I thought the same but it is obvious you want to protect your content. I guess one solution would be to make and app that allows downloads within the app. Something like the Netflix app where you can download content but only watch it in it. But then it should probably be a Mac App since most of us watch the videos from our Macs when following the tutorials... Idk just a thought. Easier said done.

Check this out, works fine with me. https://github.com/dzenbot/DZNEmptyDataSet

To do it without any third party, check if the datasnapshot value has no children and render a custom Cell instead.

Thnx

Question is where to do that, in viewDidLoad?

Getting this error also : 'NSInvalidArgumentException', reason: 'UICollectionView must be initialized with a non-nil layout parameter' but is set: func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize { return CGSize(width: view.frame.width, height: 100) }

Now I see that indeed it's working but I had to change the creationDate to a negative value to start sorting properly (newest at the top). But still when I upload a photo and the collectionView updates, the photo appears at the bottom. When I launch the app again, it's at the correct location (first at the top)

OK, I figured it out. I changed posts.append(post) to posts.insert(post, at: 0) in fetchOrderedPosts and everything works perfectly now :)

It's indeed sorted in the right order, but it seems like Firebase only returns the posts in ascending order. You can insert each post to index-0 of your posts array on your end. Like you, I also thought that queryOrdered was supposed to reverse the order with most recent first.

you can change self.posts.append(post) to self.posts.insert(post, at: 0) you will still need to make sure firebase is ordered the query before inserting i think

Hey Brian, I think my app is in a bad state when I fire load images. I apologise for the long reply here. I tried your code and photos still repeated so I went back to break points in fetchUser() and fetchPosts() and discovered errors which I didn't notice earlier. 1) Fire fetchUser() and console shows uid unable to read data i.e. user is nil. which is odd. Error reads: firebaseInstagram[4183:106220] NSURLSession/NSURLConnection HTTP load failed (kCFStreamErrorDomainSSL, -9806) 2) Then I fire fetchPosts() breakpoint at ref.observeSingleEvent(of: .value, with: { (snapshot) in and I get this really long error: firebaseInstagram[4245] <Error> [Firebase/Core][I-NET901017] <Firebase/Network/ERROR> Encounter network error. Code, error: -1200, Error Domain=NSURLErrorDomain Code=-1200 "An SSL error has occurred and a secure connection to the server cannot be made." UserInfo={NSURLErrorFailingURLPeerTrustErrorKey=<SecTrustRef: 0x60800012e1a0>, NSLocalizedRecoverySuggestion=Would you like to connect to the server anyway?, _kCFStreamErrorDomainKey=3, _kCFStreamErrorCodeKey=-9806, NSErrorPeerCertificateChainKey=( "<cert(0x7fa0d4824600) s: *.googleapis.com i: Google Internet Authority G2>", "<cert(0x7fa0d4826000) s: Google Internet Authority G2 i: GeoTrust Global CA>", "<cert(0x7fa0d481ee00) s: GeoTrust Global CA i: Equifax Secure Certificate Authority>" ), NSUnderlyingError=0x60000005f4d0 {Error Domain=kCFErrorDomainCFNetwork Code=-1200 "(null)" UserInfo={_kCFStreamPropertySSLClientCertificateState=0, kCFStreamPropertySSLPeerTrust=<SecTrustRef: 0x60800012e1a0>, _kCFNetworkCFStreamSSLErrorOriginalValue=-9806, _kCFStreamErrorDomainKey=3, _kCFStreamErrorCodeKey=-9806, kCFStreamPropertySSLPeerCertificates=( "<cert(0x7fa0d4824600) s: *.googleapis.com i: Google Internet Authority G2>", "<cert(0x7fa0d4826000) s: Google Internet Authority G2 i: GeoTrust Global CA>", "<cert(0x7fa0d481ee00) s: GeoTrust Global CA i: Equifax Secure Certificate Authority>" )}}, NSLocalizedDescription=An SSL error has occurred and a secure connection to the server cannot be made., NSErrorFailingURLKey=https://play.googleapis.com/log, NSErrorFailingURLStringKey=https://play.googleapis.com/log, NSErrorClientCertificateStateKey=0} 2017-05-26 14:04:39.900 firebaseInstagram[4245] <Error> [Firebase/Core][I-COR000020] Error posting to Clearcut: Error Domain=NSURLErrorDomain Code=-1200 "An SSL error has occurred and a secure connection to the server cannot be made." UserInfo={NSURLErrorFailingURLPeerTrustErrorKey=<SecTrustRef: 0x60800012e1a0>, NSLocalizedRecoverySuggestion=Would you like to connect to the server anyway?, _kCFStreamErrorDomainKey=3, _kCFStreamErrorCodeKey=-9806, NSErrorPeerCertificateChainKey=( "<cert(..) s: *.googleapis.com i: Google Internet Authority G2>", "<cert(..) s: Google Internet Authority G2 i: GeoTrust Global CA>", "<cert(..) s: GeoTrust Global CA i: Equifax Secure Certificate Authority>" ), NSUnderlyingError=0x60000005f4d0 {Error Domain=kCFErrorDomainCFNetwork Code=-1200 "(null)" UserInfo={_kCFStreamPropertySSLClientCertificateState=0, kCFStreamPropertySSLPeerTrust=<SecTrustRef:..>, _kCFNetworkCFStreamSSLErrorOriginalValue=-9806, _kCFStreamErrorDomainKey=3, _kCFStreamErrorCodeKey=-9806, kCFStreamPropertySSLPeerCertificates=( "<cert(..) s: *.googleapis.com i: Google Internet Authority G2>", "<cert(..) s: Google Internet Authority G2 i: GeoTrust Global CA>", "<cert(..) s: GeoTrust Global CA i: Equifax Secure Certificate Authority>" )}}, NSLocalizedDescription=An SSL error has occurred and a secure connection to the server cannot be made., NSErrorFailingURLKey=https://play.googleapis.com/log, NSErrorFailingURLStringKey=https://play.googleapis.com/log, NSErrorClientCertificateStateKey=0}, with Status Code: 0 { 3) Finally when I fire through, all photos load with repeats. So I'm not sure why I'm getting the SSL error?

I guess that setting App Transport Security to allow arbitrary uploads will NOT work in this case...

Hey Brian, My bad. The code checks for similar photo URLs, not similar photos. Of course my posts will repeat photos if I share the same photo again because same photos will have different URLs... haha.

can i check equality of two post's UID instead of image url ? then return/exit it if it is duplicated, thanks

thanks so much for a prompt reply, i watched the links you provided, if i understand correctly, it is about dequed cells loads wrong images, but my app is really loading duplicate cells, text and image is the same, because i add an extra refresh controller letting user refresh the tableview/collectionview. (which i think is kinda popular exist in most social app: facebook , wechat etc.) everytime after i refreshed the tableview/collectionview, add a post, in the main timeline duplicate posts appear right away, no need to scroll at all. i do set post = [ ] back to empty. is there anyway i can use if-else condition to check that if there is duplicate Post cell uids, if there is duplicate ones ,don't let post cell add or remove it. if anyone here has ever encountered the same problem please please let me know. it is my first ever app, i try to release on app store after so long self-study, : ) , thanks

Of course. Sorry about that. I hate simple mistakes like that. This course is awesome btw!

Thank you for your quick response!

what you can do, is an MD5 Check of the source image and send user a warning, that the same image already posted. You have to do this how brian said, before upload/sharing it. But if the user modfining the source with any photo app, than the md5 sum changes. Or if user convert source to other size... this checks only prevent to upload "same file" not maybe same "picture" if you understand what i mean.

Oops.. note that "pathArray.append(path)" should be "paths.append(path)" as I had renamed that.

I should note that there is almost certainly a better way to do the initial loading of reversed posts. This approach seems to be more geared towards pagination (without reloading ALL data each time). As it stands, it has an awkward load animation for the initial set of posts.

I wrote something like this https://pastebin.com/NBsPJCQ8

Ok, thanks Brian.

But when I use observe.value, the order of post is incorrect :(

I know that when I add a new post, my current code just adds to the Post(dictionary), thereby creating multiple copies of the posts. I'm just missing something simple, just need to append to Post(dictionary).

Absolutely! Not many online tutorials like yours out there, especially ones that uses Firestore. Thank you! Any temporary suggestions for my original post?

I figured as much, I'm just having a hard time "massaging" the snapshot to return a dictionary. New to Firestore, so i'm a little lost.

Found a solution, in case anyone else came up with the same problem: fileprivate func fetchOrderedPosts() { guard let uid = Auth.auth().currentUser?.uid else { return } Firestore.firestore() .collection("users") .document(uid) .collection("posts") .order(by: "creationDate", descending: true) .addSnapshotListener { (snapshot, err) in if let err = err { print("Failed to get posts from user:", err) return } self.posts.removeAll() //*** HERE'S MY FIX *** guard let snapshot = snapshot else { return } snapshot.documents.forEach({ (data) in let dictionary = data.data() as [String : Any] let post = Post(dictionary: dictionary) self.posts.append(post) }) self.collectionView.reloadData() } } If anyone else comes up with a more efficient solution, please let me know. I have no idea if this a good fix, but it works.

Thanks for this