IOS swift scrollview programmatically - ios

I am implementing a scrollview with multiple views in it programmatically. When I add subviews to it, they are not been displayed.

Here is a full example of adding 3 UIView subviews to a UIScrollView, using constraints to define the scroll view's .contentSize.
You can run this directly in a Playground page - including the ability to scroll:
import UIKit
import PlaygroundSupport
class TestViewController : UIViewController {
let redView: UIView = {
let v = UIView()
v.backgroundColor = .red
v.translatesAutoresizingMaskIntoConstraints = false
return v
}()
let greenView: UIView = {
let v = UIView()
v.backgroundColor = .green
v.translatesAutoresizingMaskIntoConstraints = false
return v
}()
let blueView: UIView = {
let v = UIView()
v.backgroundColor = .blue
v.translatesAutoresizingMaskIntoConstraints = false
return v
}()
let scrollView: UIScrollView = {
let v = UIScrollView()
v.translatesAutoresizingMaskIntoConstraints = false
v.backgroundColor = .cyan
return v
}()
override func viewDidLoad() {
super.viewDidLoad()
// add the scroll view to self.view
self.view.addSubview(scrollView)
// constrain the scroll view to 8-pts on each side
scrollView.leftAnchor.constraint(equalTo: view.leftAnchor, constant: 8.0).isActive = true
scrollView.topAnchor.constraint(equalTo: view.topAnchor, constant: 8.0).isActive = true
scrollView.rightAnchor.constraint(equalTo: view.rightAnchor, constant: -8.0).isActive = true
scrollView.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -8.0).isActive = true
// add three views to the scroll view
scrollView.addSubview(redView)
scrollView.addSubview(greenView)
scrollView.addSubview(blueView)
// give each view a height of 300
NSLayoutConstraint.activate([
redView.heightAnchor.constraint(equalToConstant: 300),
greenView.heightAnchor.constraint(equalToConstant: 300),
blueView.heightAnchor.constraint(equalToConstant: 300),
])
// give each view a width constraint equal to scrollView's width
NSLayoutConstraint.activate([
redView.widthAnchor.constraint(equalTo: scrollView.widthAnchor),
greenView.widthAnchor.constraint(equalTo: scrollView.widthAnchor),
blueView.widthAnchor.constraint(equalTo: scrollView.widthAnchor),
])
// constrain each view's leading and trailing to the scrollView
// this also defines the width of the scrollView's .contentSize
NSLayoutConstraint.activate([
redView.leadingAnchor.constraint(equalTo: scrollView.leadingAnchor),
greenView.leadingAnchor.constraint(equalTo: scrollView.leadingAnchor),
blueView.leadingAnchor.constraint(equalTo: scrollView.leadingAnchor),
redView.trailingAnchor.constraint(equalTo: scrollView.trailingAnchor),
greenView.trailingAnchor.constraint(equalTo: scrollView.trailingAnchor),
blueView.trailingAnchor.constraint(equalTo: scrollView.trailingAnchor),
])
// constrain redView's Top to scrollView's Top + 8-pts padding
// this also defines the Top of the scrollView's .contentSize
NSLayoutConstraint.activate([
redView.topAnchor.constraint(equalTo: scrollView.topAnchor, constant: 8.0),
])
// constrain greenView's Top to redView's Bottom + 20-pts spacing
NSLayoutConstraint.activate([
greenView.topAnchor.constraint(equalTo: redView.bottomAnchor, constant: 20.0),
])
// constrain blueView's Top to greenView's Bottom + 20-pts spacing
NSLayoutConstraint.activate([
blueView.topAnchor.constraint(equalTo: greenView.bottomAnchor, constant: 20.0),
])
// constrain blueView's Bottom to scrollView's Bottom + 8-pts padding
// this also defines the Bottom / Height of the scrollView's .contentSize
// Note: it must be negative
NSLayoutConstraint.activate([
blueView.bottomAnchor.constraint(equalTo: scrollView.bottomAnchor, constant: -8.0),
])
// result:
// scrollView's .contentSize.width is now
// scrollView's width (defined by subviews' leading and trailing anchors
//
// and scrollView's .contentSize.height is now
// redView-Height + 20-pts-spacing +
// greenView-Height + 20-pts-spacing +
// blueView-Height +
// 8-pts top-padding + 8-pts bottom-padding
// or 956
}
}
let vc = TestViewController()
vc.view.backgroundColor = .yellow
PlaygroundPage.current.liveView = vc

Related

iOS: How to scroll navigation bar as view controller scrolls

I want to scroll the navigation bar as the user scrolls on the view controller. This should be similar to how the YouTube app's home page is working. When the user scrolls down, the navigation bar should be made visible. The navigation bar should move as much as the scroll amount.
I'm aware of hidesBarOnSwipe and setNavigationBarHidden, but these do not give precise control of the y-axis. I'm also reading that Apple does not support directly modifying the navigation bar frame.
So, how does YouTube do this? I'm looking for an MVP demonstrating navigation bar position change along with a UIScrollView offset change.
Without additional detail about what you want to do, I'll make some guesses.
First, the top of the YouTube app's home page is almost certainly not a UINavigationBar -- it doesn't behave like one, there is no pushing/popping of controllers going on, it's in a tab bar controller setup, etc.
So, let's assume it's a view with subviews - we'll call it a "sliding header view" - and your goal is:
don't let the header view's top scroll down
"push it up" when scrolling up
"pull it down" when scrolling down
We can accomplish this by constraining the Top of that header view to the Top of the scroll view's Frame Layout Guide.
when we start to scroll, we'll save the current .contentOffset.y
when we scroll, we'll get the relative scroll y distance
if we're scrolling Up, we'll change the Top Constraint .constant value to move the header view up
if we're scrolling Down, we'll change the Top Constraint .constant value to move the header view down
Here's how it will look at the start:
as we scroll up just a little:
after we've scrolled up farther:
as we scroll down just a little:
after we've scrolled down farther:
Here's the example code for that:
Simple two-label "header" view
class SlidingHeaderView: UIView {
// simple view with two labels
override init(frame: CGRect) {
super.init(frame: frame)
commonInit()
}
required init?(coder: NSCoder) {
super.init(coder: coder)
commonInit()
}
func commonInit() {
backgroundColor = .systemBlue
let v1 = UILabel()
v1.translatesAutoresizingMaskIntoConstraints = false
v1.text = "Label 1"
v1.backgroundColor = .yellow
addSubview(v1)
let v2 = UILabel()
v2.translatesAutoresizingMaskIntoConstraints = false
v2.text = "Label 2"
v2.backgroundColor = .yellow
addSubview(v2)
NSLayoutConstraint.activate([
v1.leadingAnchor.constraint(equalTo: leadingAnchor, constant: 12.0),
v1.trailingAnchor.constraint(equalTo: trailingAnchor, constant: -12.0),
v2.leadingAnchor.constraint(equalTo: leadingAnchor, constant: 12.0),
v2.trailingAnchor.constraint(equalTo: trailingAnchor, constant: -12.0),
v1.topAnchor.constraint(equalTo: topAnchor, constant: 8.0),
v2.bottomAnchor.constraint(equalTo: bottomAnchor, constant: -8.0),
v2.topAnchor.constraint(equalTo: v1.bottomAnchor, constant: 4.0),
v2.heightAnchor.constraint(equalTo: v1.heightAnchor),
])
}
}
example view controller
class SlidingHeaderViewController: UIViewController {
let scrollView: UIScrollView = {
let v = UIScrollView()
v.contentInsetAdjustmentBehavior = .never
return v
}()
let slidingHeaderView: SlidingHeaderView = {
let v = SlidingHeaderView()
return v
}()
let contentView: UIView = {
let v = UIView()
v.backgroundColor = .systemYellow
return v
}()
// Top constraint for the slidingHeaderView
var slidingViewTopC: NSLayoutConstraint!
// to track the scroll activity
var curScrollY: CGFloat = 0
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = .systemBackground
[scrollView, slidingHeaderView, contentView].forEach { v in
v.translatesAutoresizingMaskIntoConstraints = false
}
// add contentView and slidingHeaderView to the scroll view
[contentView, slidingHeaderView].forEach { v in
scrollView.addSubview(v)
}
// add scroll view to self.view
view.addSubview(scrollView)
let safeG = view.safeAreaLayoutGuide
let contentG = scrollView.contentLayoutGuide
let frameG = scrollView.frameLayoutGuide
// we're going to change slidingHeaderView's Top constraint relative to the Top of the scroll view FRAME
slidingViewTopC = slidingHeaderView.topAnchor.constraint(equalTo: frameG.topAnchor, constant: 0.0)
NSLayoutConstraint.activate([
// scroll view Top to view Top
scrollView.topAnchor.constraint(equalTo: safeG.topAnchor, constant: 0.0),
// scroll view Leading/Trailing/Bottom to safe area
scrollView.leadingAnchor.constraint(equalTo: safeG.leadingAnchor, constant: 0.0),
scrollView.trailingAnchor.constraint(equalTo: safeG.trailingAnchor, constant: 0.0),
scrollView.bottomAnchor.constraint(equalTo: safeG.bottomAnchor, constant: 0.0),
// constrain slidingHeaderView Top to scroll view's FRAME
slidingViewTopC,
// slidingHeaderView to Leading/Trailing of scroll view FRAME
slidingHeaderView.leadingAnchor.constraint(equalTo: frameG.leadingAnchor, constant: 0.0),
slidingHeaderView.trailingAnchor.constraint(equalTo: frameG.trailingAnchor, constant: 0.0),
// no Height or Bottom constraint for slidingHeaderView
// content view Top/Leading/Trailing/Bottom to scroll view's CONTENT GUIDE
contentView.topAnchor.constraint(equalTo: contentG.topAnchor, constant: 0.0),
contentView.leadingAnchor.constraint(equalTo: contentG.leadingAnchor, constant: 0.0),
contentView.trailingAnchor.constraint(equalTo: contentG.trailingAnchor, constant: 0.0),
contentView.bottomAnchor.constraint(equalTo: contentG.bottomAnchor, constant: 0.0),
// content view Width to scroll view's FRAME
contentView.widthAnchor.constraint(equalTo: frameG.widthAnchor, constant: 0.0),
])
// add some content to the content view so we have something to scroll
addSomeContent()
// because we're going to track the scroll offset
scrollView.delegate = self
}
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
if slidingHeaderView.frame.height == 0 {
// get the size of the slidingHeaderView
let sz = slidingHeaderView.systemLayoutSizeFitting(CGSize(width: scrollView.frame.width, height: .greatestFiniteMagnitude), withHorizontalFittingPriority: .required, verticalFittingPriority: .defaultLow)
// use its Height for the scroll view's Top contentInset
scrollView.contentInset = UIEdgeInsets(top: sz.height, left: 0, bottom: 0, right: 0)
}
}
func addSomeContent() {
// create a vertical stack view with a bunch of labels
// and add it to our content view so we have something to scroll
let stack = UIStackView()
stack.axis = .vertical
stack.spacing = 32
stack.backgroundColor = .gray
stack.translatesAutoresizingMaskIntoConstraints = false
for i in 1...20 {
let v = UILabel()
v.text = "Label \(i)"
v.backgroundColor = UIColor(white: 0.9, alpha: 1.0)
v.heightAnchor.constraint(equalToConstant: 48.0).isActive = true
stack.addArrangedSubview(v)
}
contentView.addSubview(stack)
NSLayoutConstraint.activate([
stack.topAnchor.constraint(equalTo: contentView.topAnchor, constant: 16.0),
stack.leadingAnchor.constraint(equalTo: contentView.leadingAnchor, constant: 16.0),
stack.trailingAnchor.constraint(equalTo: contentView.trailingAnchor, constant: -16.0),
stack.bottomAnchor.constraint(equalTo: contentView.bottomAnchor, constant: -16.0),
])
}
}
extension SlidingHeaderViewController: UIScrollViewDelegate {
func scrollViewWillBeginDragging(_ scrollView: UIScrollView) {
curScrollY = scrollView.contentOffset.y
}
func scrollViewDidScroll(_ scrollView: UIScrollView) {
let diffY = scrollView.contentOffset.y - curScrollY
var newY: CGFloat = slidingViewTopC.constant - diffY
if diffY < 0 {
// we're scrolling DOWN
newY = min(newY, 0.0)
} else {
// we're scrolling UP
if scrollView.contentOffset.y <= -slidingHeaderView.frame.height {
newY = 0.0
} else {
newY = max(-slidingHeaderView.frame.height, newY)
}
}
// update slidingHeaderView Top constraint constant
slidingViewTopC.constant = newY
curScrollY = scrollView.contentOffset.y
}
}
Everything is done via code - no #IBOutlet or #IBAction connections needed.

(Swift 5) UIScrollView scrolls but none of the content scrolls (video included)

I'm trying to learn to build views without storyboard. I tried to build a scrollview. On that scrollview is a UISearchBar, a UIImageView with an image and a UILabel. It works but none of the content moves. The content is all just frozen in place like no matter how far I scroll the search bar will always be on top of the page. and the image on the bottom. I've attached a video to show what I mean. There's also a problem because none of the content is where I want it to be but that's another problem. I realize this is probably because I don't know enough about constraints and autolayout and building views without storyboards.
Here's the video
class HomePageViewController: UIViewController {
var searchedText: String = ""
let label = UILabel()
let searchBar: UISearchBar = {
let searchBar = UISearchBar()
searchBar.placeholder = "Where are you going?"
searchBar.translatesAutoresizingMaskIntoConstraints = false
searchBar.barTintColor = .systemCyan
searchBar.searchTextField.backgroundColor = .white
searchBar.layer.cornerRadius = 5
return searchBar
}()
let homeImage: UIImageView = {
let homeImage = UIImageView()
homeImage.translatesAutoresizingMaskIntoConstraints = false
homeImage.clipsToBounds = true
return homeImage
}()
let scrollView: UIScrollView = {
let scrollView = UIScrollView()
scrollView.translatesAutoresizingMaskIntoConstraints = false
scrollView.backgroundColor = .systemMint
scrollView.contentSize = CGSize(width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height * 30)
return scrollView
}()
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = .systemPink
// setupLayout()
// tried this here doesn't do anything for me
}
func setupLayout() {
view.addSubview(scrollView)
self.scrollView.addSubview(searchBar)
homeImage.image = UIImage(named: "Treehouse")
self.scrollView.addSubview(homeImage)
label.text = "Inspiration for your next trip..."
self.scrollView.addSubview(label)
// not sure where this label is being added I want it to be underneath the image but it isn't t
let safeG = view.safeAreaLayoutGuide
let viewFrame = view.bounds
NSLayoutConstraint.activate([
scrollView.topAnchor.constraint(equalTo: view.topAnchor, constant: -10),
scrollView.leftAnchor.constraint(equalTo: view.leftAnchor),
scrollView.rightAnchor.constraint(equalTo: view.rightAnchor),
scrollView.bottomAnchor.constraint(equalTo: view.bottomAnchor),
searchBar.topAnchor.constraint(equalTo: safeG.topAnchor, constant: 50.0),
searchBar.widthAnchor.constraint(equalTo: safeG.widthAnchor, multiplier: 0.9),
searchBar.centerXAnchor.constraint(equalTo: safeG.centerXAnchor),
homeImage.topAnchor.constraint(equalTo: safeG.topAnchor, constant: 150),
homeImage.widthAnchor.constraint(equalTo: safeG.widthAnchor, multiplier: 1.1),
homeImage.centerXAnchor.constraint(equalTo: safeG.centerXAnchor),
homeImage.heightAnchor.constraint(equalToConstant: viewFrame.height/2),
label.topAnchor.constraint(equalTo: homeImage.bottomAnchor, constant: 100)
])
// was doing all this in viewDidLayoutSubviews but not sure if this is better place for it
}
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
setupLayout()
// tried this in viewDidLoad() and it didn't solve it.
}
}
any help would be appreciated
First, when constraining subviews in a UIScrollView, you should constrain them to the scroll view's Content Layout Guide. You're constraining them to the view's safe area layout guide, so they're never going to go anywhere.
Second, it's difficult to center subviews in a scroll view, because the scroll view can scroll both horizontally and vertically. So it doesn't really have a "center."
You can either put subviews in a stack view, or, quite common, use a UIView as a "content" view to hold the subviews. If you constrain that content view's Width to the scroll view's Frame Layout Guide width, you can then horizontally center the subviews.
Third, it can be very helpful to comment your constraints, so you know exactly what you expect them to do.
Here's a modified version of your posted code:
class HomePageViewController: UIViewController {
var searchedText: String = ""
let label: UILabel = {
let v = UILabel()
v.translatesAutoresizingMaskIntoConstraints = false
return v
}()
let searchBar: UISearchBar = {
let searchBar = UISearchBar()
searchBar.placeholder = "Where are you going?"
searchBar.translatesAutoresizingMaskIntoConstraints = false
searchBar.barTintColor = .systemCyan
searchBar.searchTextField.backgroundColor = .white
searchBar.layer.cornerRadius = 5
return searchBar
}()
let homeImage: UIImageView = {
let homeImage = UIImageView()
homeImage.translatesAutoresizingMaskIntoConstraints = false
homeImage.clipsToBounds = true
return homeImage
}()
let scrollView: UIScrollView = {
let scrollView = UIScrollView()
scrollView.translatesAutoresizingMaskIntoConstraints = false
scrollView.backgroundColor = .systemMint
// don't do this
//scrollView.contentSize = CGSize(width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height * 30)
return scrollView
}()
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = .systemPink
setupLayout()
}
func setupLayout() {
view.addSubview(scrollView)
//homeImage.image = UIImage(named: "Treehouse")
homeImage.image = UIImage(named: "natureBKG")
label.text = "Inspiration for your next trip..."
// let's use a UIView to hold the "scroll content"
let contentView = UIView()
contentView.translatesAutoresizingMaskIntoConstraints = false
// give it a green background so we can see it
contentView.backgroundColor = .green
contentView.addSubview(searchBar)
contentView.addSubview(homeImage)
contentView.addSubview(label)
scrollView.addSubview(contentView)
let safeG = view.safeAreaLayoutGuide
let svContentG = scrollView.contentLayoutGuide
let svFrameG = scrollView.frameLayoutGuide
NSLayoutConstraint.activate([
// constrain scrollView to all 4 sides of view
// (generally, constrain to safe-area, but this is what you had)
scrollView.topAnchor.constraint(equalTo: view.topAnchor),
scrollView.leftAnchor.constraint(equalTo: view.leftAnchor),
scrollView.rightAnchor.constraint(equalTo: view.rightAnchor),
scrollView.bottomAnchor.constraint(equalTo: view.bottomAnchor),
// constrain contentView to all 4 sides of scroll view's Content Layout Guide
contentView.topAnchor.constraint(equalTo: svContentG.topAnchor, constant: 0.0),
contentView.leadingAnchor.constraint(equalTo: svContentG.leadingAnchor, constant: 0.0),
contentView.trailingAnchor.constraint(equalTo: svContentG.trailingAnchor, constant: 0.0),
contentView.bottomAnchor.constraint(equalTo: svContentG.bottomAnchor, constant: 0.0),
// constrain contentView Width equal to scroll view's Frame Layout Guide Width
contentView.widthAnchor.constraint(equalTo: svFrameG.widthAnchor),
// constrain searchBar Top to contentView Top + 50
searchBar.topAnchor.constraint(equalTo: contentView.topAnchor, constant: 50.0),
// constrain searchBar Width to 90% of contentView Width
searchBar.widthAnchor.constraint(equalTo: contentView.widthAnchor, multiplier: 0.9),
// constrain searchBar centerX to contentView centerX
searchBar.centerXAnchor.constraint(equalTo: contentView.centerXAnchor),
// constrain homeImage Top to searchBar Bottom + 40
homeImage.topAnchor.constraint(equalTo: searchBar.bottomAnchor, constant: 40.0),
// constrain homeImage Width equal to contentView Width
homeImage.widthAnchor.constraint(equalTo: contentView.widthAnchor, multiplier: 1.0),
// constrain homeImage centerX to contentView centerX
homeImage.centerXAnchor.constraint(equalTo: contentView.centerXAnchor),
// constrain homeImage Height to 1/2 of scroll view frame Height
homeImage.heightAnchor.constraint(equalTo: svFrameG.heightAnchor, multiplier: 0.5),
// you probably won't get vertical scrolling yet, so increase the vertical space
// between the homeImage and the label by changing the constant
// from 100 to maybe 400
// constrain label Top to homeImage Bottom + 100
label.topAnchor.constraint(equalTo: homeImage.bottomAnchor, constant: 100.0),
// constrain label centerX to contentView centerX
label.centerXAnchor.constraint(equalTo: contentView.centerXAnchor),
// constrain label Bottom to contentView Bottom - 20
label.bottomAnchor.constraint(equalTo: contentView.bottomAnchor, constant: -20.0),
])
}
}

How to make UIView which is inside scrollview adapt to screen orientation when user changes screen from portrait to landscape in swift

How to make UIView which is inside scrollview adapt to screen orientation when user changes screen from portrait to landscape in swift?
var scrollView: UIScrollView = {
var scroll = UIScrollView()
scroll.translatesAutoresizingMaskIntoConstraints = false
return scroll
}()
view.addSubview(scrollView)
scrollView.topAnchor.constraint(equalTo: view.topAnchor, constant: 100).isActive = true
scrollView.centerXAnchor.constraint(equalTo: view.centerXAnchor, constant: 0).isActive = true
scrollView.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 0).isActive = true
scrollView.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: 0).isActive = true
scrollView.heightAnchor.constraint(equalToConstant: 500).isActive = true
for i in 0..<arr.count {
var contentView = UIView()
contentView.frame = CGRect(x: i * Int(view.bounds.size.width) + 10, y: 0, width: Int(view.bounds.size.width) - 20 , height: Int(view.frame.height))
scrollView.contentSize = CGSize(width: (view.frame.size.width * CGFloat((Double(i)+1))) ,height: scrollView.frame.size.height)
}
Image
You really want to be using auto-layout instead of trying to calculate frame sizes. Let it do all the work for you.
Based on your code, it looks like you want each "contentView" to be the width of the scrollView's frame, minus 20 (so you have 10-pts of space on each side).
You can quite easily do this by embedding your contentViews in a UIStackView.
Here's a simple example:
class ViewController: UIViewController {
var scrollView: UIScrollView = {
var scroll = UIScrollView()
scroll.translatesAutoresizingMaskIntoConstraints = false
return scroll
}()
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(scrollView)
// use a stack view to hold and arrange the scrollView's subviews
let stackView = UIStackView()
stackView.translatesAutoresizingMaskIntoConstraints = false
stackView.spacing = 20
// add the stackView to the scrollView
scrollView.addSubview(stackView)
// respect safe area
let safeG = view.safeAreaLayoutGuide
// use scrollView's Content Layout Guide to define scrollable content
let layoutG = scrollView.contentLayoutGuide
// use scrollView's Frame Layout Guide to define content height (since you want horizontal scrolling)
let frameG = scrollView.frameLayoutGuide
NSLayoutConstraint.activate([
scrollView.topAnchor.constraint(equalTo: safeG.topAnchor, constant: 100),
// you're setting leading and trailing, so no need for centerX
//scrollView.centerXAnchor.constraint(equalTo: view.centerXAnchor, constant: 0),
scrollView.leadingAnchor.constraint(equalTo: safeG.leadingAnchor, constant: 0),
scrollView.trailingAnchor.constraint(equalTo: safeG.trailingAnchor, constant: 0),
// let's constrain the scrollView bottom to the view (safe area) bottom
//scrollView.heightAnchor.constraint(equalToConstant: 500),
scrollView.bottomAnchor.constraint(equalTo: safeG.bottomAnchor, constant: -10.0),
// constrain Top and Bottom of the stackView to scrollView's Content Layout Guide
stackView.topAnchor.constraint(equalTo: layoutG.topAnchor),
stackView.bottomAnchor.constraint(equalTo: layoutG.bottomAnchor),
// 10-pts space on leading and trailing
stackView.leadingAnchor.constraint(equalTo: layoutG.leadingAnchor, constant: 10.0),
stackView.trailingAnchor.constraint(equalTo: layoutG.trailingAnchor, constant: -10.0),
// constrain stackView's height to scrollView's Frame Layout Guide height
stackView.heightAnchor.constraint(equalTo: frameG.heightAnchor),
])
// add some views to the stack view
let arr: [UIColor] = [
.red, .green, .blue, .yellow, .purple,
]
for i in 0..<arr.count {
let contentView = UIView()
contentView.backgroundColor = arr[i]
stackView.addArrangedSubview(contentView)
// constrain each "contentView" width to scrollView's Frame Layout Guide width minus 20
contentView.widthAnchor.constraint(equalTo: frameG.widthAnchor, constant: -20).isActive = true
// don't do this
//contentView.frame = CGRect(x: i * Int(view.bounds.size.width) + 10, y: 0, width: Int(view.bounds.size.width) - 20 , height: Int(view.frame.height))
// don't do this
//scrollView.contentSize = CGSize(width: (view.frame.size.width * CGFloat((Double(i)+1))) ,height: scrollView.frame.size.height)
}
}
}
Run that and see if that's what you're going for.
You need to add your subviews to the scroll view and setup their constraints - using of an auto-layout. Don't use contentView.frame = CGRect(...) and scrollView.contentSize = CGSize(...).
For example you can change your for-in to this:
Note: this is only example, change your for-in loop to your needs.
for i in 0..<arr.count {
// we need to distinguish the first and last subviews (because different constraints)
let topAnchor = i == 0 ? scrollView.topAnchor : scrollView.subviews.last!
let isLast = i == arr.count - 1
// here we will use a specific height for all subviews except the last one
let subviewHeight = 60
var contentView = UIView()
contentView.translatesAutoresizingMaskIntoConstraints = false
scrollView.addSubview(contentView)
if isLast {
NSLayoutConstraint.activate([
contentView.topAnchor.constraint(equalTo: topAnchor),
contentView.widthAnchor.constraint(equalTo: scrollView.widthAnchor),
contentView.bottomAnchor.constraint(equalTo: scrollView.bottomAnchor),
contentView.centerXAnchor.constraint(equalTo: scrollView.centerXAnchor)
]
} else {
NSLayoutConstraint.activate([
contentView.topAnchor.constraint(equalTo: topAnchor),
contentView.widthAnchor.constraint(equalTo: scrollView.widthAnchor),
contentView.heightAnchor.constraint(equalToConstant: subviewHeight),
contentView.centerXAnchor.constraint(equalTo: scrollView.centerXAnchor)
]
}
}

Using ScrollView with StackView as subview and UIViews as children of StackView

I'm struggling to get my scroll view to work programatically.
I have a view controller that instantiates a UIScrollView with the following constraints
class HomeTabBarController: ViewController {
let homePageView = HomePageView()
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(true)
homePageView.setupHomePage()
view.addSubview(homePageView)
///constraints
homePageView.stackView.widthAnchor.constraint(equalTo: view.widthAnchor).isActive = true
homePageView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
homePageView.topAnchor.constraint(equalTo: view.topAnchor).isActive = true;
homePageView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true;
homePageView.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -83).isActive = true;
}
}
The HomePageView (UIScrollView) has a UIStackView and instantiates 3 more UIViews which are the UIStackView's children. The code and constraints are as follows
class HomePageView: UIScrollView {
var homePageCarrousel: HomePageCarrousel?
var homePageSocial: HomePageSocialUp?
var homePageAboutUs: HomePageAboutUs?
var stackView = UIStackView()
func setupHomePage() {
translatesAutoresizingMaskIntoConstraints = false
homePageCarrousel = HomePageCarrousel()
homePageSocial = HomePageSocialUp()
homePageAboutUs = HomePageAboutUs()
guard let homePageSocial = homePageSocial, let homePageCarrousel = homePageCarrousel, let homePageAboutUs = homePageAboutUs else { return }
homePageSocial.setupSocialHeader()
stackView.addArrangedSubview(homePageSocial)
homePageCarrousel.setupCarrousel()
stackView.addArrangedSubview(homePageCarrousel)
homePageAboutUs.setup()
stackView.addArrangedSubview(homePageAboutUs)
addSubview(stackView)
stackView.translatesAutoresizingMaskIntoConstraints = false
stackView.axis = .vertical
stackView.spacing = 10
setLayout()
}
func setLayout(){
guard let homePageSocial = homePageSocial, let homePageCarrousel = homePageCarrousel, let homePageAboutUs = homePageAboutUs else { return }
///header
homePageSocial.leadingAnchor.constraint(equalTo: stackView.leadingAnchor).isActive = true
homePageSocial.topAnchor.constraint(equalTo: stackView.topAnchor).isActive = true
homePageSocial.trailingAnchor.constraint(equalTo: stackView.trailingAnchor).isActive = true
///carrousel
homePageCarrousel.leadingAnchor.constraint(equalTo: stackView.leadingAnchor, constant: 20).isActive = true
homePageCarrousel.topAnchor.constraint(equalTo: stackView.bottomAnchor, constant: 20).isActive = true
homePageCarrousel.trailingAnchor.constraint(equalTo: stackView.trailingAnchor, constant: -20).isActive = true
///about us
homePageAboutUs.leadingAnchor.constraint(equalTo: stackView.leadingAnchor).isActive = true
homePageAboutUs.topAnchor.constraint(equalTo: homePageCarrousel.bottomAnchor, constant: 10).isActive = true
homePageAboutUs.trailingAnchor.constraint(equalTo: stackView.trailingAnchor).isActive = true
homePageAboutUs.bottomAnchor.constraint(equalTo: stackView.bottomAnchor).isActive = true
///stackview
self.stackView.leadingAnchor.constraint(equalTo: leadingAnchor).isActive = true;
self.stackView.topAnchor.constraint(equalTo: topAnchor).isActive = true;
self.stackView.trailingAnchor.constraint(equalTo: trailingAnchor).isActive = true;
self.stackView.bottomAnchor.constraint(equalTo: bottomAnchor).isActive = true;
}
func dispose() {
homePageSocial = nil
homePageCarrousel = nil
homePageAboutUs = nil
subviews.forEach{$0.removeFromSuperview()}
}
}
Each of the children UIView (homePageSocial, homePageCarrousel and homePageAboutUs) have constraints have also got constraints:
HomePageCarrousel
Loads UIImageView and after adding as subview sets the constraint as
heightAnchor.constraint(equalToConstant: imageView.frame.height).isActive = true
HomePageAboutUs
Has 3 UITextviews (headerText, bodyTextLeft, bodyTextRight)
Header on top, bodytextLeft below it being 50% width of screen x = 0 and bodyTextRight x = width of bodyTextLeft.
Constraints are as follows
heightAnchor.constraint(equalToConstant: headerText.frame.height + bodyTextLeft.frame.height).isActive = true
bodyTextLeft.topAnchor.constraint(equalTo: headerText.bottomAnchor, constant: 15).isActive = true
bodyTextLeft.widthAnchor.constraint(equalToConstant: UIScreen.main.bounds.width / 2).isActive = true
bodyTextRight.topAnchor.constraint(equalTo: headerText.bottomAnchor, constant: 15).isActive = true
bodyTextRight.widthAnchor.constraint(equalToConstant: UIScreen.main.bounds.width / 2).isActive = true
bodyTextRight.leadingAnchor.constraint(equalTo: bodyTextLeft.trailingAnchor).isActive = true
HomePageSocialUp
A basic header with an icon and a constraint of
heightAnchor.constraint(equalToConstant: 325).isActive = true
After all that set I still can't get my ui scroll view to scroll on the y axis leaving my text of homePageAboutUs below the tabBar and off screen.
What am I doing wrong here?
Thanks in advance
First - the main purpose of a UIStackView is to arrange its subviews, so it is wrong to add position constraints to those subviews.
Next, when adding subviews to the "root" view of a controller (such as your scroll view), be sure to constrain them to the Safe Area Layout Guide.
Third, constrain the content of your scroll view to its Content Layout Guide.
I'm kind of taking your descriptions and hoping I'm close to what you're going for here:
and after scrolling down:
Here is your code, modified to produce that result:
class HomeTabBarController: UIViewController {
let homePageView = HomePageView()
override func viewDidLoad() {
super.viewDidLoad()
homePageView.setupHomePage()
view.addSubview(homePageView)
// respect safe area
let g = view.safeAreaLayoutGuide
///constraints
NSLayoutConstraint.activate([
homePageView.leadingAnchor.constraint(equalTo: g.leadingAnchor),
homePageView.topAnchor.constraint(equalTo: g.topAnchor),
homePageView.trailingAnchor.constraint(equalTo: g.trailingAnchor),
homePageView.bottomAnchor.constraint(equalTo: g.bottomAnchor),
])
}
}
class HomePageSocialUp: UIView {
func setupSocialHeader() -> Void {
translatesAutoresizingMaskIntoConstraints = false
backgroundColor = .red
let imgView = UIImageView()
imgView.translatesAutoresizingMaskIntoConstraints = false
addSubview(imgView)
NSLayoutConstraint.activate([
// constrain image view 20-pts on each side
imgView.topAnchor.constraint(equalTo: topAnchor, constant: 20.0),
imgView.leadingAnchor.constraint(equalTo: leadingAnchor, constant: 20.0),
imgView.trailingAnchor.constraint(equalTo: trailingAnchor, constant: -20.0),
imgView.bottomAnchor.constraint(equalTo: bottomAnchor, constant: -20.0),
// Height = 325
imgView.heightAnchor.constraint(equalToConstant: 325.0),
])
if let img = UIImage(named: "myHeaderImage") {
imgView.image = img
}
}
}
class HomePageCarrousel: UIView {
func setupCarrousel() -> Void {
translatesAutoresizingMaskIntoConstraints = false
backgroundColor = .green
let imgView = UIImageView()
imgView.translatesAutoresizingMaskIntoConstraints = false
addSubview(imgView)
NSLayoutConstraint.activate([
// constrain image view 20-pts on each side
imgView.topAnchor.constraint(equalTo: topAnchor, constant: 20.0),
imgView.leadingAnchor.constraint(equalTo: leadingAnchor, constant: 20.0),
imgView.trailingAnchor.constraint(equalTo: trailingAnchor, constant: -20.0),
imgView.bottomAnchor.constraint(equalTo: bottomAnchor, constant: -20.0),
// let's make it 3:2 ratio
imgView.heightAnchor.constraint(equalTo: imgView.widthAnchor, multiplier: 2.0 / 3.0)
])
if let img = UIImage(named: "myCarouselImage") {
imgView.image = img
}
}
}
class HomePageAboutUs: UIView {
let headerText = UILabel()
let bodyTextLeft = UILabel()
let bodyTextRight = UILabel()
func setup() -> Void {
translatesAutoresizingMaskIntoConstraints = false
backgroundColor = .blue
[headerText, bodyTextLeft, bodyTextRight].forEach {
// keep label height to text content
$0.setContentHuggingPriority(.required, for: .vertical)
$0.setContentCompressionResistancePriority(.required, for: .vertical)
// allow word-wrap
$0.numberOfLines = 0
// yellow background
$0.backgroundColor = .yellow
$0.translatesAutoresizingMaskIntoConstraints = false
addSubview($0)
}
NSLayoutConstraint.activate([
// header text 8-pts from Top / Leading / Trailing
headerText.topAnchor.constraint(equalTo: topAnchor, constant: 8.0),
headerText.leadingAnchor.constraint(equalTo: leadingAnchor, constant: 8.0),
headerText.trailingAnchor.constraint(equalTo: trailingAnchor, constant: -8.0),
// left text 8-pts from Bottom of header text, 8-pts Leading
bodyTextLeft.topAnchor.constraint(equalTo: headerText.bottomAnchor, constant: 8.0),
bodyTextLeft.leadingAnchor.constraint(equalTo: leadingAnchor, constant: 8.0),
// right text 8-pts from Bottom of header text, 8-pts Trailing
bodyTextRight.topAnchor.constraint(equalTo: headerText.bottomAnchor, constant: 8.0),
bodyTextRight.trailingAnchor.constraint(equalTo: trailingAnchor, constant: -8.0),
// 8-pts between left and right text
bodyTextRight.leadingAnchor.constraint(equalTo: bodyTextLeft.trailingAnchor, constant: 8.0),
// left and right text equal width
bodyTextLeft.widthAnchor.constraint(equalTo: bodyTextRight.widthAnchor),
// constrain Bottom of both to <= 8 (at least 8-pts
bodyTextLeft.bottomAnchor.constraint(lessThanOrEqualTo: bottomAnchor, constant: -8.0),
bodyTextRight.bottomAnchor.constraint(lessThanOrEqualTo: bottomAnchor, constant: -8.0),
])
headerText.font = .systemFont(ofSize: 20, weight: .regular)
bodyTextLeft.font = .systemFont(ofSize: 16, weight: .regular)
bodyTextRight.font = .systemFont(ofSize: 16, weight: .regular)
// texxt alignment
headerText.textAlignment = .center
bodyTextLeft.textAlignment = .left
bodyTextRight.textAlignment = .right
// some sample text
headerText.text = "This is the text for the About Us Header label. It will, of course, wrap onto multiple lines when needed, and auto-size it's height to fit the text."
bodyTextLeft.text = "Left label with\nembedded newlines\nso we can see it grow\nto fit the text.\nLine 5\nLine 6\nLine 7"
bodyTextRight.text = "Right label will wrap if needed. The one with the most lines will determine the bottom."
}
}
class HomePageView: UIScrollView {
var homePageCarrousel: HomePageCarrousel?
var homePageSocial: HomePageSocialUp?
var homePageAboutUs: HomePageAboutUs?
var stackView = UIStackView()
func setupHomePage() {
translatesAutoresizingMaskIntoConstraints = false
homePageCarrousel = HomePageCarrousel()
homePageSocial = HomePageSocialUp()
homePageAboutUs = HomePageAboutUs()
guard let homePageSocial = homePageSocial, let homePageCarrousel = homePageCarrousel, let homePageAboutUs = homePageAboutUs else { return }
homePageSocial.setupSocialHeader()
stackView.addArrangedSubview(homePageSocial)
homePageCarrousel.setupCarrousel()
stackView.addArrangedSubview(homePageCarrousel)
homePageAboutUs.setup()
stackView.addArrangedSubview(homePageAboutUs)
addSubview(stackView)
stackView.translatesAutoresizingMaskIntoConstraints = false
stackView.axis = .vertical
stackView.spacing = 10
setLayout()
}
func setLayout(){
// constrain stackView to scroll view's Content Layout Guide
let g = self.contentLayoutGuide
///stackview
NSLayoutConstraint.activate([
self.stackView.leadingAnchor.constraint(equalTo: g.leadingAnchor),
self.stackView.topAnchor.constraint(equalTo: g.topAnchor),
self.stackView.trailingAnchor.constraint(equalTo: g.trailingAnchor),
self.stackView.bottomAnchor.constraint(equalTo: g.bottomAnchor),
// stack view width is scroll view's frame layout guide width
stackView.widthAnchor.constraint(equalTo: self.frameLayoutGuide.widthAnchor),
])
}
}

How to add extra padding to UIScrollView on iPad programmatically?

Some of the applications add extra padding on left and right to the UIScrollView instances when the device width is too large.
What's important, content of the UIScrollView is not restricted to fixed width, because user can scroll outside of the content. It looks like it would have contentInset set, which dynamically changes based on superview width. How can I achieve it?
Note
Screen from above is not implemented as a scrolling view, I just wanted to visualize the concept.
If it is an option at all, you can adjust left and right (trailing, leading) autolayout constraints.
The following code creates horizontally scrollable scrollView with two containers in it. The first container contains a subview (red rectangle) with some margins.
Scroll View with container.
//: A UIKit based Playground for presenting user interface
import UIKit
import PlaygroundSupport
class MyViewController : UIViewController {
private let scrollView = UIScrollView()
private let contentView = UIView()
override func loadView() {
let view = UIView()
self.view = view
self.view.backgroundColor = UIColor.white
scrollView.isPagingEnabled = true
scrollView.isScrollEnabled = true
scrollView.isUserInteractionEnabled = true
scrollView.bounces = true
self.view.addSubview(scrollView)
scrollView.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
scrollView.topAnchor.constraint(equalTo: self.view.topAnchor),
scrollView.leftAnchor.constraint(equalTo: self.view.leftAnchor),
scrollView.bottomAnchor.constraint(equalTo: self.view.bottomAnchor),
scrollView.rightAnchor.constraint(equalTo: self.view.rightAnchor)
])
contentView.translatesAutoresizingMaskIntoConstraints = false
contentView.backgroundColor = UIColor(white: 0.9, alpha: 0.9)
scrollView.addSubview(contentView)
let widthAnchor = contentView.widthAnchor.constraint(equalTo: scrollView.widthAnchor)
let heightAnchor = contentView.heightAnchor.constraint(equalTo: scrollView.heightAnchor)
widthAnchor.priority = .defaultLow
heightAnchor.priority = .defaultLow
NSLayoutConstraint.activate([
contentView.topAnchor.constraint(equalTo: scrollView.topAnchor),
contentView.leftAnchor.constraint(equalTo: scrollView.leftAnchor),
contentView.bottomAnchor.constraint(equalTo: scrollView.bottomAnchor),
contentView.rightAnchor.constraint(equalTo: scrollView.rightAnchor),
widthAnchor,
heightAnchor
])
contentView.layer.borderWidth = 1
contentView.layer.borderColor = UIColor.red.cgColor
let containerView1 = UIView()
containerView1.translatesAutoresizingMaskIntoConstraints = false
contentView.addSubview(containerView1)
containerView1.backgroundColor = UIColor(white: 0.4, alpha: 1)
NSLayoutConstraint.activate([
containerView1.topAnchor.constraint(equalTo: contentView.topAnchor),
containerView1.leftAnchor.constraint(equalTo: contentView.leftAnchor),
containerView1.bottomAnchor.constraint(equalTo: contentView.bottomAnchor),
containerView1.widthAnchor.constraint(equalTo: scrollView.widthAnchor)
])
let container1Content = container1ContentView()
containerView1.addSubview(container1Content)
NSLayoutConstraint.activate([
container1Content.topAnchor.constraint(equalTo: containerView1.topAnchor, constant: 44),
container1Content.leftAnchor.constraint(equalTo: containerView1.leftAnchor, constant: 44),
container1Content.rightAnchor.constraint(equalTo: containerView1.rightAnchor, constant: -44),
container1Content.bottomAnchor.constraint(equalTo: containerView1.bottomAnchor, constant: -44)
])
let containerView2 = UIView()
containerView2.translatesAutoresizingMaskIntoConstraints = false
contentView.addSubview(containerView2)
containerView2.backgroundColor = UIColor(white: 0.9, alpha: 1)
NSLayoutConstraint.activate([
containerView2.topAnchor.constraint(equalTo: contentView.topAnchor),
containerView2.leftAnchor.constraint(equalTo: containerView1.rightAnchor),
containerView2.bottomAnchor.constraint(equalTo: contentView.bottomAnchor),
containerView2.rightAnchor.constraint(equalTo: contentView.rightAnchor),
containerView2.widthAnchor.constraint(equalTo: scrollView.widthAnchor)
])
}
private func container1ContentView() -> UIView {
let content = UIView()
content.translatesAutoresizingMaskIntoConstraints = false
content.backgroundColor = UIColor.red
return content
}
}
// Present the view controller in the Live View window
PlaygroundPage.current.liveView = MyViewController()

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