Converting iOS9 coalesced touches drawing code for iOS8 and iOS7 compatibility - ios

Question

I have the below code from a project available at: https://github.com/FlexMonkey/SmoothScribble/tree/master/SmoothScribble
Currently this project only runs on iOS9 as the project uses UIStackView and coalescedTouchesForTouch which are only available for iOS9. However I wish to convert the project to make it available for iOS7 and iOS8 as well. How do I go about doing that?
I think I might have a handle on how I might go about replacing UIStackView with a UIView. However, how do I handle sections that refer to coalescedTouches?
For instance, how do I convert the below code snippet so that it conforms to a traditional touchesMoved that works on iOS8 and iOS9?
override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent?)
{
guard let
touch = touches.first,
coalescedTouches = event?.coalescedTouchesForTouch(touch),
touchOrigin = touchOrigin
else
{
return
}
coalescedTouches.forEach
{
hermiteScribbleView.appendScribble($0.locationInView(touchOrigin))
simpleScribbleView.appendScribble($0.locationInView(touchOrigin))
}
}
import UIKit
class ViewController: UIViewController
{
let stackView = UIStackView()
let hermiteScribbleView = HermiteScribbleView(title: "Hermite")
let simpleScribbleView = SimpleScribbleView(title: "Simple")
var touchOrigin: ScribbleView?
override func viewDidLoad()
{
super.viewDidLoad()
view.addSubview(stackView)
stackView.addArrangedSubview(hermiteScribbleView)
stackView.addArrangedSubview(simpleScribbleView)
}
override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?)
{
guard let
location = touches.first?.locationInView(self.view) else
{
return
}
if(hermiteScribbleView.frame.contains(location))
{
touchOrigin = hermiteScribbleView
}
else if (simpleScribbleView.frame.contains(location))
{
touchOrigin = simpleScribbleView
}
else
{
touchOrigin = nil
return
}
if let adjustedLocationInView = touches.first?.locationInView(touchOrigin)
{
hermiteScribbleView.beginScribble(adjustedLocationInView)
simpleScribbleView.beginScribble(adjustedLocationInView)
}
}
override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent?)
{
guard let
touch = touches.first,
coalescedTouches = event?.coalescedTouchesForTouch(touch),
touchOrigin = touchOrigin
else
{
return
}
coalescedTouches.forEach
{
hermiteScribbleView.appendScribble($0.locationInView(touchOrigin))
simpleScribbleView.appendScribble($0.locationInView(touchOrigin))
}
}
override func touchesEnded(touches: Set<UITouch>, withEvent event: UIEvent?)
{
hermiteScribbleView.endScribble()
simpleScribbleView.endScribble()
}
override func motionBegan(motion: UIEventSubtype, withEvent event: UIEvent?)
{
if motion == UIEventSubtype.MotionShake
{
hermiteScribbleView.clearScribble()
simpleScribbleView.clearScribble()
}
}
override func viewDidLayoutSubviews()
{
stackView.frame = CGRect(x: 0,
y: topLayoutGuide.length,
width: view.frame.width,
height: view.frame.height - topLayoutGuide.length).insetBy(dx: 10, dy: 10)
stackView.axis = view.frame.width > view.frame.height
? UILayoutConstraintAxis.Horizontal
: UILayoutConstraintAxis.Vertical
stackView.spacing = 10
stackView.distribution = UIStackViewDistribution.FillEqually
}
}
Full project code available at: project available at: https://github.com/FlexMonkey/SmoothScribble/tree/master/SmoothScribble

Answer 1

Yesterday I also had a question on compatibility and it turned out that it could be solved easily by Availability Condition, like this:
if #available(iOS 9.0, *) {
let store = CNContactStore()
} else {
// Fallback on earlier versions
}
You can read this article to know more about it.
http://useyourloaf.com/blog/checking-api-availability-with-swift.html
I do not know if we have the same problem. But, in my view, I could have two snippets of code comforming to iOS 9 and iOS 8 respectively, and use Availability Condition or #available Attribute to resolve compatibility problem.