The official solution since iOS11 is overriding preferredScreenEdgesDeferringSystemGestures of your UIInputViewController.
https://developer.apple.com/documentation/uikit/uiviewcontroller/2887512-preferredscreenedgesdeferringsys
However, it doesn't seem to work on iOS 13 at least. As far as I understand, that happens due to preferredScreenEdgesDeferringSystemGestures not working properly when overridden inside UIInputViewController, at least on iOS 13.
When you override this property in a regular view controller, it works as expected:
override var preferredScreenEdgesDeferringSystemGestures: UIRectEdge {
return [.left, .bottom, .right]
}
That' not the case for UIInputViewController, though.
UPD: It appears, gesture recognizers will still get .began state update, without the delay. So, instead of following the rather messy solution below, you can add a custom gesture recognizer to handle touch events.
You can quickly test this adding UILongPressGestureRecognizer with minimumPressDuration = 0 to your control view.
Another solution:
My original workaround was calling touch down effects inside hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView?, which is called even when the touches are delayed for the view.
You have to ignore the "real" touch down event, when it fires about 0.4s later or simultaneously with touch up inside event. Also, it's probably better to apply this hack only in case the tested point is inside ~20pt lateral margins.
So for example, for a view with equal to screen width, the implementation may look like:
let edgeProtectedZoneWidth: CGFloat = 20
override func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {
let result = super.hitTest(point, with: event)
guard result == self else {
return result
}
if point.x < edgeProtectedZoneWidth || point.x > bounds.width-edgeProtectedZoneWidth
{
if !alreadyTriggeredFocus {
isHighlighted = true
}
triggerFocus()
}
return result
}
private var alreadyTriggeredFocus: Bool = false
@objc override func triggerFocus() {
guard !alreadyTriggeredFocus else { return }
super.triggerFocus()
alreadyTriggeredFocus = true
}
override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent?) {
super.touchesCancelled(touches, with: event)
alreadyTriggeredFocus = false
}
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
super.touchesEnded(touches, with: event)
alreadyTriggeredFocus = false
}
...where triggerFocus() is the method you call on touch down event. Alternatively, you may override touchesBegan(_:with:).
