Is there a better way to do this scrolling animation in Swift? - ios

Question

I'm trying to add a behavior to part of my app's UI whereby the user can swipe left and this will result in a set of UILabels scrolling in sync together off-screen to the left, but then immediately scrolling back in again but from the right, but with new information contained in them.
The effect is meant to give the impression that you're moving from one "set" of info to the next... like, say, choosing a car before starting a race game... but in reality it is the same views being re-used... scrolling offscreen to have their label.text info updated... then scrolling back in again.
I have the swiping all taken care of. The issue I'm having is that my (working) solution:
UIView.animate(withDuration: 0.2, animations: {
// move label off to the left
self.titleLabel.center.x -= self.view.bounds.width
}, completion: {
$0 ; print("I'm halfway done!")
// teleport view to a location off to the right
self.titleLabel.center.x += 2*(self.view.bounds.width)
// reset label's data
self.titleLabel.text = NEW_INFO
// slide label back on screen from the right
UIView.animate(withDuration: 0.2, animations: {
self.titleLabel.center.x -= self.view.bounds.width
}, completion: nil)
})
Feels trashy like wearing someone else's underwear.
The only reason that $0 is there is to make XCode stop saying:
"Cannot convert value of type '() -> ()' to expected argument type '((Bool) -> Void)?'"
And I'm sure the fact that I'm doing the second part of the animation in a completion block will cause headaches down the road.
Is there a smarter way?
PS - I would prefer not to use any pre-made classes like "ScrollView" or anything like that... these views are all individually interactive and respond to other callbacks etc.
Thanks!

Answer 1

A better approach to something like this would be to use a UIPageViewController.
It will take a bit of learning and set up but is much easier than trying to roll it yourself.
The approach to take with a UIPageViewController is something like this...
Create a data model... to use your analogy...
struct Car {
let image: UIImage
let name: String
}
Then create a UIViewController subclass that will display it.
class CarViewController: UIViewController {
var car: Car? {
didSet {
displayCar()
}
}
func displayCar() {
label.text = car?.name
imageView.image = car?.image
}
}
Then you create a UIPageViewController. Inside this you have an array of cars. And in the function func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? you can then create your CarViewController and pass in the correct Car from the array.
This will then do all your scrolling and displaying and everything is still interactive.
For more information about how this works you can look at tutorials like this one from Ray Wenderlich.
You can also use this to display a part of a page (rather than scrolling the entire screen.