I am trying to adjust the size of each collection view cell according to the length of the label text contained within
func collectionView(collectionView: UICollectionView, layout collectionViewLayout:UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
var size = CGSize()
var cell = collectionView.dequeueReusableCellWithReuseIdentifier("lessonCell", forIndexPath: indexPath) as UICollectionViewCell
var label: UILabel = cell.viewWithTag(300) as UILabel
var labelSize = label.frame.size
size = labelSize
return size
}
When running the code, the app crashes with the error 'negative or zero sizes are not supported in the flow layout.' However, when I stepped through, I found that the crash occurs in initializing the cell variable, before the size is even determined. Why would initializing my cell variable throw this type of error?
I found my problem. I was using collectionView.dequeueReusableCellWithReuseIdentifier() when in reality this should only be used with the "cellForItemAtIndexPath" delegate method. What worked for me was the following code:
func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
var size = CGSize(width: 0, height: 0)
var label = UILabel()
label.text = category[indexPath.row]
label.sizeToFit()
var width = label.frame.width
size = CGSize(width: (width+20), height: 50)
return size
}
Related
For expanding label in UICollectionViewCell, I am using this library
My code is as below:
label.delegate = self
label.shouldCollapse = true
label.numberOfLines = 4
label.collapsed = true
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
let size: CGSize = "Modern Furniture reflects the design ilosophy of form following function prevalent in modernism. These designs represent the ideals of cutting excess, practicality and an absence of decoration.".size(withAttributes: [NSAttributedString.Key.font: UIFont.font_light(14)])
return CGSize(width: collectionView.frame.size.width , height: size.height + 390)
}
This thing works for UITableViewCell but it isn't working for UICollectionViewCell. In fact, the labels delegate methods are also not called.
I have a UICollectionViewCell which contains an image view and a label.
I am able to dynamically size the cell only when I have an image view.
I have added a label below the imageView with auto layout.
On viewDidLoad the image gets truncated or the text gets truncated. How can I dynamically size both the image view and label in the UICollectionViewCell.
Following is my code that works only with imageView
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: IndexPath) -> CGSize {
let imageSize = model.images[indexPath.row].size
return imageSize
}
I have an array of text and images from where I am displaying the content.
Any help will be appreciated. Thank you.
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: IndexPath) -> CGSize {
let imageSize = model.images[indexPath.row].size
//find the height of label on setting text.
//create a temp label
let tempLabel = UILabel()
tempLabel.numberOfLines = 0
tempLabel.text = "abcd" //set ur cells text here
let labelSize = tempLabel.intrinsicContentSize
return CGSize(width: imageSize.width + labelSize.width, height: imageSize.height + labelSize.height)
}
width of label = width of image view.
it is ok.
for height, you can use Intrinsic Content Size function to get size of label.
Here collectioncell is outlet of Collection view
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: IndexPath) -> CGSize {
let cellsize = CGSize(width: (collectioncell.bounds.size.width/2) - 12, height:(collectioncell.bounds.size.height/3) - 20)
return cellsize
}
Im currently attempting to calculate the height of a UICollectionViewCell dynamically but using a UILabel (the dynamic property) and the current height of the cell. The height is calculated by getting height for sizeThatFits of the label within the cell and adding that value to the original height of the cell. For some reason this always returns 0 in sizeForItemAt. I'm pretty sure the problem is the size is being calculated before the cell is created thus will always return 0. Is there anyway around this? (The UI for the cell is created within the class itself, not at celllForItemAt could that also be a problem?)
var descHeight: CGFloat = 0
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "desc", for: indexPath) as! ImageDescCell
descHeight = cell.descriptionLbl.sizeThatFits(cell.frame.size).height + cell.bounds.height
return cell
}
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
let w = collectionView.bounds.width
return CGSize(width: w, height: descHeight)
}
NSAttributedString can tell you how big an instance is, given a bound. So assuming you know how wide the label is and you know what the text is and what its attributes are you can get the size without ever creating a label:
let width = CGFloat(200)
let attributedString = NSAttributedString(string: "Test", attributes: [NSFontAttributeName : UIFont(name: "Helvetica", size: 18)!])
let boundingRect = attributedString.boundingRect(with: CGSize(width: width, height: CGFloat.greatestFiniteMagnitude), options: [.usesLineFragmentOrigin, .usesFontLeading], context: nil)
swift-3.0
func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize
{
let width = self.collectionView.frame.size.width
let Height = self.view.frame.size.height - 64 // 64 is a navigation bar height minus.
let cellSize:CGSize = CGSize(width: width, height: Height )
return cellSize
}
I have a collectionView with horizontal UICollectionViewFlowLayout.
I am trying to achieve:
If a device orientation is portrait, UIImageView width will be qual to view.width and let the height be calculated automatically (like it usually happens with Auto Layout). And the same for the landscape mode. Example - standard photo app on the Iphone.
Unfortunately i don't see how to achieve it with autoLayout. I set constraints on UIImageView for it to be equal in size to the cell. But looks like the sell itself cannot be pinned to the Parent View.
After reading similar questions looks like cells must be resized programmatically using
func collectionView(collectionView: UICollectionView,
layout collectionViewLayout: UICollectionViewLayout,
sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
return CGSize(width: width, height: height)
}
And here i am stuck because i know the width of the screen but don't know how to calculate the height dynamically.
About image height:
I have my image declared like this:
var pageImages = [UIImage]()
override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
let cell: ImageDetailViewCell = collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifier, forIndexPath: indexPath) as! ImageDetailViewCell
let curr = indexPath.row
let imgName = data[albumNumber][curr]["image"]
cell.DetailImageView.image = UIImage(named: imgName!)
return cell
}
If you use the proper UIImageView resize setting (say, aspect fit/fill), then you just need to set the cell's height to your collectionView's (you get a pointer to it as one of the ...sizeForItemAtIndexPath... method parameters) height. You also should call the - layoutIfNeeded method on your cell afterwards.
You can use sizeForItemAtIndexPath: to change the size of collection view cell.
func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
var numberOfCellInRow : Int = 3
var padding : Int = 5
var collectionCellWidth : CGFloat = (self.view.frame.size.width/CGFloat(numberOfCellInRow)) - CGFloat(padding)
return CGSize(width: collectionCellWidth , height: collectionCellWidth)
}
You can get the size of cell via :
((UICollectionViewFlowLayout) self.collectionViewName).itemSize.height)
You can get the image size via :
let sizeOfImage = image.size
let height = image.height
If you want to change the height then change it manually by return CGSize(width: collectionCellWidth , height: cellheight)
I've set the width of a cell(UICollectionViewCell) to be equal to the width of the UICollectionView and I'm trying to do exactly the same thing with the UILabel that is included inside that cell. I think the code below explains exactly what I'm trying to achieve. So i've read some question here in SO and also a couple of tutorials but I'm still not sure how I can achieve this.
In a couple of questions it was saying about using collectionViewLayout but I'm really struggling on how to use it within my code. Any ideas? Thank you!
func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
var cell = collectionView.dequeueReusableCellWithReuseIdentifier("myCell", forIndexPath: indexPath) as LocationViewCell
cell.locationLabel.text = "Hello there!"
// Set cell & label width to 100%
let collectionViewWidth = self.collectionView.bounds.size.width
cell.frame.size.width = collectionViewWidth // Works
cell.locationLabel.frame.size.width = collectionViewWidth // Does NOT
Update 1
So I added the following:
func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
// Set cell width to 100%
let collectionViewWidth = self.collectionView.bounds.size.width
return CGSize(width: collectionViewWidth, height: 35)
}
What happens is that when the view is loaded the UILabel's width is still small. If I go to another view and then return back then it's 100%. So I have to do something in the viewDidLoad() right? I'm already using self.collectionView.reloadData() but I guess that's only for data.
Update 2
func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
var cell = collectionView.dequeueReusableCellWithReuseIdentifier("locationCell", forIndexPath: indexPath) as LocationViewCell
cell.locationLabel.text = "Hello UILabel"
// Set cell width to 100%
let collectionViewWidth = self.collectionView.bounds.size.width
cell.frame.size.width = collectionViewWidth
cell.locationLabel.frame.size.width = collectionViewWidth
return cell
}
It doesn't work because by the time this method is called, the collection view already knows how big the cell should be because it has got it from the flow delegate method:
optional func collectionView(_ collectionView: UICollectionView,
layout collectionViewLayout: UICollectionViewLayout,
sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize
This is where you should be setting the size of your cells.