Let's see how to create a parallax effect in your app.
First, let's define what parallax is. Parallax scrolling is a popular design technique used to create a scrolling effect by moving multiple layers of content at different speeds. It's an effective way to add visual interest and depth to your app or website. You can achieve a similar effect with UIScrollView
. In this blog post, we'll explore how to create a parallax effect using UIScrollView
.
To create a parallax effect with UIScrollView
, we'll use two parallax sub-views. We will adjust their position based on the scroll position of the UIScrollView
.
Step 1: Create the views
First, let's create our views programmatically and set up initial frames/constraints. We can do this in the viewDidLoad()
method of our view controller.
class ViewController: UIViewController, UIScrollViewDelegate {
let scrollView = UIScrollView()
let contentView = UIView()
let parallax1View = UIView()
let parallax2View = UIView()
let parallax3View = UIView()
override func viewDidLoad() {
super.viewDidLoad()
scrollView.delegate = self
scrollView.translatesAutoresizingMaskIntoConstraints = false
view.addSubview(scrollView)
contentView.translatesAutoresizingMaskIntoConstraints = false
scrollView.addSubview(contentView)
parallax1View.frame = CGRect(x: 0, y: 0, width: 200, height: 100)
parallax1View.backgroundColor = .red
parallax1View.clipsToBounds = true
parallax1View.translatesAutoresizingMaskIntoConstraints = false
contentView.addSubview(parallax1View)
parallax2View.frame = CGRect(x: 100, y: 0, width: 200, height: 100)
parallax2View.backgroundColor = .yellow
parallax2View.clipsToBounds = true
parallax2View.translatesAutoresizingMaskIntoConstraints = false
contentView.addSubview(parallax2View)
self.setUpConstraints()
}
func setUpConstraints() {
NSLayoutConstraint.activate([
// Scroll view
scrollView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
scrollView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
scrollView.topAnchor.constraint(equalTo: view.topAnchor),
scrollView.bottomAnchor.constraint(equalTo: view.bottomAnchor),
// Content view
contentView.leadingAnchor.constraint(equalTo: scrollView.leadingAnchor),
contentView.trailingAnchor.constraint(equalTo: scrollView.trailingAnchor),
contentView.topAnchor.constraint(equalTo: scrollView.topAnchor),
contentView.bottomAnchor.constraint(equalTo: scrollView.bottomAnchor),
contentView.widthAnchor.constraint(equalTo: scrollView.widthAnchor),
contentView.heightAnchor.constraint(equalTo: scrollView.heightAnchor, multiplier: 2)
])
}
}
In this code, we create the required views and set up constraints to position and size the views.
Step 2: Adjust parallax sub-view positions
Next, we need to adjust the position of the parallaxImageView
based on the scroll position of the UIScrollView
. We can do this in the scrollViewDidScroll(_:)
method of the UIScrollViewDelegate
protocol.
extension ViewController {
func scrollViewDidScroll(_ scrollView: UIScrollView) {
let yContentOffest = scrollView.contentOffset.y
let ySlowerOffset = yContentOffest / 2
let yFasterOffset = 2 * yContentOffest
parallax1View.frame.origin.y = -ySlowerOffset
parallax2View.frame.origin.y = -yFasterOffset
}
}
In this code, we calculate the vertical offset of the UIScrollView
and adjust the position of the parallax view.
Conclusion
In this blog, we learned how to create a very basic parallax effect using UIScrollView
. We created two views, set up constraints, and adjusted their position based on the scroll position. Now you can use this technique to create stunning parallax effects in your own apps!
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