I need to update a constraint's value inside a UITableViewCell, which should trigger resizing of the cell. I need to know the correct frame before I can update the constraint's value, however having my code inside layoutSubviews() does not resize the cell. The subview which has the constraint attached to it grows, but cell stays the same initial height, cutting off the view.
My setup for the purpose of demonstration is very simple, I have a single UIView pinned to the edges of the cell's contentView, and a height constraint added to it. I expect the cell to resize when the height constraint of the view is changed.
override func layoutSubviews() {
super.layoutSubviews()
heightConstraint.constant = 500
}
Any ideas on why this is not working?
There are a couple quirks with changing cell height in layoutSubviews().
Typically, when a cell modifies its internal layout (constraints, etc), the cell must tell the table view to redraw itself.
In your case, the cell's layoutSubviews() is being called after the table view has determined the cell's height.
Couple ways around this, if you really do need to do that in layoutSubviews():
1 - call relaodData() in viewDidAppear()
2 - force the cell layout inside cellForRowAt:
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "MyCell", for: indexPath) as! MyCell
// set your cell properties here as usual - labels, images, etc...
cell.setNeedsLayout()
cell.layoutIfNeeded()
return cell
}
Related
I have a horizontal UIScrollView which is added as a subview inside custom UITableViewCell. For some cases, I want to change the scrollview content offset which I achieve by doing this code
cell.horizontalScrollView.setContentOffset(CGPoint(x: 300, y: cell.horizontalScrollView.contentOffset.y), animated: true)
inside the UITableView's cellForRowAtIndexPath function and tableview.reloadData() is called whenever I needed to scroll it programmatically.
The issue is, this does not work for the first time. ie,
When the tableview is loaded for the first time, the scrollviews inside the visible cells does not get scrolled according to the code. Its offset is just at (0,0). ---- (This is the issue!)
But after that, when I scrolled the tableView, then the new cells(reused cells) gets updated and scrollviews position gets changed. (which I needed from the start itself!)
So, I want to change the UIScrollView's initial offset(position) programmatically. How can I achieve that?
Atlast, I found the solution after sitting for a couple of days!
Had to implement layoutIfNeeded for the UITableViewCell inside the cellForRowAtIndexPath method before setting the contentOffset for the UIScrollView.
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "CustomCell", for: indexPath) as! CustomCell
cell.layoutIfNeeded()
cell.horizontalScrollView.setContentOffset(CGPoint(x: 300, y: cell.horizontalScrollView.contentOffset.y), animated: false)
return cell
}
The best way to implement this is to subclass your cell and then set the content offset in layoutSubviews method.
I have such problem, while trying to create a simple messenger.
Here what I came to:
class ChatBubleUIView that class is responsible for creating a bubleview with label in it. It works fine, calculating view height according to label height
Inside my cell I've created a content view. In the cell class, I'm adding new ChatBubleUIView instance as a subview to content View.
The problem is that, content doesn't scale up to the size of my ChatBubleInstance.
class ChatMessageTableViewCell: UITableViewCell, MessageCellConfiguration {
var message: Message?
override func awakeFromNib() {
super.awakeFromNib()
}
func configureCell() {
let chatBubleView = ChatBubleUIView(message: message!)
self.addSubview(chatBubleView)
}
}
In my tableView delegate
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "messageCell") as! ChatMessageTableViewCell
let data = currentUser.mesaageHistory[indexPath.row]
cell.message = data
cell.configureCell()
return cell
}
Also I have set estimated row height for my tableView
messageTableView.rowHeight = UITableViewAutomaticDimension
messageTableView.estimatedRowHeight = 44
What should I do to set to my tableView row height chatViewBubleUIView instance height.
Previously, I solved this problem using old-school approach, programmaticly determine chatViewBubleUIView instance height and then implement heightForRowAtIndexPath. But I'd like to do that using AutoLayoaut.
set your label's four constraint like top,bottom,leading,trailing and number of height of your label should be 0. Then it will automatically increased it's height as per content. If you are taking this label in any view then view's constrains should be same as label i have mentioned above!
Senario A:
If I set the label content in cellForRowAtIndexPath, the cell correctly get resized.
Senario B:
If I change the text content in custom action in cell, the cell sized does not get changed.(I do call setNeedsLayout + layoutIfNeeded)
How to fix this?
EDIT:
1) I have set,
myTableView.estimatedRowHeight = 71.0
myTableView.rowHeight = UITableViewAutomaticDimension
2) I have correctly added auto layout constraints.
I was running into this issue, and my problem was that I was constraining the content to self (the UITableViewCell) and not to self.contentView (the contentView OF the cell). Hope this helps someone else who has built their cells all in code!
In my case, the cell's custom size was enabled:
After you change the text of the cell, just reload that particular cell or simply call mainTableView.reloadData().
To reload that cell-
//indexPath is indexPath of cell you just changed label of
mainTableView.reloadRows(at: indexPath, with: .automatic)
In my case, in the same cell I had an imageView in the top left corner with a "center vertically in container" constraint, and a "top space container" constraint.
Obviously to satisfy this two constraint the cell must have an height equal to:
(height of the imageView / 2) + (length of the top space container constraint).
This height is not enough to fit the label text, so my label had only 1 line visible.
After I have deleted the imageView top constraint all went to the right place, in my case i wanted the image to be centered, if the image had to stay in the top left corner I had to take off the "center vertically in container" constraint.
I hope this can help someone.
First of all, I don't specifically know what was your action on UITableViewCell. So, I assume I do that in UITableViewCell selection.
The below answer only work on iOS 9 and above
But, for some reason, it failed to do it in iOS 8 until it scroll. So, I will update the answer for iOS 8.
I have seen you have used UITableView's estimatedRowHeight and rowHeight at your project. So,
Please check the following
Make sure UITableView's estimatedRowHeight and rowHeight include inside viewDidLoad()
Make sure your UILabel lines set to 0
Make sure there is no constraints about height for your UILabel and let the constraints be like that :
If there are other component also included, make sure only bottom and top space constraints included or top space to container margin and bottom space to container margin.
Every time that you want to update the cell, you have to reload tableView no matter what your current situation will be.
So, don't say anything yet before you try this sample project, #Rikh answer still work. May be you are going in wrong direction. Here's the solution. Please do as I said steps by steps and let me know if that didn't work out. You might need to share your sample project which is causing.
Sample Demo - DynamicCellDemo
UPDATE for iOS 8 : update the following code for iOS 8 users
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
if #available(iOS 9, *) {
// do nothing
} else {
tblDynamic.reloadData()
}
}
what you can do is set the AutoLayout constraints for the label in present in the cell from all the sides that is from Top, Bottom, Leading and Trailing. Then add the following UITableViewDelegate method to your class.
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return UITableViewAutomaticDimension
}
func tableView(_ tableView: UITableView, estimatedHeightForRowAt indexPath: IndexPath) -> CGFloat {
return 500
}
This will do the job. As now content in table view cell automatically adjusts the height of the cell.
Try this if it works:
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return UITableViewAutomaticDimension
}
func tableView(_ tableView: UITableView, estimatedHeightForRowAt indexPath: IndexPath) -> CGFloat {
return UITableViewAutomaticDimension
}
Add the following in your viewDidLoad()
-(void)viewDidLoad{
[super viewDidLoad];
tableView.rowHeight = UITableViewAutomaticDimension
tableView.estimatedRowHeight = 140
}
I have a subclass of UITableViewCell and a subclass of UITableViewController. I'm popualating the tableview with my custom cells.
I created a UITableViewCell in my storyboard, made its class my custom UITableViewCell Swift file, and gave it an identifier. Then I create cells in the controller with:
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("myIdentifier", forIndexPath: indexPath indexPath)
return cell
}
In my custom cell (on the storyboard) I have a UIImageView with the following constraints:
Image View Constraints
The constant for the top space constraint is 0, which I thought means the ImageView top would be flush with the cell top.
However, the images in my cell are pushed down a bit:
UITableView with custom cell
The white is just the table section header, that's working perfectly. However, you can see the orange gap that appears above the image (that orange is the background color of the cell), and I don't want that there.
I tried setting the image frame in the custom cell's awakeFromNib:
#IBOutlet weak var img: UIImageView!
override func awakeFromNib() {
img.frame = CGRectMake(0, 0, img.frame.width, img.frame.height)
}
But this had no effect, so I tried setting the frame in layoutSubviews:
override func layoutSubviews() {
img.frame = CGRectMake(0, 0, img.frame.width, img.frame.height)
}
This worked, but only after scrolling down and back up on the TableView. The first two cells have the orange gap, but if you scroll to the third one and back up, then the gap is gone.
Does anyone know why this is happening? How can I make the imageview be positioned at (0, 0) right away instead of only after scrolling down and back up?
When I try to reproduce your situation and drag the imageView to align to the top of the cell the Xcode suggested constraint is -8, and it works fine like that but if i set it to 0 I get the background color like your problem, try setting the top constraint to -8 or whatever Xcode is suggesting.
I'm not very familiar with AutoLayout so I can't clarify why Xcode wants to set it to -8
Try to set the height of tableViewCell through the following code:
func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
return UIScreen.mainScreen().bounds.width
}
I have a UITableView with custom UITableViewCells, each has a UIButton inside. I'm setting buttons' titles from an array, so the size of the buttons change according to the title. I need to return correct height based on the inner button's size in heightForRowAtIndexPath event.
Since I'm using auto layout, I've created an outlet for the button's height constraint and I'm updating it in the cell's layoutSubviews() event like this:
class CustomCell: UITableViewCell {
/* ... */
override func layoutSubviews() {
super.layoutSubviews()
self.myButton?.layoutIfNeeded()
self.heightConstraint?.constant = self.myButton!.titleLabel!.frame.size.height
}
}
Then I return the height based on the button height and top-bottom margins like so:
func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
var cell = tableView.dequeueReusableCellWithIdentifier("CustomCell") as! CustomCell
cell.myButton?.setTitle(self.data[indexPath.row], forState: UIControlState.Normal)
cell.bounds = CGRectMake(0, 0, CGRectGetWidth(tableView.bounds), CGRectGetHeight(cell.bounds))
cell.setNeedsLayout()
cell.layoutIfNeeded()
return cell.myButton!.systemLayoutSizeFittingSize(UILayoutFittingCompressedSize).height + (cell.topMarginConstraint!.constant * 2) /* top-bottom margins */ + 1 /* separator height */
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
var cell = tableView.dequeueReusableCellWithIdentifier("CustomCell") as! CustomCell
cell.myButton?.setTitle(self.data[indexPath.row], forState: UIControlState.Normal)
return cell
}
On the first launch, there seems to be no problem. However, after I begin scrolling, then the height of some rows seem to be mistaken. When I get back to the top, I see that previous cell heights get to be broken as well.
When I googled for similar problems, issue seems to be about reusable cells, though I was unable to find another way to calculate the height. What can be done to reuse cells correctly or getting the correct height, perhaps by another method?
More info and source code:
Constraints set by IB like this:
Here's the cells on the first launch:
After some scrolling:
Full code of the project can be found on Github.
According to this
Configure tableView as
func configureTableView() {
tableView.rowHeight = UITableViewAutomaticDimension
tableView.estimatedRowHeight = 160.0
}
Call it on your viewDidLoad method
Than configure your uibutton height constraint to be greater then or equal.
Override func tableView(tableView: UITableView, estimatedHeightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat where you can place your estimation height code
First off, it's better if you perform constraint updates in func updateConstraints() method of UIView. So instead of
override func layoutSubviews() {
super.layoutSubviews()
self.myButton?.layoutIfNeeded()
self.heightConstraint?.constant = self.myButton!.titleLabel!.frame.size.height
}
I would do
override func updateConstraints() {
self.myButton?.layoutIfNeeded()
self.heightConstraint?.constant = self.myButton!.titleLabel!.frame.size.height
super.updateConstraints()
}
Note that you should call the super implementation at the end, not at the start. Then you would call cell.setNeedsUpdateConstraints() to trigger a constraint update pass.
Also you should never directly manipulate the cell bounds the way you are doing in heightForRowAtIndePath: method, and even if you are completely sure that manipulating directly is what you want, you should manipulate cell.contentView's bounds, not the cell's bounds. If you are looking to adjust the cell height dynamically with respect to the dimensions of the content, you should use self sizing cells. If you need to support iOS 7, then this answer tells you how to achieve that behaviour with autolayout only (without touching the bounds etc).
To reiterate the answer, you should do:
func viewDidLoad() {
self.dummyCell = CustomCell.init()
// additional setup
}
func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
self.dummyCell.myButton?.setTitle(self.data[indexPath.row], forState: UIControlState.Normal)
self.dummyCell.layoutIfNeeded() // or self.dummyCell.setNeedsUpdateConstraints() if and only if the button text is changing in the cell
return self.dummyCell.systemLayoutSizeFittingSize(UILayoutFittingCompressedSize).height
}
Please know that the answer I linked to outlines a strategy to get the cell height via autolayout, so only writing the code changes I proposed won't be enough unless you set your constraints in a way that makes this solution work. Please refer to that answer for more information.
Hope it helps!
First of all, remove the height constraint of button and bind it to top and bottom with cell.
Then, in your cell' height, calculate height of the text based on the width and font of button. This will make the cell's height dynamic and you wont need height constraint anymore.
Refer the link below to get the height of text:
Adjust UILabel height to text
Hope it helps. If you need help further or understanding anything, let me know.. :)