I have an app like a reader. When I touch the right edge of the screen, I go to the next page. When I touch the left edge of the screen, I go to the previous page. My pages contain images. The image is full screen size and 20pt more from one of the edges of the screen. And when I show the page, I want the image move to the right from 0pt to 20pt or left from 0pt to -20pt depending on imageDirection property from json file. I use this code to do this:
reader container:
class ReaderController: UIViewController {
var pagesData = [PageData]()
var imageArray: [UIImage] = []
var index = Int()
var pageIndex: Int = -1
let pageContainer: UIView = {
let view = UIView()
view.translatesAutoresizingMaskIntoConstraints = false
return view
}()
let pageViews: [PageLayout] = {
let view = [PageLayout(), PageLayout()]
view[0].translatesAutoresizingMaskIntoConstraints = false
view[1].translatesAutoresizingMaskIntoConstraints = false
return view
}()
override func viewDidLoad() {
super.viewDidLoad()
loadImages()
setupViews()
setupConstraints()
pageViews[0].index = index
pageViews[0].imageArray = imageArray
pageViews[1].index = index
pageViews[1].imageArray = imageArray
pageViews[0].pageIndex = pageIndex
pageViews[1].pageIndex = pageIndex
pageTransition(animated: false, direction: "fromRight")
}
func setupViews() {
pageContainer.addSubview(pageViews[0])
pageContainer.addSubview(pageViews[1])
view.addSubview(pageContainer)
}
func setupConstraints() {
pageContainer.topAnchor.constraint(equalTo: view.topAnchor, constant: 0.0).isActive = true
pageContainer.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: 0.0).isActive = true
pageContainer.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 0.0).isActive = true
pageContainer.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: 0.0).isActive = true
pageViews[0].topAnchor.constraint(equalTo: pageContainer.topAnchor).isActive = true
pageViews[0].bottomAnchor.constraint(equalTo: pageContainer.bottomAnchor).isActive = true
pageViews[0].leadingAnchor.constraint(equalTo: pageContainer.leadingAnchor).isActive = true
pageViews[0].trailingAnchor.constraint(equalTo: pageContainer.trailingAnchor).isActive = true
pageViews[1].topAnchor.constraint(equalTo: pageContainer.topAnchor).isActive = true
pageViews[1].bottomAnchor.constraint(equalTo: pageContainer.bottomAnchor).isActive = true
pageViews[1].leadingAnchor.constraint(equalTo: pageContainer.leadingAnchor).isActive = true
pageViews[1].trailingAnchor.constraint(equalTo: pageContainer.trailingAnchor).isActive = true
}
func loadData(fileName: Any) -> PagesData {
var url = NSURL()
url = Bundle.main.url(forResource: "text", withExtension: "json")! as NSURL
let data = try! Data(contentsOf: url as URL)
let person = try! JSONDecoder().decode(PagesData.self, from: data)
return person
}
func loadImages() {
for imageIndex in 1...18 { imageArray.append(UIImage(named: "page\(imageIndex)")!) }
}
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
for touch in touches {
if(touch.view == pageViews[0] || touch.view == pageViews[1]) {
let location = touch.location(in: view.self)
if view.safeAreaInsets.left > 30 {
if (location.x > self.view.frame.size.width - (view.safeAreaInsets.left * 1.5)) {
pageTransition(animated: true, direction: "fromRight")
} else if (location.x < (view.safeAreaInsets.left * 1.5)) {
pageTransition(animated: true, direction: "fromLeft")
}
}
else {
if (location.x > self.view.frame.size.width - 40) {
pageTransition(animated: true, direction: "fromRight")
} else if (location.x < 40) {
pageTransition(animated: true, direction: "fromLeft")
}
}
}
}
}
func pageTransition(animated: Bool, direction: String) {
let result = loadData(fileName: pagesData)
switch direction {
case "fromRight":
pageIndex += 1
case "fromLeft":
pageIndex -= 1
default: break
}
pageViews[0].pageIndex = pageIndex
pageViews[1].pageIndex = pageIndex
if pageIndex <= -1 {
pageIndex = 0
} else if pageIndex >= result.pagesData.count {
pageIndex = result.pagesData.count - 1
finishReading()
} else {
let fromView = pageViews[0].isHidden ? pageViews[1] : pageViews[0]
let toView = pageViews[0].isHidden ? pageViews[0] : pageViews[1]
toView.configure(theData: result.pagesData[pageIndex])
if animated {
toView.isHidden = false
let animation = CATransition()
animation.duration = 0
animation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
animation.isRemovedOnCompletion = true
animation.subtype = direction
let tapAnimationType = "fade"
switch tapAnimationType {
case "pageCurl": animation.type = "pageCurl"
case "fade": animation.type = "fade"
case "moveIn": animation.type = "moveIn"
case "push": animation.type = "push"
case "reveal": animation.type = "reveal"
default: animation.type = "fade" }
self.pageContainer.layer.add(animation, forKey: "pageAnimation")
self.pageContainer.bringSubview(toFront: toView)
}
else {
fromView.isHidden = true
toView.isHidden = false
}
}
}
}
page layout:
class PageLayout: UIView {
var imageArray: [UIImage] = []
var index = Int()
var pageIndex = Int()
var imageDirection = ""
var imageViewTopConstraint = NSLayoutConstraint()
var imageViewBottomConstraint = NSLayoutConstraint()
var imageViewLeadingConstraint = NSLayoutConstraint()
var imageViewTrailingConstraint = NSLayoutConstraint()
private let imageView: UIImageView = {
let image = UIImageView()
image.contentMode = .scaleAspectFill
image.translatesAutoresizingMaskIntoConstraints = false
return image
}()
private let textLabel: UILabel = {
let label = UILabel()
label.translatesAutoresizingMaskIntoConstraints = false
return label
}()
let screenWidth = UIScreen.main.bounds.size.width
override init(frame: CGRect) {
super.init(frame: frame)
setupViews()
}
required init?(coder: NSCoder) {
fatalError("Not happening")
}
func setupViews() {
addSubview(imageView)
addSubview(textLabel)
}
func setupConstraints() {
let scenes = UIApplication.shared.connectedScenes
let windowScene = scenes.first as? UIWindowScene
let window = windowScene?.windows.first
let safeArea = window?.safeAreaInsets
textLabel.leadingAnchor.constraint(equalTo: leadingAnchor, constant: safeArea!.left+16.0).isActive = true
textLabel.trailingAnchor.constraint(equalTo: trailingAnchor, constant: -safeArea!.right-16.0).isActive = true
textLabel.centerXAnchor.constraint(equalTo: centerXAnchor).isActive = true
textLabel.centerYAnchor.constraint(equalTo: centerYAnchor).isActive = true
removeConstraints([imageViewTopConstraint, imageViewBottomConstraint, imageViewLeadingConstraint,
imageViewTrailingConstraint])
switch imageDirection {
case "left":
imageViewTopConstraint = imageView.topAnchor.constraint(equalTo: topAnchor, constant: 0.0)
imageViewBottomConstraint = imageView.bottomAnchor.constraint(equalTo: bottomAnchor, constant: 0.0)
imageViewLeadingConstraint = imageView.leadingAnchor.constraint(equalTo: leadingAnchor, constant: -20.0)
imageViewTrailingConstraint = imageView.trailingAnchor.constraint(equalTo: trailingAnchor, constant: 0.0)
addConstraints([imageViewTopConstraint, imageViewBottomConstraint, imageViewLeadingConstraint, imageViewTrailingConstraint])
imageView.layer.removeAllAnimations()
imageView.transform = CGAffineTransformTranslate(.identity, 0, 0)
UIView.animate(withDuration: 4.0, delay: 0, animations: {
self.imageView.transform = CGAffineTransformTranslate(.identity, 20, 0)
}, completion: nil)
case "right":
imageViewTopConstraint = imageView.topAnchor.constraint(equalTo: topAnchor, constant: 0.0)
imageViewBottomConstraint = imageView.bottomAnchor.constraint(equalTo: bottomAnchor, constant: 0.0)
imageViewLeadingConstraint = imageView.leadingAnchor.constraint(equalTo: leadingAnchor, constant: 0.0)
imageViewTrailingConstraint = imageView.trailingAnchor.constraint(equalTo: trailingAnchor, constant: 20.0)
addConstraints([imageViewTopConstraint, imageViewBottomConstraint, imageViewLeadingConstraint, imageViewTrailingConstraint])
imageView.layer.removeAllAnimations()
imageView.transform = CGAffineTransformTranslate(.identity, 0, 0)
UIView.animate(withDuration: 4.0, delay: 0, animations: {
self.imageView.transform = CGAffineTransformTranslate(.identity, -20, 0)
}, completion: nil)
default: break
}
}
func configure(theData: PageData) {
textLabel.text = theData.textData
imageDirection = theData.imageDirection
imageView.image = imageArray[pageIndex]
setupConstraints()
}
}
other:
struct PagesData: Decodable {
var pagesData: [PageData]
}
struct PageData: Decodable {
let textData, imageDirection: String
}
JSON:
{
"pagesData" : [
{
"textData" : "1",
"imagePosition" : "left",
},
{
"textData" : "2",
"imagePosition" : "left",
},
{
"textData" : "3",
"imagePosition" : "right",
},
{
"textData" : "4",
"imagePosition" : "right",
},
]
}
What I have:
All works fine when I turn the page and wait for the animation finished. But when I not wait for the animation finished and go to next page I see that current page with image jumps quickly to 0 and next I see animation for next page.
What I want:
when I not wait for the animation of current page finished and go to next page I can't see the current page jumps to 0. I want to see smoothly flip
Video to reproduce the problem:
At this video I always go to next page not wait for the animation of current page finished. For first, second and third pages all works fine but for next images I have a problems
https://drive.google.com/file/d/1cms3G_o8W8bdGj9t5gAnItPvzFN7Z3mG/view?usp=sharing
Git:
Thank you for providing a sample project!
The answer was quite simple, but a lot easier to see (and test) with the project (:
In your pageTransition(args) you forgot to set fromView.isHidden = true at the end of the animation. E.g.:
if animated {
//Animation setup (your code) including unhiding 'toView'
fromView.isHidden = true // here
} else {
toView.isHidden = false
fromView.isHidden = true
}
This was causing you to display the same view over and over and removing the residual animation caused the snapping effect.