Can't center views in tableHeaderView with auto layout and storyboards - ios

I can't center a view that has been placed as a subview of a UITableView's tableHeaderView in a storyboard using auto layout.
In a storyboard, I have a UITableView. I dragged a UIView (the red view) to the top, released, and it created a table header view automatically. I then dragged and dropped another UIView (the yellow view) on top of the table header view, resized, and applied some constraints to ensure it stays centered:
When I run the app on the simulator, here's what I get:
The yellow view is obviously not centered. However, the "Filter" button at the bottom is.
I know it's tricky to get the height right using auto layout and storyboards and table header views (and you can see that the height of the red view is definitely incorrect), but at this point, I'm just trying to solve for horizontally centering my yellow view.
Am I able to set this all up in my storyboard without having to configure my constraints in code?

Make sure that your UITableView has the leading, trailing, bottom, top constraints set up against its superview.

Check the table header view and all sub views have Autoresize Subviews enabled:
You can also force the table to re-render the header view by re-setting it to the same view:
[self.tableView setTableHeaderView:self.outletToHeaderView];
Update: to resize the table header view, give give it an appropriate frame in viewWillAppear:
CGRect newFrame = self.outletToHeaderView.frame;
newFrame.size.width = self.tableView.bounds.size.width;
newFrame.size.height = 44;
[self.outletToHeaderView setFrame:newFrame];
// Then reset it to force the table view to re-render/accommodate
[self.tableView setTableHeaderView:self.outletToHeaderView]

In your file TableViewHeader:
override func awakeFromNib() {
super.awakeFromNib()
// Initialization code
yourView.translatesAutoresizingMaskIntoConstraints = false
yourView.centerXAnchor.constraint(equalTo: centerXAnchor).isActive = true
}

You need to use prototype cell from table view, than dequeue it with reusable identifier and return it contentView. Only that's do the trick
var headerView: UIView!
override func viewDidLoad() {
super.viewDidLoad()
self.headerView = (self.tableView.dequeueReusableCellWithIdentifier("CustomHeaderCell") as! UITableViewCell).contentView
}
override func tableView(tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
return self.headerView
}
upd:
Oh sorry, my example is written in Swift. But it's easy to understand how to do the same in Obj-C

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.

Make UICollectionViewCell's height match its content (sum height of all sub views) with AutoLayout

I found the next answer to make UIView's height match its content https://stackoverflow.com/a/39527226/7767664
I tested it, it works fine (if UIView height size in storyboard bigger or smaller than its content then during runtime it autoresize itself to match the content).
But if I use UICollectionViewCell instead of UIView then nothing changes, height of cell is never changed, it always has the hardcoded height we have in storyboard properties:
What else can I do?
Also I have 2 sections in UIControllerView (2 columns).
Two cells in one row should have the same size even if their size content is different (something like this implemented in Android natively when using RecyclerView with GridLayoutManager, very easy)
Update
It works with UIView because I set its top constraint to Safe Are'a top
I can't do it with UICollectionViewCell
Update 2
It seems I have some progress with this answer https://stackoverflow.com/a/25896386/7767664
But instead of newFrame.size.width = CGFloat(ceilf(Float(size.width))) I need newFrame.size.height = CGFloat(ceilf(Float(size.height)))
and when we use this solution, don't add any constraints to cell's bottom otherwise it will not work
With this solution I can't really use any margins otherwise some part of becomes invisible at the bottom of cell
I guess it can be solved with this question https://stackoverflow.com/a/31279726/7767664
You can try with this function called inside you collectionView Extension or inside your native collectionViewController class:
func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize
{
//return something like the size. I write you an example how to use it.
// You can easily change the value according to your stuff contents height.
return CGSize(width: collectionView.frame.size.width/3, height: 100)
}
I solved my issue thanks to https://stackoverflow.com/a/25896386/7767664 and https://stackoverflow.com/a/31279726/7767664
I decided to put one UIView with all needed child views inside it to UICollecitonViewCell
I set UIView trailing, leading, top to ICollecitonViewCell but I didn't set bottom to cell view (you should use the latest child view inside UIView and connect their bottoms, not with the cell view)
Then I added reference of UIView to my custom cell class and I use its height for cell's height:
public class MyCustomItemCell: UICollectionViewCell {
// other child views references ...
#IBOutlet weak var wrapperView: UIView! // view which contains your other views
//forces the system to do one layout pass
var isHeightCalculated: Bool = false
override public func preferredLayoutAttributesFitting(_ layoutAttributes: UICollectionViewLayoutAttributes) -> UICollectionViewLayoutAttributes {
//Exhibit A - We need to cache our calculation to prevent a crash.
if !isHeightCalculated {
setNeedsLayout()
layoutIfNeeded()
var newFrame = layoutAttributes.frame
newFrame.size.height = wrapperView.frame.height // use height of our UIView
layoutAttributes.frame = newFrame
isHeightCalculated = true
}
return layoutAttributes
}
}

Changing frame and contentInset of UICollectionView in layoutSubviews() using IGListKit

I need to change the frame and top content inset (contentInset.top) of my collection view (which is a UICollectionView). The top inset and frame changes depend on the bounds of the superview and the content offset of the collection view, thus I put the inset-changing code in layoutSubviews().
override func layoutSubviews() {
super.layoutSubviews()
collectionView.collectionViewLayout.invalidateLayout()
collectionView.contentInset.top = new_inset_top
collectionView.frame = new_frame
}
However, the collection view does not account for the new insets and the log shows the following:
The behavior of the UICollectionViewFlowLayout is not defined because:
the item height must be less than the height of the UICollectionView
minus the section insets top and bottom values, minus the content
insets top and bottom values.
How can I fix this to let the collection view displays correctly?
I am using IGListKit
You do not need to do all these inside of layoutSubviews.
in viewDidLoad implement it like following
func viewDidLoad() {
super.viewDidLoad()
// let say you want 40px top inset
collectionView.contentInset = UIEdgeInsetsMake(40, 0, 0, 0)
}
Another thing is that, i don't get, why are you setting the frame in layoutSubviews. There is no need to set frame to change the contentInset.

Dynamic height TableView in a Scroll View

I am designing a page having a scroll view and above it a table view(scroll disabled). For doing this I have referred answers in this question - Make UITableView not scrollable and adjust height to accommodate all cells ,but wasn't successful.
Hierarchy of views along with provided constraints-
-Main View
-Scroll view
pinned to all sides of main view(0,0,0,0), constraint to margins
-Content View
pinned to scroll view(0,0,0,0),equal width to main view,equal height to main view(priority - 250)
-Table view inside content view
scroll disabled,having 50 point spaces from all sides,Height(>=),bottom spacing 50(relation >=).I have put greater than equal so as to increase height dynamically.
Now when I populate my table view I use the code as
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell
{
let cell = tableview.dequeueReusableCellWithIdentifier("cellreuse", forIndexPath: indexPath)
cell.textLabel?.text = name[indexPath.row]
tableview.frame.size = tableview.contentSize
return cell
}
So when I run my code, it increases the tableview frame but doesn't stretch the content size and it just becomes weird as my scroll view doesn't scroll to the end of the table view neither my table view obeys the auto layout constraints.
Just I needed to do this -
remove the line - tableView.frame.size = tableView.contentSize
Add a height constraint for table view.
Set priority to High
Create an outlet of the height constraint(Ctrl+Drag).
Wherever you need to reload data of your table, set the height constraint to tableview's content height.
tableHeightConstraint.constant = tableview.contentSize.height
Assign a table height. Let it be constant 0.
Just add below lines.
tableView.heightConstant.constant = CGFloat.greatestFiniteMagnitude
tableView.reloadData()
tableView.layoutIfNeeded()
tableView.heightConstant.constant = tableView.contentSize.height
With this, you can easily achieve dynamic table height. Working on iOS 13, Swift 5.
Had the same issue and resolved it by doing the following:
Create an outlet of the height constraint for the table view with a priority of 1000
#IBOutlet private weak var tableViewHeight: NSLayoutConstraint!
On viewDidLayoutSubview call layoutIfNeeded on the table view and then set the table view height constraint to the height of the content view
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
tableView.layoutIfNeeded()
tableViewHeight.constant = tableView.contentSize.height
}
Tested on iOS 14.1 and iOS 16.1

Disable vertical scrolling in UICollectionView programmatically

I have a UICollectionView in a UITableViewCell. The height of the table view cell is set to the height of the collection view so the collection view only scrolls horizontally.
Sometimes when scrolling in the table view the collection view will capture the vertical scrolls and bounce scroll vertically. I've set the height to 0 in -collectionViewContentSize in my custom layout.
How do I completely disable vertical scrolling in a collection view?
In your storyboard - click your UICollectionView and open Utilities. Under the Attributes Inspector, center button, look to 'Bounces'. Uncheck "Bounces Vertically".
To completely disable vertical scrolling in a UICollectionView programatically, add the following to your viewDidLoad() method
self.collectionView.isScrollEnabled = false
Example:
class YourCollectionView: UICollectionViewController {
override func viewDidLoad() {
super.viewDidLoad()
self.collectionView.isScrollEnabled = false
}
// Then your methods for creating cells and layout, etc
}

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