How to determine the size of collectionviewcell (xib) - ios

Question

Is there a way to measure the width and height of a cell defined in xib from within "sizeforitemat" function or any other function of viewcontroller, once data is dynamically generated? The default layout of the collection view makes it very shabby as depicted in output. Principally layout should have maximally two columns, and the rest of the empty spaces should be divided between cells within a row. So I want to loop over all the items, once it is filled with data to determine the maximum size of amongst cells to generate a layout according to its size. I'll highly appreciate the response.
viewcontroller.swift
import UIKit
class ViewController: UIViewController, UICollectionViewDelegate,
UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {
#IBOutlet weak var collectionView: UICollectionView!
let myCell: String = "CollectionViewCell"
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
self.collectionView.register(UINib(nibName:myCell, bundle: nil), forCellWithReuseIdentifier: myCell)
self.collectionView.delegate = self
self.collectionView.dataSource = self
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
150
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: myCell, for: indexPath) as! CollectionViewCell
cell.lbl1.text = "\(indexPath.row)"
cell.lbl2.text = "\(String(describing: cell.lbl2.text))\(indexPath.row)"
print ("***", indexPath.item, cell.bounds.size, collectionView.frame.size)
return cell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
// TODO: measure width and heigth of each cell to find number of columns
return collectionView.frame.size
}
}
collectionviewcell.swift
import UIKit
class CollectionViewCell: UICollectionViewCell {
#IBOutlet weak var lbl1: UILabel!
#IBOutlet weak var lbl2: UILabel!
override func awakeFromNib() {
super.awakeFromNib()
// Initialization code
}
}
viewcontroller's code
xib file's code
collection view cell
output

Answer 1

To find the "widest" cell, you can:
create an instance of your cell
loop through your data, setting the label values
get the width
track the maximum width
Something like this:
let theData: [String] = [
"Short",
"Longer",
"A bit longer",
"ABC",
"This is the longest one",
"Another medium",
"Last one"
]
let nib: UINib = UINib(nibName: "CollectionViewCell", bundle: nil)
let c = nib.instantiate(withOwner: nil, options: nil).first as! CollectionViewCell
var sz: CGSize = .zero
var maxW: CGFloat = 0
for i in 0..<theData.count {
c.lbl1.text = "\(i)"
c.lbl2.text = theData[i]
sz = c.systemLayoutSizeFitting(CGSize(width: .greatestFiniteMagnitude, height: 60.0),
withHorizontalFittingPriority: .defaultLow,
verticalFittingPriority: .required)
maxW = max(maxW, sz.width)
print("Row: \(i)", sz)
}
print("Max Width:", maxW)
Could give this in the debug output:
Row: 0 (50.0, 60.0)
Row: 1 (61.5, 60.0)
Row: 2 (95.5, 60.0)
Row: 3 (42.0, 60.0)
Row: 4 (179.5, 60.0)
Row: 5 (134.5, 60.0)
Row: 6 (73.5, 60.0)
Max Width: 179.5