Objective C support

[benemdon]

Objective C support

[BenEmdon]

Instead of modifying the swift implementation of currentCenteredPage, you could write a new calculated variable and implement it exactly like so #38 (comment).

Deciding the name of such a variable is the hard part 😅 Here are some name ideas:

• currentCenteredPageOBJC
• currentCenteredIndex

[BenEmdon]

@duraki Take care of yourself 💖I totally feel you and I have also had less bandwidth during this time.

I'll add the help wanted label in case anyone else wants to pick this up 👋

[BenEmdon]

@farazhaider88 I think the best place to get an answer to this question is to look at Apple's documentation. https://developer.apple.com/documentation/swift/imported_c_and_objective-c_apis/importing_swift_into_objective-c

I am not sure this package will work out of the box with Objective-C (as I have not tried). If you find a way to make this work please report/contribute back!

[duraki]

I don't want to open new issue but I've tried this extension with Objective-C and it works very well. The only problem is we can't observe the currentCenteredPage.

NSInteger *currentIndex = self.centeredCollectionViewFlowLayout.currentCenteredPage;

Throws error Property 'currentCenteredPage' not found on object of type 'CenteredCollectionViewFlowLayout *'. I'm guessing it's because of Int? but I'm not proficient with Swift enough. Any input is highly appreciated.

Thanks!

[duraki]

Taken from Apple documentation:

Optional values of non-Objective-C types aren't bridged into Objective-C.

@BenEmdon

[duraki]

This is how I did it (hotfix, not sure how smart it is):

    /// Calculates the current centered page.
    @objc public var currentCenteredPage: Int {
        guard let collectionView = collectionView else { return -1 }
        let currentCenteredPoint = CGPoint(x: collectionView.contentOffset.x + collectionView.bounds.width/2, y: collectionView.contentOffset.y + collectionView.bounds.height/2)
        
        return collectionView.indexPathForItem(at: currentCenteredPoint)?.row ?? -1
    }

Returns -1 if no cell is at centered point.

[BenEmdon]

@duraki this seems like a reasonable change, but it would break the API. If you would like an API to observe currentCenteredPage we could instead create a new API. If you submit a PR, I will definitely review it 😉

[duraki]

Well, I can try. What do you suggest as a starting point regarding the Swifts version of currentCenteredPage?

[BenEmdon]

@duraki still interested in doing this?

[duraki]

Sure, although a bit busy right now with the case of pandemic. If anyone is able to tackle it down I'm more then available to help.

[wassup-]

To access the current centered page from ObjC, this is probably all you need:

@objc var currentCenteredPageNumber: NSNumber? {
    currentCenteredPage as NSNumber?
}

[github-actions]

This issue has gone a long time without activity, so I will mark it as stale!