabel?.font = UIFont.preferredFont(forTextStyle: UIFontTextStyle.headline)
return cell
}
Third viewController (used to store all the person-data):
class person: Object {
#objc dynamic var name = ""
#objc dynamic var answer = ""
#objc dynamic var extraIdentifier = "" }
Thanks!
This question is honestly a little to broad. What you are asking for are several things at once. And if I were to write the implementation for you I wouldn't answer your actual question on what you need to do. What I think you are asking is this:
How do I write and retrieve data from realm.
How do I structure my code for passing data between views.
So my recommendation is this.
Don't pass the data with a segue. Create a class that will access Realm and retrieve the data you need for that view. Name it something like Database, Realm or LocalStorage.
In that class add methods for writing to Realm and retrieving from Realm. How to do that you can find in the Realm documentation: https://realm.io/docs/swift/latest/
In your view that needs to display the entries instantiate your Realm class. Some psuedo code to help you on the way:
class ViewController {
fileprivate let database = LocalStorage()
fileprivate var peopleData: [People]()
viewDidLoad() {
super.viewDidLoad()
database.retrieveData(primaryKey: "extraIdentifier", completionHandler: { entries, err in
if err == nil {
self.peopleData = entries
}
})
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return peopleData.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) ->
UITableViewCell {
let person = self.peopleData[indexPath.item]
let cell = tableView.dequeueReusableCell(withIdentifier: "Person1", for: indexPath)
cell.textLabel?.text = person.name
cell.textLabel?.numberOfLines = 0
cell.textLabel?.font = UIFont.preferredFont(forTextStyle: UIFontTextStyle.headline)
return cell
}
}
After you call
try! realm.write {
realm.add(NewPerson)
}
you already saved on realm so you don't have to pass this on the segue you can retrieve from realm on the next view controller by calling
realm.objects(ofType: NewPerson.self)
This will return an array of NewPerson or you can also search just one with your primary key
realm.object(ofType: NewPerson.self, forPrimaryKey: yourKey)
I'm trying to combine a CollectionViewwith a TableView, so fare everything works except one problem, which I cant fix myself.
I have to load some data in the CollectionViews which are sorted with the header of the TableViewCell where the CollectionView is inside. For some reason, every time I start the app, the first three TableViewCells are identical. If I scroll a little bit vertically, they change to the right Data.
But it can also happen that while using it sometimes displays the same Data as in on TableViewCell another TableViewCell, here again the problem is solved if I scroll a little.
I think the problem are the reusableCells but I cant find the mistake myself. I tried to insert a colletionView.reloadData() and to set the cells to nil before reusing, sadly this didn`t work.
My TableViewController
import UIKit
import RealmSwift
import Alamofire
import SwiftyJSON
let myGroupLive = DispatchGroup()
let myGroupCommunity = DispatchGroup()
var channelTitle=""
class HomeVTwoTableViewController: UITableViewController {
var headers = ["LIVE","Channel1", "Channel2", "Channel3", "Channel4", "Channel5", "Channel6"]
override func viewDidLoad() {
super.viewDidLoad()
}
override func viewWillAppear(_ animated: Bool) {
self.navigationController?.navigationBar.isTranslucent = false
DataController().fetchDataLive(mode: "get")
DataController().fetchDataCommunity(mode: "get")
}
//MARK: Custom Tableview Headers
override func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
return headers[section]
}
//MARK: DataSource Methods
override func numberOfSections(in tableView: UITableView) -> Int {
return headers.count
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 1
}
//Choosing the responsible PrototypCell for the Sections
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
if indexPath.section == 0 {
let cell = tableView.dequeueReusableCell(withIdentifier: "cellBig", for: indexPath) as! HomeVTwoTableViewCell
print("TableViewreloadMain")
cell.collectionView.reloadData()
return cell
}
else if indexPath.section >= 1 {
// getting header Titel for reuse in cell
channelTitle = self.tableView(tableView, titleForHeaderInSection: indexPath.section)!
let cell = tableView.dequeueReusableCell(withIdentifier: "cellSmall", for: indexPath) as! HomeVTwoTableViewCellSmall
// anti Duplicate protection
cell.collectionView.reloadData()
return cell
}
else {
channelTitle = self.tableView(tableView, titleForHeaderInSection: indexPath.section)!
let cell = tableView.dequeueReusableCell(withIdentifier: "cellSmall", for: indexPath) as! HomeVTwoTableViewCellSmall
// anti Duplicate protection
cell.collectionView.reloadData()
return cell
}
}
}
}
My TableViewCell with `CollectionView
import UIKit
import RealmSwift
var communities: Results<Community>?
class HomeVTwoTableViewCellSmall: UITableViewCell{
//serves as a translator from ChannelName to the ChannelId
var channelOverview: [String:String] = ["Channel1": "399", "Channel2": "401", "Channel3": "360", "Channel4": "322", "Channel5": "385", "Channel6": "4"]
//Initiaize the CellChannel Container
var cellChannel: Results<Community>!
//Initialize the translated ChannelId
var channelId: String = ""
#IBOutlet weak var collectionView: UICollectionView!
}
extension HomeVTwoTableViewCellSmall: UICollectionViewDataSource,UICollectionViewDelegate {
//MARK: Datasource Methods
func numberOfSections(in collectionView: UICollectionView) -> Int
{
return 1
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int
{
return (cellChannel.count)
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell
{
guard let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "collectionCellSmall", for: indexPath) as? HomeVTwoCollectionViewCellSmall else
{
fatalError("Cell has wrong type")
}
//removes the old image and Titel
cell.imageView.image = nil
cell.titleLbl.text = nil
//inserting the channel specific data
let url : String = (cellChannel[indexPath.row].pictureId)
let name :String = (cellChannel[indexPath.row].communityName)
cell.titleLbl.text = name
cell.imageView.downloadedFrom(link :"link")
return cell
}
//MARK: Delegate Methods
override func layoutSubviews() {
myGroupCommunity.notify(queue: DispatchQueue.main, execute: {
let realm = try! Realm()
//Getting the ChannelId from Dictionary
self.channelId = self.channelOverview[channelTitle]!
//load data from Realm into variables
self.cellChannel = realm.objects(Community.self).filter("channelId = \(String(describing: self.channelId)) ")
self.collectionView.dataSource = self
self.collectionView.delegate = self
print("collectionView layout Subviews")
self.collectionView.reloadData()
})
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
selectedCommunity = (cellChannel[indexPath.row].communityId)
let home = HomeViewController()
home.showCommunityDetail()
}
}
Thanks in advance.
tl;dr make channelTitle a variable on your cell and not a global variable. Also, clear it, and your other cell variables, on prepareForReuse
I may be mistaken here, but are you setting the channelTitle on the cells once you create them? As I see it, in your viewController you create cells based on your headers, and for each cell you set TableViewController's channelTitle to be the title at the given section.
If this is the case, then the TableViewCell actually isn't receiving any information about what it should be loading before you call reloadData().
In general, I would also recommend implementing prepareForReuse in your HomeVTwoTableViewCellSmall, since it will give you a chance to clean up any stale data. Likely you would want to do something like set cellChannel and channelId to empty strings or nil in that method, so when the cell is reused that old data is sticking around.
ALSO, I just reread the cell code you have, and it looks like you're doing some critical initial cell setup in layoutSubviews. That method is going to be potentially called a lot, but you really only need it to be called once (for the majority of what it does). Try this out:
override the init with reuse identifier on the cell
in that init, add self.collectionView.dataSource = self and self.collectionView.delegate = self
add a didSet on channelTitle
set channelTitle in the viewController
So the code would look like:
var channelTitle: String = "" {
didSet {
self.channelId = self.channelOverview[channelTitle]!
self.cellChannel = realm.objects(Community.self).filter("channelId = \(String(describing: self.channelId)) ")
self.collectionView.reloadData()
}
}
This way you're only reloading your data when the cell is updated with a new channel, rather than every layout of the cell's views.
Sorry... one more addition. I wasn't aware of how your channelTitle was actually being passed. As I see it, you're using channelTitle as a global variable rather than a local one. Don't do that! remove channelTitle from where it is currently before implementing the code above. You'll see some errors, because you're setting it in the ViewController and accessing it in the cell. What you want is to set the channelTitle on the cell from the ViewController (as I outlined above). That also explains why you were seeing the same data across all three cells. Basically you had set only ONE channelTitle and all three cells were looking to that global value to fetch their data.
Hope that helps a little!
(also, you should be able to remove your else if block in the cellForRowAtIndexPath method, since the else block that follows it covers the same code. You can also delete your viewDidLoad, since it isn't doing anything, and you should, as a rule, see if you can get rid of any !'s because they're unsafe. Use ? or guard or if let instead)
I am having a problem at the moment, I have hooked up firebase to my app, created users able to post images to firebase, and to loop through posts to find the following users to create a feed. Only one problem, a tutorial I have been following to make the feed section, includes a void = downloadurl(with: String) and I cannot find this function. I have imported the same modules and app is nearly cloned to his. I am quite confused and was hoping someone could help out. Here is the collectionview cell at the moment:
func collectionView(_ collectionView: UICollectionView,
numberOfItemsInSection section: Int) -> Int {
return posts.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt
indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell",
for: indexPath) as! UserFeedCollectionViewCell
-> cell.myImage. downloadImage(from: String) <- does not exist, or
doesn't show up.
cell.myImage.layer.cornerRadius = 12.0
cell.myImage.clipsToBounds = true
return cell
}
The youtube tutorial is this link: https://youtu.be/fw7ySRFtX_M
and at exactly 35 minutes he shows you how to download the cell image. I have code for creating the feed, but this code is not imortant, and I have firebase and uikit imported.
Please give any tips if you can! Thank You (:
Here's the code for the downloadImage function. It is an extension of UIImageView. The extension should be placed outside of any classes.
class UsersViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
// deleted to save space
}
extension UIImageView {
func downloadImage(from imgURL: String!) {
let url = URLRequest(url: URL(string: imgURL)!)
let task = URLSession.shared.dataTask(with: url) {
(data, response, error) in
if error != nil {
print(error!)
return
}
DispatchQueue.main.async {
self.image = UIImage(data: data!)
}
}
task.resume()
}
}
This is not a built-in function or anything that is innate to Firebase or iOS. In the video, the author mentions that he created this function in his previous video, so you should probably find his previous video and/or download the final project to see what he did.
(There are also lots of great third party library like PINRemoteImage that provide some similar tools for you -- you might want to look at one of them, as well.)
After reading through a bunch of other questions on SO about reloading Firebase observeEventType observers, I am pretty confused. I am adding my observer dictionaries to a variable accessible within the entire controller. I then assign that value to the data source dictionary and it loads all of the previously added children.
However, once I try to add new values from another simulator or manually inputting within the backend, my global dictionary updates with the new value, but my data source variable does not. Once I leave the controller it will eventually update, but it defeats the purpose of using Firebase.
I think an open observer should be in viewWillAppear, but a bunch of sources online seemed to have it in viewDidLoad.
I am using a segmented control to go through each custom class, which may be causing the issue. The setup is one collection view controller whose cells are custom collection views that are cells as well.
override func viewWillAppear(animated: Bool) {
super.viewWillAppear(animated)
self.loadFireData()
}
func loadFireData() {
if let locationId = location.locationId {
let postQuery = ref.child("Posts").child(selectedRegion).child(locationId).queryOrderedByChild("descTime")
postQuery.observeEventType(.ChildAdded, withBlock: { (snap) in
if snap.exists() {
let postQuery = snap.value! as! [String: AnyObject]
let feedPost = FeedModel()
feedPost.value = postQuery["value"] as? String
feedPost.key = postQuery["key"] as? Int
feedPost.balance = postQuery["balance"] as? Double
self.post.append(feedPost)
dispatch_async(dispatch_get_main_queue(), {
self.collectionView!.reloadData()
})
}
}
})
}
}
override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
if indexPath.section == 1 {
let cell = collectionView.dequeueReusableCellWithReuseIdentifier(feedCellId, forIndexPath: indexPath) as! LocationFeedCell
cell.location = location
//this doesn't seem to be updating here
cell.posts = posts
return cell
}
Any help will be greatly appreciated
you are only adding feetpost into post array. So after reload collectionview, you should add newest feetpost in to your custom cell's label according to indexpath.row
if indexPath.section == 1 {
let cell = collectionView.dequeueReusableCellWithReuseIdentifier(feedCellId, forIndexPath: indexPath) as! LocationFeedCell
cell.location = location
//Replace this below line:
cell.posts = post[indexpath.row] as! String
return cell
}
I am using Realm as the alternative for coredata for the first time.
Sadly, I had this bumpy scrolling issue(It is not too bad, but quite obvious) for collectionView when I try Realm out. No data were downloaded blocking the main thread, I use local stored image instead.
Another issue is when I push to another collectionVC, if the current VC will pass data to the other one, the segue is also quite bumpy.
I am guessing it is because of the way I write this children property in the Realm Model. But I do not know what might be the good way to compute this array of array value (merging different types of list into one)
A big thank you in advance!!
Here is the main model I use for the collectionView
class STInstitution: STHierarchy, STContainer {
let boxes = List<STBox>()
let collections = List<STCollection>()
let volumes = List<STVolume>()
override dynamic var _type: ReamlEnum {
return ReamlEnum(value: ["rawValue": STHierarchyType.institution.rawValue])
}
var children: [[AnyObject]] {
var result = [[AnyObject]]()
var tempArr = [AnyObject]()
boxes.forEach{ tempArr.append($0) }
result.append(tempArr)
tempArr.removeAll()
collections.forEach{ tempArr.append($0) }
result.append(tempArr)
tempArr.removeAll()
volumes.forEach{ tempArr.append($0) }
result.append(tempArr)
return result
}
var hierarchyProperties: [String] {
return ["boxes", "collections", "volumes"]
}
}
Here is how I implement the UICollectionViewController:
override func viewDidLoad() {
super.viewDidLoad()
self.collectionView?.alwaysBounceVertical = true
dataSource = STRealmDB.query(fromRealm: realm, ofType: STInstitution.self, query: "ownerId = '\(STUser.currentUserId)'")
}
// MARK: - datasource:
override func numberOfSections(in collectionView: UICollectionView) -> Int {
// #warning Incomplete implementation, return the number of sections
return 1
}
override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
// #warning Incomplete implementation, return the number of items
guard let dataSource = dataSource else { return 0 }
return dataSource.count
}
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: reuseIdentifier, for: indexPath) as! STArchiveCollectionViewCell
guard let dataSource = dataSource,
dataSource.count > indexPath.row else {
return cell
}
let item = dataSource[indexPath.row]
DispatchQueue.main.async {
cell.configureUI(withHierarchy: item)
}
return cell
}
// MARK: - Open Item
func pushToDetailView(dataSource: [[AnyObject]], titles: [String]) {
guard let vc = storyboard?.instantiateViewController(withIdentifier: STStoryboardIds.archiveDetailVC.rawValue) as? STArchiveDetailVC
else { return }
vc.dataSource = dataSource
vc.sectionTitles = titles
self.navigationController?.pushViewController(vc, animated: true)
}
override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
guard let dataSource = self.dataSource,
dataSource.count > indexPath.row else {
return
}
let item = dataSource[indexPath.row]
self.pushToDetailView(dataSource: item.children, titles: item.hierarchyProperties)
}
Modification(more codes on configureUI):
// configureUI
// data.type is an enum type
func configureUI<T: STHierarchy>(withHierarchy data: T) {
print("data", kHierarchyCoverImage + "\(data.type)")
titleLabel.text = data.title
let image = data.type.toUIImage()
self.imageView.image = image
}
// toUIImage of enum data.type
func toUIImage() -> UIImage {
let key = kHierarchyCoverImage + "\(self.rawValue)" as NSString
if let image = STCache.imageCache.object(forKey: key) {
return image
}else{
print("toUIImage")
let defaultImage = UIImage(named: "institution")
let image = UIImage(named: "\(self)") ?? defaultImage!
STCache.imageCache.setObject(image, forKey: key)
return image
}
}
If your UI is bumpy when you're scrolling, it simply means the operations you're performing in collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell are too heavy.
Realm itself is structured in such a way that reading data from objects is very fast, so you shouldn't be seeing substantial dropped frames if all you're doing is populating a cell with values from Realm.
A couple of considerations:
If you're calling item.children inside the cellForItem block method, since you're manually looping through and paging in every Realm object doing that, that will cause frame drops. If you are, it'd be best to either do that ahead of time, or re-desing the logic to only access those arrays when absolutely needed.
You mentioned you're including images. Even if the images are on disk, unless you force image decompression ahead of time, Core Animation will lazily decompress the image at draw time on the main thread which can severely kill scroll performance. See this question for more info.
The cellForItemAt method call should already be on the main thread, so configuring your cell in a DispatchQueue.main.async closure seems un-necessary, and given that it's not synchronous, may be causing additional issues by running out of order.
Collection views are notoriously hard for performance since entire rows of cells used to be created and configured in one run loop iteration. This behavior was changed in iOS 10 to spread cell creation out across multiple run loop iterations. See this WWDC video for tips on optimizing your collection view code to take advantage of this.
If you're still having trouble, please post up more of your sample code; most importantly, the contents of configureUI. Thanks!
Turned out I was focusing on the wrong side. My lack of experience with Realm made me feel that there must be something wrong I did with Realm. However, the true culprit was I forgot to define the path for shadow of my customed cell, which is really expensive to draw repeatedly. I did not find this until I used the time profile to check which methods are taking the most CPU, and I should have done it in the first place.