When I drag section and move of UICollectionView using longPress Gesture then how to auto scroll UICollectionView's scrollview.
Note: in UICollectionView section 0 and 1 not scroll down, onward section only scrolling. 0 and 1 section set as sticky which is not scrolling when I move section.
UnTested Code:
Try this code inside your viewDidload or viewWillAppear.
let indexPath = NSIndexPath(forRow: 10, inSection: 0) // 1
self.collectionView.scrollToItemAtIndexPath(indexPath, atScrollPosition: UICollectionViewScrollPosition.Left, animated: true)
Solved it.
func handleLongGesture(gesture: UILongPressGestureRecognizer) { //dragging Functionality handled here.
let point = gesture.locationInView(self.collectionView)
switch(gesture.state) {
case UIGestureRecognizerState.Changed:
let gesturePoint = gesture.locationInView(self.collectionView)
guard let changeIndexPath = self.collectionView.indexPathForItemAtPoint(gesturePoint)
where changeIndexPath.section > 1 else {
break
}
}
}
Related
I have segmented control as a header of UITableView with cell names. Tableview has different cells with different sizes. When I tap on segment, I do a scroll to specific row in a tableview.
segment.valueSelected = { index in
self.contentTableView.scrollToRow(at: IndexPath(row: index, section: 1), at: .top, animated: true)
}
But how can I change selected index of segmented control when I scroll my tableview? I mean I know how to change index, but the problem is how can I calculate specific offset since all cells has different sizes?
func scrollViewDidScroll(_ scrollView: UIScrollView) {
segment.setSelectIndex(index : ???)
}
Solved by
let visiblerows = contentTableView.indexPathsForVisibleRows
if let lastIndex = visiblerows?.last {
segment.setSelectIndex(index: lastIndex.row, animated: true)
}
I have a collectionView and allow a user to dynamically add cells to the collectionView. The view controller only shows one cell at a time and I want the first textView (which is part of the cell) to become the firstResponder (and keep the keyboard visible at all times), which works fine when loading the view controller (as well as in one of the cases below).
I have created a method to detect the current cell, which I call every time in any of these cases: (1) user scrolls from one cell to another (method placed in scrollViewWillEndDragging), (2) user taps UIButtons to navigate from one cell to another, (3) user taps UIButton to create and append a new cell at the end of the array (which is used by the collectionView).
This is the method:
func setNewFirstResponder() {
let currentIndex = IndexPath(item: currentCardIndex, section: 0)
if let newCell = collectionView.cellForItem(at: currentIndex) as? AddCardCell {
newCell.questionTextView.becomeFirstResponder()
}
}
Now my problem is that this only works in case (1). Apparently I have no cell of type AddCardCell in cases (2) and (3). When I print the currentCardIndex, I get the same result, in all of the cases, which is very confusing.
Any hints why I wouldn't be able to get the cell yet in cases 2 and 3, but I am in case 1?
As a reference here are some of the methods that I am using:
//Update index and labels based on user swiping through card cells
func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
//Update index based on targetContentOffset
let x = targetContentOffset.pointee.x
currentCardIndex = Int(x / view.frame.width)
setNewFirstResponder()
}
And the other method, from which it doesn't work (case 3):
//Method to add a new cell at end of collectionView
#objc func handleAddCell() {
//Inserting a new index path into tableView
let newIndexPath = IndexPath(item: autoSaveCards.count - 1, section: 0)
collectionView.insertItems(at: [newIndexPath])
collectionView.scrollToItem(at: newIndexPath, at: .left, animated: true)
currentCardIndex = autoSaveCards.count - 1
setNewFirstResponder()
}
Regarding case 2,3 i think that the cell is not yet loaded so if let fails , you can try to dispatch that after some time like this , also general note if the cell is not visible then it's nil
DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) {
setNewFirstResponder()
}
Also it can work if you set animated:false to scrollToItem
I created a horizontal tableView, with cells that take up the whole view controller. Instead of scrolling with the default setting, I would like to scroll to the next cell using scrollView.scrollToItem(at: IndexPath method.
Meaning, each time the user scrolls right, it will automatically scroll to the next cell, and each time the user swipes left, it will automatically scroll to the previous cell. Whenever you scroll a direction, it should automatically scroll to the next or previous cell.
I tried intercepting it using scrollViewDidScroll delegate method, but I am running into a ton of problems, it is autoscrolling back and forth and glitching a ton. What am I doing wrong?
var previousOffset: CGFloat = 0.0
var allowHorizontalScroll: Bool = true
func scrollViewDidScroll(_ scrollView: UIScrollView) {
if (allowHorizontalScroll){
let offset = scrollView.contentOffset.x
let diff = previousOffset - offset
previousOffset = offset
var currentBoardIndex = scrollView.indexPathForItem(at: CGPoint(x:offset, y:10))?.item
if currentBoardIndex != nil {
if diff > 0 {
//print("scroll left")
if (currentBoardIndex != 0){
currentBoardIndex = currentBoardIndex! - 1
allowHorizontalScroll = false
scrollView.scrollToItem(at: IndexPath(row: (currentBoardIndex!), section: 0), at: .left, animated: true)
}
}else{
//print("scroll right")
if (currentBoardIndex != ((boardVCDataSource?.fetchedResultsController.fetchedObjects?.count)! - 1)){
currentBoardIndex = currentBoardIndex! + 1
allowHorizontalScroll = false
scrollView.scrollToItem(at: IndexPath(row: (currentBoardIndex!), section: 0), at: .left, animated: true)
}
}
}
}
}
Whenever you scroll a direction, it should automatically scroll to the next or previous cell.
Why not throw out all that code, and instead set your scroll view's isPagingEnabled to true? A paging scroll view does what you describe, automatically.
So I have a collection view of cards, and what I want is when I swipe left I want the next item to be centered in the middle, this doesn't work with paging enabled
So when I swipe left I want the next card to be centered, this doesn't work with the normal behaviour because I just want to swipe one card.
So I have added UISwipeGestureRecognizer and disabled scrolling on the collection view
class ViewController: UIViewController,UICollectionViewDataSource {
#IBOutlet var joke_cards: UICollectionView!
override func viewDidLoad() {
super.viewDidLoad();
//Add gestures
let leftSwipeGest = UISwipeGestureRecognizer(target: self, action: #selector(funcForGesture))
leftSwipeGest.direction = .left
joke_cards.addGestureRecognizer(leftSwipeGest)
}
func funcForGesture(sender: UISwipeGestureRecognizer){
if sender.direction == .left {
//scroll to next item
}
}
Now my problem is how can I scroll to the next item? since I don't know the indexPath? because if I want to use this self.joke_cards.scrollToItem(at: indexPath, at: .centeredHorizontally, animated: true), I will need the index path, so I think I need to figure out the current indexPath on the view and add one when the user swipes.
Any suggestions?
//updated
So I have managed to get it to work, but it only works when I swipe the first time:
func funcForGesture(sender: UISwipeGestureRecognizer){
if sender.direction == .left {
//scroll to next item
let cellItems = self.joke_cards.indexPathsForVisibleItems
let next = cellItems[0] as! IndexPath
self.joke_cards.scrollToItem(at: next, at: .centeredHorizontally, animated: true)
}
}
One solution:
1: Add an NSIndexPath property to your cells and just set the indexPath to the property in your cellForItem method.
2: Get an array of visible cells.
3: Get the rect of the visible cells and calculate their position on the screen and you can allso get the correct indexPath from the cell property.
Second solution:
1: Add a UILongPressGestureRecognizer to your cell contentView
2: Set minimumPressDuration to 0.
3: Add delegate methods to fire acitons or this.
Third solution:
1: Keep your swipe gesture.
2: And use this method (same as option 2) indexPathForItemAtPoint:
Why are you saying that this does not work with paging enabled? This should actually be the best way to do it in my opinion. You can just make the width of the UICollectionViewCells to be equal to the width of the UICollectionView, set the scroll direction to be horizontal and enable paging, that should do the trick.
In this way you won't need any UIGestureRecognizers.
Ok so the solution is this one:
#IBOutlet var joke_cards: UICollectionView!
override func viewDidLoad() {
super.viewDidLoad();
//Add gestures
let leftSwipeGest = UISwipeGestureRecognizer(target: self, action: #selector(funcForGesture))
leftSwipeGest.direction = .left
joke_cards.addGestureRecognizer(leftSwipeGest)
}
func funcForGesture(sender: UISwipeGestureRecognizer){
if sender.direction == .left {
//scroll to next item
let cellItems = self.joke_cards.indexPathsForVisibleItems
self.joke_cards.scrollToItem(at: cellItems.max()!, at: .centeredHorizontally, animated: true)
}
}
using this code to scroll to bottom of collection view. however it scrolls to the second last one only.
private func scrollToBottom() {
let lastSectionIndex = (ChatCollectionView?.numberOfSections())! - 1
let lastItemIndex = (ChatCollectionView?.numberOfItemsInSection(lastSectionIndex))!-1
let indexPath = NSIndexPath(forItem: lastItemIndex, inSection: lastSectionIndex)
ChatCollectionView!.scrollToItemAtIndexPath(indexPath, atScrollPosition: UICollectionViewScrollPosition.Bottom, animated: false)
}
is anyone familiar with a bug like that
Your collection view's frame was under the visible area. You should set its bottom inside visible area.