Unfortunately Apple doesn't provide an accessory type property for UICollectionViewCell, such as for UITableViewCell, so I provide a custom way to create a checkmark. A just a simple view which draws programmatically a checkmark with some styles.
CocoaPods:
pod 'CheckMarkView'
Manual:
Copy CheckMarkView.swift to your project.
You can create from the code or set up a view in the Storyboard, XIB.
let checkMarkView = CheckMarkView()
For controlling you have checked property. And style property for the unchecked view. There are some styles:
enum CheckMarkStyle: Int { case nothing case openCircle case grayedOut }
CheckMarkView is available under the MIT license. See the LICENSE file for more info.