I have created two UIScrollViews ( One named scrollView and one named scrollLevel4 )
when I move scrollLevel4, I can get scrollView to move at the same speed using :-
func scrollViewDidScroll(_ scrollLevel4: UIScrollView) {
scrollView.contentOffset.x = scrollLevel4.contentOffset.x
}
However If I want to move scrollView at a different pace, not sure what to do, whenever I add anything to the end of line :
scrollView.contentOffset.x = scrollLevel4.contentOffset.x
it crashes, even a simple + 10, same pace, staggered offset, still crashes
also tried .scrollRectToVisible() method
Thoughts ?
Without seeing the error or your code it's hard to say for sure, but most likely you are setting the same delegate for both scrollViews. When you drag scrollLevel4, it triggers a scroll on scrollView, so you get an infinite loop and eventually a crash.
If you want to use the same delegate on both scrollViews, you'll need to check which one was passed before operating on them. Here's a basic working implementation. Open a new single view project and replace the code in ViewController.swift with:
import UIKit
class ViewController: UIViewController, UIScrollViewDelegate {
var imageView1: UIImageView!
var imageView2: UIImageView!
var scrollView1: UIScrollView!
var scrollView2: UIScrollView!
override func viewDidLoad() {
super.viewDidLoad()
imageView1 = UIImageView(image: UIImage(named: "image.jpg"))
imageView2 = UIImageView(image: UIImage(named: "image.jpg"))
scrollView1 = UIScrollView(frame: CGRect(origin: CGPoint.zero, size: CGSize(width: 200, height: 200)))
scrollView1.contentSize = imageView1.bounds.size
scrollView1.addSubview(imageView1)
view.addSubview(scrollView1)
scrollView2 = UIScrollView(frame: CGRect(origin: CGPoint(x: 0, y: 210), size: CGSize(width: 200, height: 200)))
scrollView2.contentSize = imageView2.bounds.size
scrollView2.addSubview(imageView2)
view.addSubview(scrollView2)
scrollView2.delegate = self
scrollView1.delegate = self
}
func scrollViewDidScroll(_ scrolled: UIScrollView) {
// both scrollViews call this when scrolled, so determine which was scrolled before adjusting
if scrolled === scrollView1 {
scrollView2.contentOffset.x = scrolled.contentOffset.x + 100
} else if scrolled === scrollView2 {
scrollView1.contentOffset.x = scrolled.contentOffset.x - 100
}
}
}
Note that whatever modification you apply to the offset of one, you have to apply the exact inverse (or nothing at all) to the other. Otherwise you'll have an infinite loop of back and forth scrolling ending in a crash.
Related
I would like to have a horizontal scroll layout which displays images. It works fine if setup 0, 0, 0 and 0 the constraints of the UIScrollView. The problem is exactly when I change the constraints to make margins surrounded the UIScrollView. This is what happens:
First image in the UIScrollView
Second image in the UIScrollView
Third image in the UIScrollView
As you can see, each time you scroll, more off-center the current page is.
I have tried to subtract trailing and leading constrains constants to the width of the scrollLayout, play with frames and bouds but without success.
If I run this example in a smaller display like iphone 5S, the problem is more pointed.
class ViewController: UIViewController, UIScrollViewDelegate {
#IBOutlet weak var pageController: UIPageControl!
#IBOutlet weak var scrollView: UIScrollView!
let imagesArray = ["b_1", "b_2", "b_3", "b_4", "b_5"]
override func viewDidLoad() {
super.viewDidLoad()
self.scrollView.isPagingEnabled = true
self.pageController.numberOfPages = imagesArray.count
self.pageController.pageIndicatorTintColor = UIColor.blue
self.pageController.currentPageIndicatorTintColor = UIColor.gray
for i in 0...imagesArray.count - 1{
let imageView = UIImageView()
imageView.contentMode = .scaleToFill
imageView.image = UIImage(named: self.imagesArray[i])
let xPos = CGFloat(i)*self.view.bounds.size.width
imageView.frame = CGRect(x: xPos, y: 0, width: view.frame.size.width, height: self.scrollView.frame.size.height )
self.scrollView.contentSize.width = view.frame.size.width*CGFloat(i+1)
self.scrollView.addSubview(imageView)
}
}
func scrollViewDidScroll(_ scrollView: UIScrollView) {
let page = scrollView.contentOffset.x/scrollView.frame.width
self.pageController.currentPage = Int(page)
}
}
So, I would like to know how to always obtain the current image centered.
Thank you
EDITED with Rajesh results and view debug:
I would recommend using a UICollectionView in place of a UIScrollView - otherwise you will be building a lot of the basics from scratch. You can use a collection view that centers the images, make sure paging is enabled and you should get the interface you're looking for. Make sure to adopt / conform to the UICollectionViewDelegate & UICollectionViewDelegateFlowLayout protocols with your view controller & set those delegates on your collection view. Hope that helps! Best of luck.
Sorry in advance, this is a long question but I wanted to explain as good as I can.
I need to implement a walkthrough(first time launch guide) for the project, which will only be shown to user for the first time they launch the app.
I've implemented it by creating a .xib file, where I was just creating a view for each item I need to implement for the walkthrough by creating objects referring to .xib model.
But now I'm required to implement it without using .xib files, where I need to do it via storyboard. This time I've inserted a scrollView, and then I put another view inside it with the objects I'm going to need such as (labels,imageViews,buttons etc.) But it doesn't work, even though I can create all the objects by copying the view right under the scrollView. When I try to expand the width of the scrollView with all the views created so I can do paging, it doesn't create each view next to each other but only shows me the last object(view) in the simulator as they add up vertically, and I can't do no paging.
Now I provide some sample code to show how I try to implement this:
import UIKit
class DenemeViewController: UIViewController, UIScrollViewDelegate {
#IBOutlet weak var scrollView: UIScrollView!
#IBOutlet weak var pageControl: UIPageControl!
#IBOutlet weak var repeatingView: UIView!
var viewArray = [UIView]()
override func viewDidLoad() {
super.viewDidLoad()
let temporaryView = repeatingView
temporaryView?.backgroundColor = .black
viewArray.append(temporaryView!)
let temporaryViewTwo = repeatingView
temporaryViewTwo?.backgroundColor = .blue
viewArray.append(temporaryViewTwo!)
pageControl.numberOfPages = viewArray.count
pageControl.currentPage = 0
view.bringSubview(toFront: pageControl)
setupScrollView(items: viewArray)
}
func setupScrollView(items: [UIView]) {
scrollView.frame = CGRect(x: 0, y: 0, width: view.frame.width, height: view.frame.height)
scrollView.contentSize = CGSize(width: view.frame.width * CGFloat(items.count), height: view.frame.height)
scrollView.isPagingEnabled = true
for i in 0..<items.count {
items[i].frame = CGRect(x: view.frame.width * CGFloat(i), y: 0, width: view.frame.width, height: view.frame.height)
scrollView.addSubview(items[i])
}
}
func scrollViewDidScroll(_ scrollView: UIScrollView) {
let pageIndex = round(scrollView.contentOffset.x/view.frame.width)
pageControl.currentPage = Int(pageIndex)
}
}
As you can see I first create two different views in viewDidLoad by referring to "repeatingView" which is the outlet of the view inside scrollView on the storyboard. Then I return them in an array and try to implement scrollView's subviews with views.
I was expecting to see the scrollView starting with the view with black background and as I do the paging through right then the view with blue background should appear.
When I run this what I see is only the blue view, and I'm unable to do any paging or scrolling.
I am adding my intro screens in a scrollview.So I have to scroll horizontally only.I have set constraints for scrollview(top, bottom.leading, trailing).I have added subviews like the following
for i in 0..<self.arrIntro.count{
let view = IntroScreenView.instanceFromNib()
let x = CGFloat(i) * self.scrollIntro.frame.size.width
view.frame = CGRect(x: x, y: 0, width: self.scrollIntro.frame.size.width, height: self.scrollIntro.frame.size.height)
print(view,self.scrollIntro)
view.imgIntro.image = UIImage(named: "image-1")//UIImage(contentsOfFile: self.arrIntro[i]["Link"] as! String)
print(self.arrIntro[i]["Link"] as! String)
self.scrollIntro.addSubview(view)
}
self.scrollIntro.contentSize = CGSize(width: (CGFloat(self.arrIntro.count) * self.scrollIntro.frame.size.width ) , height: self.scrollIntro.frame.size.height)
but my scrollview is vertically scrolling little bit.How should I avoid this.Any autolayout issue?
You're not adding any constraints to your views. Add height and width constraints to each item, constraints between the views and constraints from the views to the scroll view. Note that the constraints between the Su views and the scroll view will set the content size for you.
Scroll view scrolls vertically, when contentSize.height is greater than the scrollView height.
Just make sure, your contentSize.height is not greater than the scrollView.frame.size.height.
One reason, that I could guess is that, you might be setting contentSize a point after which the frames of the scroll view changes. You should move setting you contentSize in viewDidLayoutSubviews()
Sample : This code makes vertical scroll
class ViewController: UIViewController, UIScrollViewDelegate {
#IBOutlet var scrollView: UIScrollView!
override func viewDidLoad() {
super.viewDidLoad()
scrollView.contentSize = CGSize(width: self.scrollView.bounds.width*5, height: self.scrollView.frame.height)
}
}
And this does not
class ViewController: UIViewController, UIScrollViewDelegate {
#IBOutlet var scrollView: UIScrollView!
override func viewDidLayoutSubviews() {
scrollView.contentSize = CGSize(width: self.scrollView.bounds.width*5, height: self.scrollView.frame.height)
}
}
I have attached an image here
I am a newbie to iOS development. My question is as follows:
I want to swipe my scrollView outside of its width using gesture control.
To be precise I want my UIScrollView to scroll when swipe is performed in the subview (there is only one subview).
I have gone through several StackOverflow question but I couldn't quite get a correct answer.
Your help is much appreciated!
class ViewController: UIViewController, UIGestureRecognizerDelegate {
#IBOutlet weak var scrollView: UIScrollView!
var images = [UIImageView]()
override func viewDidLoad() {
super.viewDidLoad()
}
override func viewDidAppear(_ animated: Bool) {
var contentWidth: CGFloat = 0.0
for x in 0...2 {
let image = UIImage(named: "icon\(x).png")
let imageView = UIImageView(image:image)
images.append(imageView)
var newX: CGFloat = 0.0
newX = scrollView.frame.size.width/2 + scrollView.frame.size.width * CGFloat(x)
contentWidth += newX
scrollView.addSubview(imageView)
imageView.frame = CGRect(x: newX - 75, y: (scrollView.frame.size.height/2) - 75, width: 150, height: 150)
}
scrollView.clipsToBounds = false
scrollView.contentSize = CGSize(width: contentWidth, height: view.frame.size.height)
}
As you can see in the image the width of my UIScrollView has a grey background color (I did that to illustrate my point). Now I want to also scroll the scroll view when a user swipes in the subview (non-grey) UIImageView.
I have added the following function and made a return of yes to enable both views to recognize gestures simultaneously. But, I am not getting the desired result. Can anyone take a look?
func gestureRecognizer(gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
return true
}
Place view.addGestureRecognizer(scrollView.panGestureRecognizer) in viewDidLoad function.
What it eventually does is it assigns scrollview's gesture recognizer to look for gestures in main view. So it automatically move content of scrollview even when gestures are outside of the scrollview rect.
you can forward touch events in that subview to scrollview. see this answer
I'm a swift newbie. Any help is appreciated.
I have a stack of 10 images. I want the user to be able to swipe up and down to update the the image view to new images.
For example: the Image View starts of by displaying 1.jpg. Then the user gestures down on the Image View and it updates the image to 2.jpg then 3.jpg... etc. depending on how far the gesture is held (kind of like an animation). I am able to update the image by one increment using the following code:
#IBAction func down(sender: UISwipeGestureRecognizer) {
image.image = UIImage(named: "2.jpg")
}
How can I make this a continuous gesture?
The end result should look something like this: https://figure1.com/sections/blog/wp-content/uploads/2014/08/resized.gif
So let's start off first things first.
Based off the idea that this is distance dragged
1) We need a UIScrollView()
2) Set the Scrollview Frame to the frame of the screen
3) Allow use of scrollview delegate, so add UIScrollViewDelegate to the list of subclasses (At the top where it says ClassName: list, of, subclasses, here, separated, by, commas)
4) In your class (If you are in your View Controller class), add the delegate to the scrollview
5) Let's set the contentSize of the scrollView
6) Let's add the images to your view, using a loop
7) Before step 6, make sure that your images are named something with numbers, and the same name, such as Image1 Image2 Image3 so that we can loop through them.
8) Declare a UIImage array
9) I was gonna keep typing steps but here you go :P
class ViewController:UIViewController, UIScrollViewDelegate {
let scrollView = UIScrollView()
let images:[UIImage] = []
let imageView:UIImageView!
override func viewDidLoad() {
//Setting up stuff
for index in 0 ..< 10 {
//It's either %t, %i or %d (I don't recall which is which lol)
images.append(UIImage(named: String(format: "Image %i", index)))
}
imageView = UIImageView(frame: view.bounds)
imageView.contentMode = .ScaleAspectFit
imageView.image = images[0]
imageView.backgroundColor = UIColor.clearColor()
self.view.addSubview(imageView)
scrollView.frame = view.bounds
scrollView.delegate = self
scrollView.backGroundColor = UIColor.clearColor()
//Let's say every time the user drags to 1/10 of the screen, the picture will change
scrollView.contentSize = CGSize(width: self.view.frame.width, height: self.view.frame.height+(self.view.frame*(1/10)*CGFloat(images.count)))
self.view.addSubview(scrollView)
}
//Now let's add some UIScrollView delegates to be called whenever the user scrolls!
func scrollViewDidScroll(scrollView: UIScrollView) {
if(scrollView.contentOffSet.y > self.view.frame.height) {
//(1/10) because we are changing the scrollView every 1/10 of the screen
let pictureCount = scrollView.contentOffset.y/scrollView.frame.height*(1/10)
imageView.image = images[pictureCount]
}
}
}
Don't quote me off this, mainly because I pulled it out of the air, so if it has errors/bugs, I apologize, but feel free to comment and I will try to adjust what is needed.