MSPeekCollectionViewDelegateImplementation

Version 3.0.0 is here! 🎉

The peeking logic is now done using a custom UICollectionViewLayout which makes it easier to integrate and will introduce less bugs! (And hopefully it will solve all the issues you were facing)

Migrating from 2.0.0 to 3.0.0

I've tried to keep minimal effort to migrate from v2 to v3. Here are the steps:

1- Replace MSPeekCollectionViewDelegateImplementation initialization with MSCollectionViewPeekingBehavior

2- On your collectionView, call configureForPeekingBehavior like this:

collectionView.configureForPeekingBehavior(behavior: behavior)

3- Set the collection view's delegate as the view controller (Or any other class you want)

4- In the collection view delegate function scrollViewWillEndDragging, call the behavior's scrollViewWillEndDragging like this:

func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
        behavior.scrollViewWillEndDragging(scrollView, withVelocity: velocity, targetContentOffset: targetContentOffset)
}

5- ???

6- Profit 💰

You can check out the example for a detailed use

Introduction

Current design trends require complex designs which allow horizontal scrolling inside vertical scrolling. So to show the users that they can scroll vertically, a peeking item should be shown on the side. This library does exactly that. I wrote this library because there's no pod that does this simple feature. Also, other libraries require me to inherit from a UICollectionViewController, which doesn't give alot of freedom if I'm inheriting from other View Controllers.

Example

To run the example project, clone the repo, and run pod install from the Example directory first.

Requirements

• XCode 11.2.1
• Swift 5

This pod will probably work on older versions of XCode but I haven't tested it.

Installation

MSPeekCollectionViewDelegateImplementation is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod 'MSPeekCollectionViewDelegateImplementation'

Usage

Storyboard

1. Drag-Drop a UICollectionView

2. Set the reuse identifier for the collection view's cell to Cell

3. Create a reference for the collection view

@IBOutlet weak var collectionView: UICollectionView!

4. Bind collection view to outlet

5. Import library

import MSPeekCollectionViewDelegateImplementation

6. Create a variable of type MSCollectionViewPeekingBehavior

var behavior: MSCollectionViewPeekingBehavior!

7. In viewDidLoad(), , initialize the behavior and configure the collectionView for peek behavior:

behavior = MSCollectionViewPeekingBehavior()
collectionView.configureForPeekingBehavior(behavior: behavior)

Or you can use whatever arguments from the ones below (Can be combined together as needed):

behavior = MSCollectionViewPeekingBehavior(cellSpacing: 10)

behavior = MSCollectionViewPeekingBehavior(cellPeekWidth: 20)

//minimumItemsToScroll is the minimum number of items that can be scrolled
behavior = MSCollectionViewPeekingBehavior(minimumItemsToScroll: 1)

//maximumItemsToScroll is the maximum number of items that can be scrolled if the scroll distance is large
behavior = MSCollectionViewPeekingBehavior(maximumItemsToScroll: 3)

//numberOfItemsToShow is the number of items that will be shown at the same time.
behavior = MSCollectionViewPeekingBehavior(numberOfItemsToShow: 3)

8. In viewDidLoad(), set the collection view's delegate to self:

collectionView.delegate = self

9. In the collection view delegate function scrollViewWillEndDragging, call the behavior's scrollViewWillEndDragging like this:

func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
        behavior.scrollViewWillEndDragging(scrollView, withVelocity: velocity, targetContentOffset: targetContentOffset)
}

10. Create the data source implementation as an extension for the ViewController

extension ViewController: UICollectionViewDataSource {
    func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 1
    }
    
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 4
    }
    
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath)
        //TODO: Configure cell
        return cell
    }
}

11. In viewDidLoad(), Set the collection view's data source to self

collectionView.dataSource = self

Working Example

import UIKit
import MSPeekCollectionViewDelegateImplementation

class ViewController: UIViewController {
    
    @IBOutlet weak var collectionView: UICollectionView!
    var behavior = MSCollectionViewPeekingBehavior()

    override func viewDidLoad() {
        super.viewDidLoad()
        collectionView.configureForPeekingBehavior(behavior: behavior)
        collectionView.delegate = self
        collectionView.dataSource = self
    }
}

extension ViewController: UICollectionViewDataSource {
    func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 1
    }
    
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 4
    }
    
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath)
        cell.contentView.backgroundColor = UIColor.red
        return cell
    }
}

extension ViewController: UICollectionViewDelegate {
    func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
        behavior.scrollViewWillEndDragging(scrollView, withVelocity: velocity, targetContentOffset: targetContentOffset)
    }
    
    func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
        print(behavior.currentIndex)
    }
}

Features

Scrolling to a specific item

The MSCollectionViewPeekingBehavior now has a function to scroll to a specific index

public func scrollToItem(at index: Int, animated: Bool)

You can do something like:

behavior.scrollToItem(at: 1, animated: true)

Listen to index changes

You can use the scroll view's delegate function to do that (Make sure you conform to UICollectionViewDelegate):

func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
    print(behavior.currentIndex)
}

Customization

Vertical Scroll Direction

The implementation supports collection views with vertical directions and will automatically position cells correctly, you can set the scrolling and peeking to be vertical using:

delegate = MSCollectionViewPeekingBehavior(scrollDirection: .vertical)
collectionView.configureForPeekingBehavior(behavior: behavior)

Author

Maher Santina, [email protected]

Sponsor

If you're liking this repo I'd really appreciate it if you sponsor me (Orange Juice) so that I can continue supporting this project. I'm also working on adding more reusable UI elements similar to this one to make developer's lives easier. Please see my sponsor page for more details

Contributing

Any contribution is highly appreciated, please see CONTRIBUTING.md for more info.

License

MSPeekCollectionViewDelegateImplementation is available under the MIT license. See the LICENSE file for more info.