Active cell support

[HristiyanZahariev]

I want to congratulate you for this lib, it's very cool. However, I think one key feature is missing and it is an active cell support. Is there a way to easily understand (from the controller) which cell is active?

[MaherKSantina]

Thank you Hristiyan for raising this issue. I think this is a common case scenario that other developers might experience. So I'm going to do an update to add this functionality to the repository. However, there's a solution you can use for the time being before I update the pod:

1- You need to subclass the MSPeekCollectionViewDelegateImplementation to monitor when the user scrolls to a new cell (I assume you need to update the index in the controller every time the user scrolls a cell). You can do that as follows:

class CustomDelegateImplementation: MSPeekCollectionViewDelegateImplementation {
    
    override func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
        //Call the super function to handle the peeking behavior on scroll
        super.scrollViewWillEndDragging(scrollView, withVelocity: velocity, targetContentOffset: targetContentOffset)
        //Get the new active index
        let activeIndex = self.scrollView(scrollView, indexForItemAtContentOffset: targetContentOffset.pointee)
        // TODO: Return activeIndex to the view controller
    }
}

2- To return the active index to the view controller, we can create a delegate protocol for that and let the view controller conform to this protocol:

protocol PeekImplementationActiveDelegate: AnyObject {
    func peekImplementation(_ peekImplementation: CustomDelegateImplementation, didChangeActiveIndexTo activeIndex: Int)
}

3- Now, we create a delegate variable in the CustomDelegateImplementation:

weak var delegate: PeekImplementationActiveDelegate?

4- Call the delegate function in the function we overriden in step 1:

override func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
    //Call the super function to handle the peeking behavior on scroll
    super.scrollViewWillEndDragging(scrollView, withVelocity: velocity, targetContentOffset: targetContentOffset)
    //Get the new active index
    let activeIndex = self.scrollView(scrollView, indexForItemAtContentOffset: targetContentOffset.pointee)
    //Pass the active index to the delegate
    delegate?.peekImplementation(self, didChangeActiveIndexTo: activeIndex)
}

5- Add an extension for your view controller which conforms to PeekImplementationActiveDelegate:

extension ViewController: PeekImplementationActiveDelegate {
    func peekImplementation(_ peekImplementation: CustomDelegateImplementation, didChangeActiveIndexTo activeIndex: Int) {
        // TODO: Save active index in view controller
        print(activeIndex)
    }
}

6- Create a variable for the implementation in the view controller:

var implementation: CustomDelegateImplementation!

7- In your viewDidLoad function, create a new instance for the implementation and set the delegate to self

override func viewDidLoad() {
    super.viewDidLoad()
    implementation = CustomDelegateImplementation()
    implementation.delegate = self
}

Final Implementation:

import UIKit
import MSPeekCollectionViewDelegateImplementation

class ViewController: UIViewController {
    
    var implementation: CustomDelegateImplementation!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        implementation = CustomDelegateImplementation()
        implementation.delegate = self
    }

}

extension ViewController: PeekImplementationActiveDelegate {
    func peekImplementation(_ peekImplementation: CustomDelegateImplementation, didChangeActiveIndexTo activeIndex: Int) {
        // TODO: Save active index in view controller
        print(activeIndex)
    }
}

protocol PeekImplementationActiveDelegate: AnyObject {
    func peekImplementation(_ peekImplementation: CustomDelegateImplementation, didChangeActiveIndexTo activeIndex: Int)
}

class CustomDelegateImplementation: MSPeekCollectionViewDelegateImplementation {
    
    weak var delegate: PeekImplementationActiveDelegate?
    
    override func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
        //Call the super function to handle the peeking behavior on scroll
        super.scrollViewWillEndDragging(scrollView, withVelocity: velocity, targetContentOffset: targetContentOffset)
        //Get the new active index
        let activeIndex = self.scrollView(scrollView, indexForItemAtContentOffset: targetContentOffset.pointee)
        //Pass the active index to the delegate
        delegate?.peekImplementation(self, didChangeActiveIndexTo: activeIndex)
    }
}

[HristiyanZahariev]

Thank you very much 💯

[MaherKSantina]

@HristiyanZahariev you're welcome! Please close this issue if it fixes your problem. Do you think you can create a pull request to add this functionality to the main class?

[HristiyanZahariev]

I think I can do it on the weekend. If it's not too late I will create a pull request

[MaherKSantina]

@HristiyanZahariev sorry for the late reply. I have updated the pod to include active cell support. You can check more information in the merged PR here. Please let me know if you have any more issues