Problem:

On iOS 10 and lower, when adding a trailing SwipeAction to a Row, this action is cast to a UITableViewRowAction and returned from tableView(_:editActionsForRowAt:) in FormViewController. Unfortunately the same does not happen on iOS 11, since there a SwipeAction is cast to UIContextualAction instead of UITableViewRowAction, leaving tableView(_:editActionsForRowAt:) to return nothing and making UIKit fall back to default behavior.

This leads to inconsistent behavior between iOS versions, which is, of course, unfavorable.

Solution:

I propose the introduction of tableViewRowAction(forRow:) alongside the already existing func contextualAction(forRow:). This way, in tableView(_:editActionsForRowAt:), we can explicitly request UITableViewRowActions and establish consistent behavior across iOS versions.

Demo:

Given the following form setup…

form     Section("Rows")
	<<< LabelRow {
		$0.title = "← Delete me!"
		
		let action = SwipeAction(style: .destructive, title: " Bam! 💥", handler: { (action, row, completionBlock) in
			completionBlock?(true)
		})
		
		action.backgroundColor = UIColor.darkGray
		
		$0.trailingSwipe.actions = [action]
	}

tableView.setEditing(true, animated: false)

… the current behavior when tapping the delete icon on iOS 11 is as follows:

The expected behavior, however, is the same as it already is on iOS 10 and lower: