Swift ScrollView Layout Issue With PageController and Images iOS - ios

Question

I can't figure out how to set constraints for a scrollView with an imageView inside.
I am using the scrollView with a pageConroller to swipe thru a bunch of images.
See my layout in the picture below.
// Code for imageView
for index in 0..<drinksImagesArray.count {
frame.origin.x = scrollView.frame.size.width * CGFloat(index)
frame.size = scrollView.frame.size
let imageView = UIImageView(frame: frame)
imageView.contentMode = .scaleAspectFit
imageView.image = UIImage(named: imagesArray[index].name)
self.scrollView.addSubview(imageView)
}
scrollView.contentSize = CGSize(width: scrollView.frame.size.width * CGFloat(imagesArray.count), height: scrollView.frame.size.height)
scrollView.delegate = self
Any suggestions? Thank you!
Layout

Answer 1

You will have much better luck using auto-layout --- it can handle all of the frame sizes and .contentSize for you.
Here's a quick example - it uses a view controller with a scroll view added in Storyboard, so it should be pretty easy for you to integrate with your code:
class ScrollingImagesViewController: UIViewController {
#IBOutlet var scrollView: UIScrollView!
var drinksImagesArray: [String] = []
override func viewDidLoad() {
super.viewDidLoad()
// however you're populating your array...
drinksImagesArray = [
"drink1",
"drink2",
"drink3",
// etc...
]
// create a horizontal stack view
let stack = UIStackView()
stack.axis = .horizontal
stack.alignment = .fill
stack.distribution = .fillEqually
stack.spacing = 0
// add the stack view to the scroll view
stack.translatesAutoresizingMaskIntoConstraints = false
scrollView.addSubview(stack)
// use scroll view's contentLayoutGuide for content constraints
let svCLG = scrollView.contentLayoutGuide
NSLayoutConstraint.activate([
// stack view constrained Top / Bottom / Leading / Trailing of scroll view CONTENT guide
stack.topAnchor.constraint(equalTo: svCLG.topAnchor),
stack.bottomAnchor.constraint(equalTo: svCLG.bottomAnchor),
stack.leadingAnchor.constraint(equalTo: svCLG.leadingAnchor),
stack.trailingAnchor.constraint(equalTo: svCLG.trailingAnchor),
// stack view height == scroll view FRAME height
stack.heightAnchor.constraint(equalTo: scrollView.frameLayoutGuide.heightAnchor),
])
// create image views and add them to the stack view
drinksImagesArray.forEach { imgName in
let v = UIImageView()
v.backgroundColor = .lightGray
v.contentMode = .scaleAspectFit
// make sure we load a valid image
if let img = UIImage(named: imgName) {
v.image = img
}
stack.addArrangedSubview(v)
}
// stack distribution is set to .fillEqually, so we only need to set the
// width constraint on the first image view
// unwrap it
if let firstImageView = stack.arrangedSubviews.first {
firstImageView.widthAnchor.constraint(equalTo: scrollView.frameLayoutGuide.widthAnchor).isActive = true
}
}
}
Edit
After reviewing your Storyboard...
Auto-layout doesn't seem to like it when you add a UINavigationBar and a UIToolbar and a UIScrollView as subviews. In particular, it appears to confuse the scroll view's frame related constraints.
The fix is to first add constraints for your scroll view:
Top to Navigation Bar Bottom
Bottom to Page Control Top
Leading and Trailing to safe-area
Storyboard / Interface builder will complain that the scroll view is not configured properly. You can either ignore that, or select the scroll view and set Ambiguity to Never Verify:
Then, in your view controller class, we need to create a height constraint for the stack view we're adding to the scroll view, and set that height constant in viewDidLayoutSubviews().
Here's the full code:
//
// WasserhaushaltViewController.swift
// deSynthTheOceans
//
// Created by robinsonhus0 on 24.03.20.
// Copyright © 2020 robinsonhus0. All rights reserved.
//
import UIKit
import AVFoundation
import Charts
import FSCalendar
import HealthKit
struct WasserSpeicher: Codable {
let wassermenge: Double
let speicherdatum: String
let speicherStelle: Double
}
class WasserhaushaltViewController: UIViewController, UIScrollViewDelegate {
#IBOutlet weak var diagrammView: UIView!
#IBOutlet weak var scrollView: UIScrollView!
#IBOutlet weak var pageControl: UIPageControl!
let drinksImagesArray = ["tapWater", "water", "milk", "cola", "coffee", "tea", "juice", "beer"]
var imageIndex = Int()
struct Drinks {
var name: String
var tagesMengeFactor: Double
var gesamtMengeFactor: Double
}
var frame = CGRect(x: 0, y: 0, width: 0, height: 0)
var pageNumber = CGFloat()
#IBOutlet weak var todaysWaterConsumptionLabel: UILabel!
#IBOutlet weak var waterGoalProgress: UIProgressView!
#IBOutlet weak var waterGoalLabel: UILabel!
#IBOutlet weak var wasserMengeStepper: UIStepper!
#IBOutlet weak var motivationTextView: UITextView!
#IBOutlet weak var wasserglasButton: UIBarButtonItem!
#IBOutlet weak var kleineFlascheButton: UIBarButtonItem!
#IBOutlet weak var grosseFlascheButton: UIBarButtonItem!
#IBOutlet weak var overAllWaterConsumptionLabel: UILabel!
// added
let scrollingImagesStackView = UIStackView()
var stackHeightConstraint: NSLayoutConstraint!
override func viewDidLoad() {
super.viewDidLoad()
pageControl.numberOfPages = drinksImagesArray.count
setupDrinkImages()
}
func setupDrinkImages() {
// set stack view properties
scrollingImagesStackView.axis = .horizontal
scrollingImagesStackView.alignment = .fill
scrollingImagesStackView.distribution = .fillEqually
scrollingImagesStackView.spacing = 0
// add the stack view to the scroll view
scrollingImagesStackView.translatesAutoresizingMaskIntoConstraints = false
scrollView.addSubview(scrollingImagesStackView)
// use scroll view's contentLayoutGuide for content constraints
let svCLG = scrollView.contentLayoutGuide
NSLayoutConstraint.activate([
// stack view constrained Top / Bottom / Leading / Trailing of scroll view CONTENT guide
scrollingImagesStackView.topAnchor.constraint(equalTo: svCLG.topAnchor),
scrollingImagesStackView.bottomAnchor.constraint(equalTo: svCLG.bottomAnchor),
scrollingImagesStackView.leadingAnchor.constraint(equalTo: svCLG.leadingAnchor),
scrollingImagesStackView.trailingAnchor.constraint(equalTo: svCLG.trailingAnchor),
])
// create the stack view height constraint - it will be updated in viewDidLayoutSubviews
stackHeightConstraint = scrollingImagesStackView.heightAnchor.constraint(equalToConstant: 0)
stackHeightConstraint.isActive = true
// create image views and add them to the stack view
drinksImagesArray.forEach { imgName in
let v = UIImageView()
v.backgroundColor = .orange
v.contentMode = .scaleAspectFit
// make sure we load a valid image
if let img = UIImage(named: imgName) {
v.image = img
}
scrollingImagesStackView.addArrangedSubview(v)
}
// stack distribution is set to .fillEqually, so we only need to set the
// width constraint on the first image view
// unwrap it
if let firstImageView = scrollingImagesStackView.arrangedSubviews.first {
firstImageView.widthAnchor.constraint(equalTo: scrollView.frameLayoutGuide.widthAnchor).isActive = true
}
scrollView.delegate = self
}
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
// since we have a UINavigationBar and a UIToolBar in the view hierarchy,
// we need to set this here
// Note: if the view size changes
// stack view height == scroll view FRAME height
stackHeightConstraint.constant = scrollView.frame.height
}
// func setupDrinkImages() {
// for index in 0..<drinksImagesArray.count {
// frame.origin.x = scrollView.frame.size.width * CGFloat(index)
// frame.size = scrollView.frame.size
//
// let imageView = UIImageView(frame: frame)
// imageView.contentMode = .scaleAspectFit
// imageView.image = UIImage(named: drinksImagesArray[index])
// self.scrollView.addSubview(imageView)
// }
// scrollView.contentSize = CGSize(width: scrollView.frame.size.width * CGFloat(drinksImagesArray.count), height: scrollView.frame.size.height)
// scrollView.delegate = self
// }
func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
pageNumber = scrollView.contentOffset.x / scrollView.frame.size.width
pageControl.currentPage = Int(pageNumber)
}
}
Your (modified) Storyboard is too big to add here... if you have any trouble with the changes mentioned above, here it is: https://pastebin.com/2Q1uFUgL