UIRefreshControl with low height UICollectionView - ios

I have a view which contains another view on the top part, which I'm using to show some basic information. It has about 40% of the total view height. Below that "header" view, I'm using a UICollectionView which is scrollable. Now I've added a UIRefreshControl to my UICollectionView, but refreshing does never occur, because the user can't pull down the UICollectionView that far. When I reduce the height of the top view, it starts working because there's enough space to pull the collectionview down then.
Here's how I'm adding the refreshControl:
self.matchDetailRefreshControl = UIRefreshControl()
self.matchDetailRefreshControl.addTarget(self, action: #selector(MatchDetailViewController.fetchAll), forControlEvents: .ValueChanged)
self.collectionView!.addSubview(self.matchDetailRefreshControl)
self.collectionView!.alwaysBounceVertical = true
Have a look at this screenshot for reference:
As you can see, the UIRefreshControl doesn't get fully filled, while my finger is already at the bottom of the screen.
How can I fix that?

You can implement scrollViewDidScroll.
If the scrollView's contentOffset is past a certain point, then implement your refresh programmatically using beginRefreshing()
eg (with the refresh control connected to an outlet named 'refreshControl')
func scrollViewDidScroll(scrollView: UIScrollView) {
let currentOffset = scrollView.contentOffset
let yOffset = currentOffset.y
if yOffset < -30.0 && !refreshControl.refreshing {
refreshControl.beginRefreshing()
}
}
don't forget to set the scrollView's delegate to self if you haven't already
edit: sorry it's beginRefreshing(), not startRefreshing().

Related

Nested scrollview with Vertical scrolling for both [duplicate]

I need to do this app that has a weird configuration.
As shown in the next image, the main view is a UIScrollView. Then inside it should have a UIPageView, and each page of the PageView should have a UITableView.
I've done all this so far. But my problem is that I want the scrolling to behave naturally.
The next is what I mean naturally. Currently when I scroll on one of the UITableViews, it scrolls the tableview (not the scrollview). But I want it to scroll the ScrollView unless the scrollview cannot scroll cause it got to its top or bottom (In that case I'd like it to scroll the tableview).
For example, let's say my scrollview is currently scrolled to the top. Then I put my finger over the tableview (of the current page being shown) and start scrolling down. I this case, I want the scrollview to scroll (no the tableview). If I keep scrolling down my scrollview and it reaches the bottom, if I remove my finger from the display and put it back over the tebleview and scroll down again, I want my tableview to scroll down now because the scrollview reached its bottom and it's not able to keep scrolling.
Do you guys have any idea about how to implement this scrolling?
I'm REALLY lost with this. Any help will be greatly appreciate it :(
Thanks!
The solution to simultaneously handling the scroll view and the table view revolves around the UIScrollViewDelegate. Therefore, have your view controller conform to that protocol:
class ViewController: UIViewController, UIScrollViewDelegate {
I’ll represent the scroll view and table view as outlets:
#IBOutlet weak var scrollView: UIScrollView!
#IBOutlet weak var tableView: UITableView!
We’ll also need to track the height of the scroll view content as well as the screen height. You’ll see why later.
let screenHeight = UIScreen.mainScreen().bounds.height
let scrollViewContentHeight = 1200 as CGFloat
A little configuration is needed in viewDidLoad::
override func viewDidLoad() {
super.viewDidLoad()
scrollView.contentSize = CGSizeMake(scrollViewContentWidth, scrollViewContentHeight)
scrollView.delegate = self
tableView.delegate = self
scrollView.bounces = false
tableView.bounces = false
tableView.scrollEnabled = false
}
where I’ve turned off bouncing to keep things simple. The key settings are the delegates for the scroll view and the table view and having the table view scrolling being turned off at first.
These are necessary so that the scrollViewDidScroll: delegate method can handle reaching the bottom of the scroll view and reaching the top of the table view. Here is that method:
func scrollViewDidScroll(scrollView: UIScrollView) {
let yOffset = scrollView.contentOffset.y
if scrollView == self.scrollView {
if yOffset >= scrollViewContentHeight - screenHeight {
scrollView.scrollEnabled = false
tableView.scrollEnabled = true
}
}
if scrollView == self.tableView {
if yOffset <= 0 {
self.scrollView.scrollEnabled = true
self.tableView.scrollEnabled = false
}
}
}
What the delegate method is doing is detecting when the scroll view has reached its bottom. When that has happened the table view can be scrolled. It is also detecting when the table view reaches the top where the scroll view is re-enabled.
I created a GIF to demonstrate the results:
Modified Daniel's answer to make it more efficient and bug free.
#IBOutlet weak var scrollView: UIScrollView!
#IBOutlet weak var tableView: UITableView!
#IBOutlet weak var tableHeight: NSLayoutConstraint!
override func viewDidLoad() {
super.viewDidLoad()
//Set table height to cover entire view
//if navigation bar is not translucent, reduce navigation bar height from view height
tableHeight.constant = self.view.frame.height-64
self.tableView.isScrollEnabled = false
//no need to write following if checked in storyboard
self.scrollView.bounces = false
self.tableView.bounces = true
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 20
}
func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
let label = UILabel(frame: CGRect(x: 0, y: 0, width: tableView.frame.width, height: 30))
label.text = "Section 1"
label.textAlignment = .center
label.backgroundColor = .yellow
return label
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
cell.textLabel?.text = "Row: \(indexPath.row+1)"
return cell
}
func scrollViewDidScroll(_ scrollView: UIScrollView) {
if scrollView == self.scrollView {
tableView.isScrollEnabled = (self.scrollView.contentOffset.y >= 200)
}
if scrollView == self.tableView {
self.tableView.isScrollEnabled = (tableView.contentOffset.y > 0)
}
}
Complete project can be seen here:
https://gitlab.com/vineetks/TableScroll.git
After many trials and errors, this is what worked best for me. The solution has to solve two needs 1) determine who's scrolling property should be used; tableView or scrollView? 2) make sure that the tableView doesn't give authority to the scrollView until it has reached the top of it's table/content.
In order to see if the scrollview should be used for scrolling vs the tableview, i checked to see if the UIView right above my tableview was within frame. If the UIView is within frame, it's safe to say the scrollView should have authority to scroll. If the UIView is not within frame, that means that the tableView is taking up the entire window, and therefor should have authority to scroll.
func scrollViewDidScroll(_ scrollView: UIScrollView) {
if scrollView.bounds.intersects(UIView.frame) == true {
//the UIView is within frame, use the UIScrollView's scrolling.
if tableView.contentOffset.y == 0 {
//tableViews content is at the top of the tableView.
tableView.isUserInteractionEnabled = false
tableView.resignFirstResponder()
print("using scrollView scroll")
} else {
//UIView is in frame, but the tableView still has more content to scroll before resigning its scrolling over to ScrollView.
tableView.isUserInteractionEnabled = true
scrollView.resignFirstResponder()
print("using tableView scroll")
}
} else {
//UIView is not in frame. Use tableViews scroll.
tableView.isUserInteractionEnabled = true
scrollView.resignFirstResponder()
print("using tableView scroll")
}
}
hope this helps someone!
None of the answers here worked perfectly for me. Each one had it's owned nuanced problem (needing to do a repeated swipe when one scrollview hit it's bottom, or the scroll indicator not looking correct, etc), so figured I'd throw in another answer.
Ole Begemann has a great write up on doing this exactly https://oleb.net/blog/2014/05/scrollviews-inside-scrollviews/
Despite being an old post, the concepts still apply to the current APIs. Additionally, there is a maintained (Xcode 9 compatible) Objective-C implementation of his approach https://github.com/eyeem/OLEContainerScrollView
If you are facing problem with the nested scrolling issue , here tis the simplest solution for it .
go to your design screen
select your scroll view and then disable bounce on scroll
if your view uses table view inside scroll view then disable bounce on scroll of the table view as well
run and check it is solved
check how to disable bounce on scroll of a scroll view
check how to disable bounce on scroll of a tableview view
I was struggling with this problem, too. There is a very simple solution.
In interface builder:
create simple ViewController
add a simple View, it will be our header, and constrain it to superview
it's the red view on the example below
I have added 12px from top, left and right, and set fixed height to 128px
embed a PageViewController, making sure it is constrained to the superview, and not the header
Now, here comes the fun part: for each page you add, make sure its tableView has an offset from top. Thats it. You can do if with this code, for example (assuming you use UITableViewController as a page):
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
let tables = viewControllers.compactMap { $0 as? UITableViewController }
tables.forEach {
$0.tableView.contentInset = UIEdgeInsets(top: headerView.bounds.height, left: 0, bottom: 0, right: 0)
$0.tableView.contentOffset = CGPoint(x: 0, y: -headerView.bounds.height)
}
}
No messy scroll inside scroll inside table view, no mangling with delegates, no duplicated scrolls, perfectly natural behavior. If you can't see the header, it is probably because of the tableView background color. You have to set it to clear, for the header to be visible from under the tableView.
I think there are two options.
Since you know the size of the scroll view and the main view, you are unable to tell whether the scroll view hit the bottom or not.
if (scrollView.contentOffset.y >= (scrollView.contentSize.height - scrollView.frame.size.height)) {
// reach bottom
}
So when it hit; you basically set
[contentScrollView setScrollEnabled:NO];
and other way around for your tableView.
The other thing, which is more precise I think, is to add Gesture to your views.
UITapGestureRecognizer *tapRecognizer = [[UITapGestureRecognizer alloc]
initWithTarget:self action:#selector(respondToTapGesture:)];
// Specify that the gesture must be a single tap
tapRecognizer.numberOfTapsRequired = 1;
// Add the tap gesture recognizer to the view
[self.view addGestureRecognizer:tapRecognizer];
// Do any additional setup after loading the view, typically from a nib
So when you add Gesture, you can simply control the active view by changing setScrollEnabled in the respondToTapGesture.
I found an awesome library
MXParallaxHeader
In Storyboard just set UIScrollView class to MXScrollView then magic happens.
I used this class to handle my UIScrollView when I embed a UIPageViewController container view. even you can insert a parallax header view for more detail.
Also, this library provides Cocoapods and Carthage
I attached an image below which represent UIViewHierarchy.
MXScrollView Hierarchy
SWIFT 5
I had some trouble using Vineet's answer for when I could not guarantee the scrollView content offset (Y) due to various different screen sizes. To resolve this, I changed the first trigger event of when the tableView's scroll gets enabled.
func scrollViewDidScroll(_ scrollView: UIScrollView) {
if scrollView.bounds.contains(button.frame) {
tableView.isScrollEnabled = true
}
if scrollView == tableView {
self.tableView.isScrollEnabled = (tableView.contentOffset.y > 0)
}
}
The scrollView.bounds.contains will check if a given element's frame is FULLY within the scrollView's visible content. I set this to a button that I have below the tableView. You could set this to your tableVIew's frame instead if your only condition is that your tableView is fully visible.
I left the original implementation of when to disable the tableView's scroll and it works very well.
I tried the solution marked as the correct answer, but it was not working properly. The user need to click two times on the table view for scroll and after that I was not able to scroll the entire screen again. So I just applied the following code in viewDidLoad():
tableView.addGestureRecognizer(UISwipeGestureRecognizer(target: self, action: #selector(tableViewSwiped)))
scrollView.addGestureRecognizer(UISwipeGestureRecognizer(target: self, action: #selector(scrollViewSwiped)))
And the code below is the implementation of the actions:
func tableViewSwiped(){
scrollView.isScrollEnabled = false
tableView.isScrollEnabled = true
}
func scrollViewSwiped(){
scrollView.isScrollEnabled = true
tableView.isScrollEnabled = false
}
One easy trick, if you want to achieve it is replacing parent scrollview with normal container view.
Adding a pan gesture on container view, you can play with top constraint of first view to assign negative values. You can keep a check of page View's origin if it achieves to top you can start assigning that value on content offset of the pageView's child view. Until user achieves the table view in a state of top most view in container view, you can keep page tableView's scrolling disabled and allow scrolling manually by setting content offset.
So initially the page view height will be collapsed (or say out of screen) or less at bottom. Later on scrolling down it will expand to take more space.
Gesture will automatically stop responding if out of frames say on nav bar or other view outside container view.
Gestures are a key to user interactive transitions used in many apps. You can mimic scroll for a certain time with it.
In my case I'm using constraint for height like that:
self.heightTableViewConstraint.constant = self.tableView.contentSize.height
self.scrollView.contentInset.bottom = self.tableView.contentSize.height
Below code works great for me
As I wanted to show some header after some scroll and table view supposed to scroll
And in ViewDidLoad add
override func viewDidLoad() {
super.viewDidLoad()
mainScrollView.delegate = self
}
Change 265 to whatever number you want to stop upper scroll
extension AccountViewController: UIScrollViewDelegate {
func scrollViewDidScroll(_ scrollView: UIScrollView) {
print(notebookTableView.contentOffset.y)
if notebookTableView.contentOffset.y < 265 {
if notebookTableView.contentOffset.y > 0 {
mainScrollView.setContentOffset(notebookTableView.contentOffset, animated: false)
} else {
mainScrollView.setContentOffset(CGPoint(x: 0.0, y: 0.0), animated: false)
}
} else {
mainScrollView.setContentOffset(CGPoint(x: 0.0, y: 265), animated: false)
}
}
}
CGFloat tableHeight = 0.0f;
YourArray =[response valueForKey:#"result"];
tableHeight = 0.0f;
for (int i = 0; i < [YourArray count]; i ++) {
tableHeight += [self tableView:self.aTableviewDoc heightForRowAtIndexPath:[NSIndexPath indexPathForRow:i inSection:0]];
}
self.aTableviewDoc.frame = CGRectMake(self.aTableviewDoc.frame.origin.x, self.aTableviewDoc.frame.origin.y, self.aTableviewDoc.frame.size.width, tableHeight);
Maybe brute-force, but working perfectly if cell heights are the same: by the way, I use auto layout.
for the tableView (or collectionView or whatever), set an arbitrary height in storyboard, and make an outlet to class. Wherever appropriate, (viewDidLoad() or...) set the tableView's height big enough so that tableView doesn't need to scroll. (need to know the number of rows in advance) Then only the outer scrollView will scroll nicely.

CollectionView takes a while to appear

I am using autolayout anchors to place my collectionView in my view. In my collectionView, I have a list of users. Since the number of cells is not definite, the height is changed based on the height of the content inside the collectionView. This is what have:
override func viewDidAppear(_ animated: Bool) {
let contentViewHeight = collectionView.getContentHeight() // Returns height of the content of the collectionView
collectionView.heightAnchor.constraint(equalToConstant: contentViewHeight).isActive = true
// I create a height constraint based on the contentHeight
self.collectionView.layoutIfNeeded()
}
This code works great, but the only side-effect is that my collectionView loads in a bit late when the view is shown. Everything else in the view is loaded, and the collectionView just pops up after a while. Is there any way I can add my constraint without causing this issue?
I tried moving my code to viewWillAppear and viewWillLayoutSubviews, but the anchor isn't even applied.

How to set items in collection view go bottom-to-top with swift

I'm making a collection view with fixed height and width and horizontal scroll direction.
At the start I will have 1 cell and I want it in the right side of the collection view instead of the left and when more cells are coming I want them to stack in the right side of the previous cell like 1 - 2 - 3.
I searched for an answer but all similar questions were for objective c.
Any thoughts how could I do this with swift?
Thanks in advance.
The problem is that if you try to set the contentOffset of your collection view in viewWillAppear, the collection view hasn't rendered its items yet. Therefore self.collectionView.contentSize is still {0,0}. The solution is to ask the collection view's layout for the content size.
Additionally, you'll want to make sure that you only set the contentOffset when the contentSize is taller than the bounds of your collection view.
func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
let contentSize: CGSize? = collectionView?.collectionViewLayout.collectionViewContentSize
if contentSize?.height > collectionView?.bounds.size.height {
let targetContentOffset = CGPoint(x: 0.0, y: (contentSize?.height)! - (collectionView?.bounds.size.height)!)
collectionView?.contentOffset = targetContentOffset
}
}

conflict scrolling scrollview and tableview

I have a scrollview that contain some element (uiimage, webview ,...)
in buttom of scrollview add tableview (comments list). Problem: although tableview is part of scrollview, but scrollview scroll separate and tableview scrolling separate!
I want at the end of scrollview and start tableview scrollview scrolling tableview and tableview scroll disabled.
I used it code:
Swift:
override func intrinsicContentSize() -> CGSize {
self.layoutIfNeeded()
return CGSizeMake(UIViewNoIntrinsicMetric, contentSize.height)
}
Objective C:
-(CGSize)intrinsicContentSize{
[self layoutIfNeeded];
return CGSizeMake(UIViewNoIntrinsicMetric, contentSize.height)}
but don't work.
thanks for help
That happens because it is the behavior of having a table view inside a scroll view. That should be happening.
Solution: Destroy the scrollView, and implement a tableView with a header view, wish that header view it will be the view with uiimage, webview etc... and the tableView it will be your comments. This is the best way of implementing what you want, that is if i understood right what you actually want.
Adding a header to a table view example:
self.tableView.tableHeaderView = topView // where top view is the view wish contains your uimage, buttons etc...
Avoid bounce of ScrollView when we scroll the tableview. I have added the below line of code.It worked for me.
self.scrollView.delegate = self
scrollView.contentSize = CGSize(width: self.view.frame.width, height: 500)
scrollView.showsVerticalScrollIndicator = true
scrollView.tag = 1
func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
if scrollView.tag != 1 {
self.scrollView.bounces = false
}
}
Thanks

Detect when label appears on screen in SWIFT

I have a scroll view with several elements (textview, label, image view...), I need to display an uiview when my label appears on the screen when I'm scrolling.
How can I do ?
Make sure your view controller is the scroll view delegate. Implement the scrollViewDidScroll method, and check whether the scroll view's frame, offset by the contentOffset, overlaps the label's frame.
func scrollViewDidScroll(scrollView: UIScrollView) {
let offset = self.scrollView.contentOffset
let onScreen = CGRectOffset(self.scrollView.frame, offset.x, offset.y)
if CGRectIntersectsRect(onScreen, self.label.frame) {
NSLog("Overlap")
}
}
If you want to detect when the label is fully on the screen, use CGRectContainsRect instead of CGRectIntersectsRect.

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