Can't register custom class cell

[firebase]

Can't register custom class cell

[kermankohli]

@pmodernme Have you been able to use custom cells with your section implementation?

[asciimike]

So I think this is actually a bug in Swift and the __kindof(Class) implementation. I can't seem to ever use the appropriate subclass in Swift, even though it works in Obj-C. I just recommend forcing the cast to make this work:

self.dataSource.populateCellWithBlock { (cell: UITableViewCell, obj: NSObject) -> Void in
  // Populate cell as you see fit, like as below
  var customCell = cell as! CustomTableViewCell;
  let snapshot = obj as! FDataSnapshot; // danger this can be null on deletion!
}

Looks like I might have to update the docs as well as bother Apple about why this behavior fails.

[pmodernme]

Yes, using the prototype cell data source construction method.

On Wednesday, November 11, 2015, Kerman [email protected] wrote:

@pmodernme https://github.com/pmodernme Have you been able to use
custom cells with your section implementation?

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#16 (comment)
.

[kermankohli]

@pmodernme @mcdonamp I had tried it before but my custom cell implementation was messed up so it ended up failing - it's all good now though :)

Also quick question, is it possible to execute a certain function to determine the title of that section? An important use case for this would be if you had a boolean, date or number and you don't want the titles to just be raw values which don't make sense (updated_at = 1447059191006). Maybe a method for self.sectionKeyPath with the snapshot being passed and a string to be returned?

[kermankohli]

When multiple objects are edited, I get this error:

*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Invalid update: invalid number of sections. The number of sections contained in the table view after the update (3) must be equal to the number of sections contained in the table view before the update (3), plus or minus the number of sections inserted or deleted (1 inserted, 0 deleted).'

Presumably the data source is getting changed in multiple places without proper handling.

@mcdonamp Will @pmodernme's branch be merged into the actual FirebaseUI or will it remain as is?

[asciimike]

@kermankohli can you please post some code that's causing this so we can repro? We should never have gotten multiple objects at once to update multiple rows, so maybe something isn't being added/removed properly?

We're working on getting 0.3 out (see demm-auth for the latest) by next week, so we'll switch to getting #12 and #13 in after that.

[kermankohli]

Don't think code will be useful here, basically on a presented modal view controller I'm using multi-path writes to update a few objects in my tableview where the sections are based on the "updated_at" child value (which is being written to all the objects).

Also instead of dataSource.array.sectionKeyPath being a string, can it be changed to be a method like:

func returnSectionKeyPath(keypath: String, forSnapshot: FDataSnaphot) -> String {
// code to determine name of section
return nameOfSection
}

Since usually sections can't be read straight from their values (eg bools, dates - stored as epoch, or ids).

[asciimike]

@kermankohli is this bug happening in the sectioning code or in the current 0.2 version?

[kermankohli]

The code from pull request #13, and on

• (void)sectionAddedAtSectionIndex:(NSUInteger)section {
  [self.tableView insertSections:[NSIndexSet indexSetWithIndex:section]
  withRowAnimation:UITableViewRowAnimationAutomatic];
  }

more specifically

[asciimike]

@kermankohli Can you please file as an issue referencing #13 so it can be triaged and tracked appropriately?

[gulci]

Sorry to revive this, but I'm having the same issue and the docs don't really mention this as an issue. I've tried forcing the cast to make it work, but I'm running into the same wall as this person.

I'm still trying to resolve this, but could this... Swift bug? be mentioned in the docs?

[pmodernme]

Many of the bugs in the sectioning pull request are resolved in the
FirebaseSet pull request.

On Friday, February 5, 2016, Mario Muñiz [email protected] wrote:

Sorry to revive this, but I'm having the same issue and the docs don't
really mention this as an issue. I've tried forcing the cast to make it
work, but I'm running into the same wall as this person.
http://stackoverflow.com/questions/33731631/firebaseui-swift-cast-value-of-uitableviewcell-to-custom-class#

I'm still trying to resolve this, but could this... Swift bug? be
mentioned in the docs?

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#16 (comment)
.

[kemalony]

it would be helpfull to share my simple not working code

as document said at http://cocoadocs.org/docsets/FirebaseUI/0.2.5/

i wrote

self.dataSource.populateCellWithBlock { (cell: KoMsgTableViewCell, obj: NSObject) -> Void in
like
self.dataSource.populateCellWithBlock { (cell: YourCustomClass, obj: NSObject)
but not worked it says
expected type is cell:uitableviewcell

then tried that

self.dataSource.populateCellWithBlock { (cell: UITableViewCell, obj: NSObject) -> Void in
    let snap = obj as! FDataSnapshot
    let MyCell = cell as! KoMsgTableViewCell
    MyCell.LblSender.text = snap.childSnapshotForPath("body").value  as! String
}

but it give out fatal error at runtime

fatal error: unexpectedly found nil while unwrapping an Optional value

though I inited by class by

class KoMsgTableViewCell: UITableViewCell {
override init (style: UITableViewCellStyle, reuseIdentifier: String?) {
super.init(style: style, reuseIdentifier: reuseIdentifier)
}

[gulci]

Yes. That's exactly the same problem I ran into. Essentially the same code.

[asciimike]

@kemalony @gulci The unexpectedly found nil likely comes from snap.childSnapshotForPath("body").value as! String since what you should be using is snap.value["body"] as! String. The childSnapshotForPath returns a snapshot (of type FDataSnapshot? in this case, it's nil), not the value of the object (which you assume would be a String), which is why the call is failing: you're saying "trust me it'll be a String" but getting an FDataSnapshot. Check out our docs for more info.

On the other issue of the cell casting not working--again, it's XCode, Swift, and __kindof() not being supported, there's not much we can do other than change the docs ;)

For future reference, the cell and object are both marked as non null (see https://github.com/firebase/FirebaseUI-iOS/blob/master/FirebaseUI/Core/API/FirebaseTableViewDataSource.h#L403), so those are pretty much guaranteed not to fail the casts.

[muratyasarr]

The documentation says we need to use the constructor with "prototypeReuseIdentifier" instead of "cellReuseIdentifier" but I can't see the exact same constructor with the "prototypeReuseIdentifier". The constructors that have "prototypeReuseIdentifier" as parameter do not have "cellClass" parameter that I used with "cellReuseIdentifier". Can you please explain how to use the constructor with the parameter prototypeReuseIdentifier to populate a custom table view cell? If possible, direct me to some tutorial or example code please. Thanks.

Currently the screenshot of my error is:

[asciimike]

@muratyasarr In general, if you're using a storyboard, you put the custom class in the storyboard (specifically, in the prototype cell) rather than register it on the class--the double registration causes a bunch of sticky issues. If you're using Obj-C, you can easily cast in the block to a UITableViewCell or UICollectionViewCell subclass of your choice, as so:

self.dataSource = [[FirebaseTableViewDataSource alloc] initWithRef:firebaseRef prototypeReuseIdentifier:@"<YOUR-REUSE-IDENTIFIER>" view:self.tableView];

[self.dataSource populateCellWithBlock:^(MyCustomCell *cell, FDataSnapshot *snap) {
  // Populate cell as you see fit, like as below
}];
...

If you're using Swift, for the reasons discussed above, __kindof() doesn't seem to work so you're stuck casting in the cell:

self.dataSource = FirebaseTableViewDataSource(ref: firebaseRef prototypeReuseIdentifier: @"<YOUR-REUSE-IDENTIFIER>" view: self.tableView)

self.dataSource.populateCellWithBlock { (cell: UITableViewCell, obj: NSObject) -> Void in
  let newCell = cell as! MyCustomCell
  // Populate cell as you see fit
}
...

When in doubt, the code explains this best: https://github.com/firebase/FirebaseUI-iOS/blob/master/FirebaseUI/Core/Implementation/FirebaseTableViewDataSource.m#L286

We will always return an appropriate cell using dequeueReusableCellWithIdentifier: forIndexPath:indexPath which according to Apple's docs "A __kindofUITableViewCell object with the associated reuse identifier. This method always returns a valid cell."

[asciimike]

Also, this thread has drifted quite a bit, so I'll be locking it. If there's a new, different issue, please file a new issue.