I have a case, there are 2 tableView in 1 UIViewController, how to do when tableView1 is scrolled The position of scroll tableView2 also follows. thank you
You can try
func scrollViewDidScroll(_ scrollView: UIScrollView) {
if self.tableView1 == scrollView {
self.tableView2.contentOffset = scrollView.contentOffset
}
else {
self.tableView1.contentOffset = scrollView.contentOffset
}
}
Related
I have a chat app and I'm trying to show a custom view that I've made when the user scrolls to the top, also hide it if it's on the bottom of tableview. (like whatsapp does it)
To be honest I'm struggling with the logic of show/hide button.
Tried to save the contentOffset.y of my tableview right after I reload the data so I'll know that's the bottom, and if it's smaller to show the custom view, but mainTableView.contentOffset.y it's always 0.
func scrollViewWillBeginDragging(_ scrollView: UIScrollView) {
if (scrollView == mainTableView) {
print(mainTableView.contentOffset.y)
if let point = startingPointForView {
//where var startingPointForView: CGFloat?
// and tried to save it after I reload the data
//self.startingPointForView = self.mainTableView.contentOffset.y
// but it's always 0
}
// Show and hide button logic
}
}
An image of what I m trying to achieve: https://imgur.com/ZkYEi2P
try this code to hide/show custom view according to UIscrollview contentOffset
func scrollViewDidScroll(_ scrollView: UIScrollView) {
let scrollViewContentHeight = scrollView.contentSize.height
let scrollViewHeight = scrollView.frame.height
if scrollView.contentOffset.y < (scrollViewContentHeight - scrollViewHeight){
//Custom view show
}else{
//Custom view Hide
}
}
May be this code will help you
func scrollViewDidScroll(_ scrollView: UIScrollView) {
if scrollView.panGestureRecognizer.translation(in: scrollView).y > 0 {
// down
button.isHidden = false
} else {
// up
button.isHidden = true
}
}
For someone who is looking to hide a button when tableview is scrolling can use below code:
var previousContentOffset: CGFloat = CGFloat()
extension YourViewController: UIScrollViewDelegate{
func scrollViewDidScroll(_ scrollView: UIScrollView) {
if scrollView == self.yourTableView{
let currentContentOffset = scrollView.contentOffset.y
if (currentContentOffset > previousContentOffset) {
// scrolling towards the bottom
if scrollView.contentOffset.y > 50 {
self.yourButton.isHidden = true
} else {
self.yourButton.isHidden = false
}
} else if (currentContentOffset < previousContentOffset) {
// scrolling towards the top
let maximumOffset = scrollView.contentSize.height - scrollView.frame.size.height
// Change 10.0 to adjust the distance from bottom
if maximumOffset - currentContentOffset <= 10.0 {
self.yourButton.isHidden = true
} else {
self.yourButton.isHidden = false
}
}
previousContentOffset = currentContentOffset
}
}
}
I have a VC as shown in the image
It has a UICollectionView on top, and a UITableView at the bottom.
CollectionView has 1:3 of the screen and TableView has 2:3 of the screen(set using equalHeight constraint).
I want to change the height of the UICollectionView when the tableView is scrolled.
When the tableView is scrolled up,I want to change the multiplier of equalHeights constraint to like 1:5 and 4:5 of collectionView and tableView respectively.This will ensure that height of tableView increases and collectionView decreases
When the tableView is scrolled down, the multiplier of equalHeights constraint should reset to default.
I've tried adding swipe and pan gestures to tableView, but they are unrecognised.
How to achieve this functionality?
P.S: Would love to achieve this functionality by using a pan gesture, so that dragging up and down changes the heights progressively.
This is the view hierarchy
EDIT/UPDATE
This is the code that I'm using.
class MyConstant {
var height:CGFloat = 10
}
let myConstant = MyConstant()
MainScreenVC
override func viewWillAppear(_ animated: Bool) {
myConstant.height = self.view.frame.size.height
}
func scrollViewDidScroll(_ scrollView: UIScrollView) {
if (self.lastContentOffset < scrollView.contentOffset.y) {
NotificationCenter.default.post(name: Notifications.decreaseHeightNotification.name, object: nil)
self.topViewConstraint.constant = -self.view.frame.height / 6
UIView.animate(withDuration: 0.3, animations: {
self.view.layoutIfNeeded()
})
} else if (self.lastContentOffset > scrollView.contentOffset.y) {
NotificationCenter.default.post(name: Notifications.increaseHeightNotification.name, object: nil)
self.topViewConstraint.constant = 0
UIView.animate(withDuration: 0.3, animations: {
self.view.layoutIfNeeded()
})
}
self.lastContentOffset = scrollView.contentOffset.y
}
Cell.Swift
override func awakeFromNib() {
super.awakeFromNib()
NotificationCenter.default.addObserver(self, selector: #selector(decreaseHeight), name: Notification.Name("decreaseHeightNotification"), object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(increaseHeight), name: Notification.Name("increaseHeightNotification"), object: nil)
self.contentView.translatesAutoresizingMaskIntoConstraints = false
heightConstraint.constant = (myConstant.height / 3) - 10
widthConstraint.constant = heightConstraint.constant * 1.5
}
#objc func decreaseHeight() {
heightConstraint.constant = (myConstant.height / 6) - 10
widthConstraint.constant = (heightConstraint.constant * 1.5)
self.layoutIfNeeded()
}
#objc func increaseHeight() {
heightConstraint.constant = (myConstant.height / 3) - 10
widthConstraint.constant = (heightConstraint.constant * 1.5)
self.layoutIfNeeded()
}
Now when I scroll both simultaneously, the screen freezes. Also is there a better way of resizing the collectionViewCell size?
I haven't tested it but you can do this. Use Autolayout in this view. it will work better with that.
Set the tableview constraint as Top, Left, Bottom, Right => 0, 0, 0, 0 with the main view and put collectionView under the tableview with constraint as Top,Left,Right, height => 0, 0, 0, x with the main view.
Note: Tableview is on top of the collectionView.
Connect your height constraint outlet of CollectionView and also define your defaultOffset variable
#IBOutlet weak var defaultHeightConstraint: NSLayoutConstraint
var defaultOffSet: CGPoint?
In viewDidLoad,
override func viewDidLoad() {
super.viewDidLoad()
tableView.contentInset = UIEdgeInsetsMake(collectionView.size.height, 0, 0, 0)
}
In viewDidAppear, write
override func viewDidAppear(_ animated: Bool) {
defaultOffSet = tableView.contentOffset
}
In ViewDidScroll
func scrollViewDidScroll(_ scrollView: UIScrollView) {
let offset = tableView.contentOffset
if let startOffset = self.defaultOffSet {
if offset.y < startOffset.y {
// Scrolling down
// check if your collection view height is less than normal height, do your logic.
let deltaY = fabs((startOffset.y - offset.y))
defaultHeightConstraint.constant = defaultHeightConstraint.constant - deltaY
} else {
// Scrolling up
let deltaY = fabs((startOffset.y - offset.y))
defaultHeightConstraint.constant = defaultHeightConstraint.constant + deltaY
}
self.view.layoutIfNeeded()
}
}
Hope it helps.
Since UITableView is a subclass of UIScrollView, your table view's delegate can receive UIScrollViewDelegate methods.
You don't need to use PanGesture
First implement UITableviewDelegate and in that
var oldContentOffset = CGPoint.zero
func scrollViewDidScroll(_ scrollView: UIScrollView) {
let contentOffset = scrollView.contentOffset.y - oldContentOffset.y
if (self.oldContentOffset < scrollView.contentOffset.y) {
// moved to top
} else if (self.oldContentOffset > scrollView.contentOffset.y) {
// moved to bottom
} else {
// didn't move
}
oldContentOffset = scrollView.contentOffset
}
Here you can write you logic to change constant value of your constraint
UPDATE/EDIT
Another thing is don't use multiplier for tabelview height.with collection view it is fine you can give height constraint with self.view in ratio of 1/3 . for tableview just give leading ,trailing top (UICollectionView) and bottom.
So when you change height constant of UICollectionView Tableview height automatically decrease and vice-versa for decrease.
You can not change the multiplier from the outlet as it is read only. so you have to constant value to self.view.frame.height / 3 will work for you
Hope it is helpful to you
For a much cleaner approach, why don't you use a UIScrollView as the container view and add the UICollectionView and UITableView inside it and give the collectionView a height constraint while disabling tableView's scroll till the height constraint of your collectionView becomes 0.
Here's the snippet:
Extend your VC with UIScrollViewDelegate and use:
func scrollViewDidScroll(_ scrollView: UIScrollView) {
if scrollView.contentOffset.y >= 0 && scrollView.contentOffset.y <= yourLimit {
heightConstraint.constant = collectionViewHeight - scrollView.contentOffset.y
tableView.isScrollEnabled = false
} else if scrollView.contentOffset.y > yourLimit {
heightConstraint.constant = collectionViewHeight
tableView.isScrollEnabled = true
}
}
Try this snippet after customizing small things in it. It should work mostly, if it doesn't there is another approach which I'd share once this doesn't work.
Why don't you just add Custom Table Cell with your collection view inside, and when indexPath.row == 0 , return your custom table cell.
I have a VC that contains a collectionView and a scrollView. I put this code to change current page of pageController by scrolling in scrollView :
func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
let pageNumber = round(scrollView.contentOffset.x / scrollView.frame.size.width)
self.pageController.currentPage = Int(pageNumber)
}
It works nice for scrollView but the problem is when i even scroll in collectionView it declares and causes unwanted changing in pageController!
What should i do?
In addition to the answers posted above, You can make use of the tag property of the view.
Just assign a tag (Int) to your scrollview either in xib or via code.
yourScrollView.tag = 10
And in the scrollview delegate method check for this tag:
func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
if scrollView.tag == 10 {
///Your scrollview was scrolled
} else {
// Collection view was scrolled
}
}
if scrollView == yourScrollView{
let pageNumber = round(scrollView.contentOffset.x / scrollView.frame.size.width)
self.pageController.currentPage = Int(pageNumber)
}
check if the instance running the method is actually your scrollView
First you have to understand bit detail about UICollectionView. The UICollectionView is subclassed from UIScrollView. That's why its getting called for both the scrolling (Scrolling collection view and scrolling scroll view). You can do like this to differentiate what type of scrolling it is,
func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
if scrollView == "Your scrollView outlet name" { // Scroll view
let pageNumber = round(scrollView.contentOffset.x / scrollView.frame.size.width)
self.pageController.currentPage = Int(pageNumber)
} else {
// Collection view
}
}
Thanks.
You need to check the scrollView inside the scrollViewDidEndDecelerating if it is your scroll view or your collection view.
Just add an if scrollView == myScrollView before doing the 2 lines of code you have.
Your code shoudl look like this
func
scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
if scrollView == myScrollView {
let pageNumber = round(scrollView.contentOffset.x / scrollView.frame.size.width)
self.pageController.currentPage = Int(pageNumber)
}
}
I want to stop backward scrolling on ScrollView after user scrolls to the next page. How can I do that.
I tried the following two codes, but the first one does not have any effect
self.scrollView.contentOffset = CGPointMake(self.view.frame.width,0)
and the second only disables the forward scrolling.
self.scrollView.contentSize = CGSizeMake( 2 * scrollWidth, scrollHeight);
To disable scrolling in one direction you implement the UIScrollViewDelegate method scrollViewDidScroll and put your logic there. For instance this TableViewController can only ever scroll down, because if the user tries to scroll up, we just overwrite the contentOffset, effectively undoing their scroll before they see it.
class ViewController: UITableViewController {
var lastScrollPosition = CGPoint.zero
override func scrollViewDidScroll(_ scrollView: UIScrollView) {
guard scrollView.contentOffset.y > lastScrollPosition.y else {
scrollView.setContentOffset(lastScrollPosition, animated: false)
return
}
lastScrollPosition = scrollView.contentOffset
}
}
If your cell is equal in size to your screen, you can apply the following option, which is very smooth:
var lastScrollPosition = CGPoint.zero
func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
if scrollView.contentOffset.x == lastScrollPosition.x + UIScreen.main.bounds.width {
lastScrollPosition.x += UIScreen.main.bounds.width
}
}
func scrollViewDidScroll(_ scrollView: UIScrollView) {
guard scrollView.contentOffset.x > lastScrollPosition.x else {
scrollView.setContentOffset(lastScrollPosition, animated: false)
return
}
}
I have a scrollview inside tableview (tableview's header) and I want to call this action when scroll finish:
func scrollViewDidEndDecelerating(scrollView: UIScrollView) {
let pageNumber = round(bookScrollView.contentOffset.x / bookScrollView.frame.size.width)
pageControl.currentPage = Int(pageNumber)
print("scroll")
}
when I scroll bookScrollView nothing happen, but when table view scroll this function run.
How I detect when bookScrollView scroll and run function?
thanks
Here, you can define, scrollOfTable, or you can also define TAG property. identify and only scroll when scrollview comes in, not tableview.
You also need to check, if your scrollView is setting delegate
self.vsScrollView.delegate = self
func scrollViewDidEndDecelerating(scrollView: UIScrollView) {
if scrollView == scrollOfTable {
}
else if scrollView == scrollOfScrollView {
}
else {
//something else
}
}