I have a viewcontroller which manages an uitableview with uicollectionviews in the uitableviewcells.
However, the uicollectionviews may contain varying numbers of items.
Therefore I need to adjust the height of the uicollectionviews.
But when I try to do this the heights of the other uicollectionviews are also changed.
The uicollectionview is bound by an IBOutlet, as well as the constraint for the height of the collection view.
I'm setting the height of the collectionview in
tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath):
cell.collectionView.reloadData();
cell.collectionViewHeight.constant = cell.collectionView.collectionViewLayout.collectionViewContentSize.height;
cell.collectionView.setNeedsLayout();
cell.collectionView.layoutIfNeeded();
First I'm reloading the data and then I'm setting the height constraint and finally I'm applying the new layout.
This seems to work at first - but I recognized that the other cells are also effected - probably because I'm dequeueing the reusable cell.
But how can I change my code, such that it works?
You should implement 'tableView:heightForRowAtIndexPath:'
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return 50.0
// Or customize the way you want using the indexPath
}
or for UICollectionView 'collectionView:sizeForItemAtIndexPath:'
func collectionView(_ collectionView: UICollectionView,
layout collectionViewLayout: UICollectionViewLayout,
sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: widthPerItem, height: heightPerItem)
}
Related
I have a collectionView that is populated from Firebase Realtime Database. It should work as whatsapp.
I have created a collectionView cell to show the messages in a label.
I have set the collectionView scroll direction to vertical.
I have set the cell height to 40, and here you have the method sizeForItemAt:
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width:collectionView.frame.size.width, height:40)
}
The items are shown, but not at full width and not one item per row.
Here you have a screenshot:
What do I need to change to get each item in a row?
Seems the method is not getting called here. You need to set the delegate of collectionView to the class. Add this to viewDidLoad.
collectionView.delegate = self
Suggested Approach: My suggested approach for your requirement is to use UITableView. All the cells extend the entire width of the UITableView. You just need to provide the height of the cell by this method.
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
40
}
I have a tableView, and within each UITableViewCell (call this parentCell), I have another tableView which has cells (call this childCell). I am using UITableViewAutomaticDimension to dynamically resize both of the cells height. I am successfully able to resize the height of the childCell this way, however, I am not able to apply UITableViewAutomaticDimension to the parentCell, since there when heightForRow is called, the childCell's height have yet to be estimated.
Is it possible to use UITableViewAutomaticDimension to estimate the parent cells height, which will be the height of all the childCell's height added together? Or am I going to have to do this manually?
//in ViewDidLoad
parentTableView.rowHeight = UITableViewAutomaticDimension
//in ParentCell's tableView's cell for row
cell.childTableView.rowHeight = UITableViewAutomaticDimension
func tableView(_ tableView: UITableView, estimatedHeightForRowAt indexPath: IndexPath) -> CGFloat {
return UITableViewAutomaticDimension
}
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return UITableViewAutomaticDimension
}
The only way to do this was to use sections instead of placing a tableview within a cell.
I am trying to create simple educational app about movies, and I need to create movie frames horizontal scroller.
I create collection view for that:
But if I build it for another target (iPhone 6s Plus for example), I have this:
How to solve this problem?
My scene controller code (Swift 3):
public func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 4
}
public func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath)
cell.backgroundColor = UIColor.black
// Configure the cell
return cell
}
override func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return UITableViewAutomaticDimension
}
I think that you can try to implement the method of UICollectionView delegate:
func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
return CGSizeMake(yourHeight, self.view.frame.size.width)
}
in this way, your collectionView-cell inside in tableView will appear as big as the screen.
First I want to say something about UITableViewAutomaticDimension you use, in case you not exactly understand how it works.
Your expectations probably are, that UITableViewAutomaticDimension will infer tableView to make a cell with size of entire tableView, but it doesn't work this way.
UITableViewAutomaticDimension is just infers tableView, that inner size of your cell will be used as a returned here; so if you add some constraints, views with constraints, or whatever inside your tV, its size will be used.
and second - your comment doesn't make sense at all for me, because your posted code isn't related to cell of collectionView and I can't comment anything related to size of its cells
EDITED:
to make all cells with width of your screen, return correct size from delegate method of collectionViewFlowLayout - sizeForItem
I have a table view controller with a navigation controller, and when there is no data for the table view, I want to display a single table cell with instructions on how to add new data. I can display the table cell, but I do not understand how I can get the height of the cell to span the visible height (table height - navigation item height). My goal is to have the label inside of my table cell be vertically centered in the device. I've tried using self.tableView.frame.height, but that gives me the scrollable height, which is larger than the visible area.
Edit: I failed to mention I'm doing this from tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat.
I have found a Good Enough™ answer to my own question:
override func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
tableView.isScrollEnabled = false
return tableView.frame.height - (self.navigationController?.navigationBar.frame.height)!
}
Here is an design issue in the app that uses AutoLayout, UICollectionView and UICollectionViewCell that has automatically resizable width & height depending on AutoLayout constraints and its content (some text).
It is a UITableView list like, with each cell that has it's own width & height calculated separately for each row dependant on its content. It is more like iOS Messages build in app (or WhatsUp).
It is obvious that app should make use of func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize.
Issue is that within that method, app cannot call func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell nor dequeueReusableCellWithReuseIdentifier(identifier: String, forIndexPath indexPath: NSIndexPath!) -> AnyObject to instantiate cell, populate it with specific content and calculate its width & height. Trying to do that will result in an indefinite recursion calls or some other type of app crash (at least in iOS 8.3).
The closest way to fix this situation seems to copy definition of the cell into view hierarchy to let Auto-layout resize "cell" automatically (like cell to have the same width as parent collection view), so app can configure cell with specific content and calculate its size. This should definitely not be the only way to fix it because of duplicated resources.
All of that is connected with setting UILabel.preferredMaxLayoutWidth to some value that should be Auto-Layout controllable (not hardcoded) that could depend on screen width & height or at least setup by Auto-layout constraint definition, so app can get multiline UILabel intrinsic size calculated.
I would not like to instantiate cells from XIB file since Storyboards should be today's industry standard and I would like to have as less intervention in code.
EDIT:
The basic code that cannot be run is listed bellow. So only instantiating variable cellProbe (not used) crashes the app. Without that call, app runs smoothly.
var onceToken: dispatch_once_t = 0
class ViewController: UICollectionViewController, UICollectionViewDelegateFlowLayout {
override func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 1
}
func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
dispatch_once(&onceToken) {
let cellProbe = collectionView.dequeueReusableCellWithReuseIdentifier("first", forIndexPath: NSIndexPath(forRow: 0, inSection: 0)) as! UICollectionViewCell
}
return CGSize(width: 200,height: 50)
}
override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCellWithReuseIdentifier("first", forIndexPath: NSIndexPath(forRow: 0, inSection: 0)) as! UICollectionViewCell
return cell
}
}
If you are using constraints, you don't need to set a size per cell. So you should remove your delegate method func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize
Instead you need to set a size in estimatedItemSize by setting this to a value other than CGSizeZero you are telling the layout that you don't know the exact size yet. The layout will then ask each cell for it's size and it should be calculated when it's required.
let layout = collectionView.collectionViewLayout as! UICollectionViewFlowLayout
layout.estimatedItemSize = someReasonableEstimatedSize()
Just like when dynamically size Table View Cell height using Auto Layout you don't need call
func tableView(_ tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell
in
optional func tableView(_ tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat
the proper way is create a local static cell for height calculation like a class method of the custom cell
+ (CGFloat)cellHeightForContent:(id)content tableView:(UITableView *)tableView {
static CustomCell *cell;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
cell = [tableView dequeueReusableCellWithIdentifier:[CustomCell cellIdentifier]];
});
Item *item = (Item *)content;
configureBasicCell(cell, item);
[cell setNeedsLayout];
[cell layoutIfNeeded];
CGSize size = [cell.contentView systemLayoutSizeFittingSize:UILayoutFittingCompressedSize];
return size.height + 1.0f; // Add 1.0f for the cell separator height
}
and I seriously doubt storyboard is some industry standard. xib is the best way to create custom cell like view including tableViewCell and CollectionViewCell
To calculate the CollectionView cell's size dynamically, just set the flow layout property to any arbitrary value:
let flowLayout = collectionView.collectionViewLayout as! UICollectionViewFlowLayout
flowLayout.estimatedItemSize = CGSize(width: 0, height: 0)