I really don't know why my collectionViewCell disappear - swift

Question

I making a calendar so first I make a array like this [0,0,0,0,1,2,3,4,...,31] by thing.optimize(month: 5). in this array, the reason I make 0 in front of 1,2,3,...,31 is
when I make cell, I'm using an if statement so if cell.text == 0 then I set cell.isHidden = true.
When I select the one cell I reload both of collectionView(collectionView,nextMonthCollectionView) and make round red shape.
When I select another button, a problem occurs,
suddenly the cell disappears. I added a photo of this.
First, this is my code.
import UIKit
class ViewController: UIViewController {
#IBOutlet weak var nowMonthName: UILabel!
#IBOutlet weak var nextMonthName: UILabel!
#IBOutlet weak var collectionView: UICollectionView!
#IBOutlet weak var nextMonthCollectionView: UICollectionView!
var thing = realOptimaize()
var selectedIndex : IndexPath?
var items = [UIBarButtonItem]()
var forCollectionViewCount : Int?
var monthData : Array<Int>?
var nextMonthData : Array<Int>?
override func viewDidLoad() {
monthData = thing.optimaize(month: 5)
nextMonthData = thing.optimaize(month: 6)
self.title = String(CalenderBrain.init().curruntYear)
nowMonthName.text = String(CalenderBrain.init().curruntMonthName())
nextMonthName.text = String(CalenderBrain.init().nextMonthName())
self.collectionView.dataSource = self
self.collectionView.delegate = self
self.nextMonthCollectionView.dataSource = self
self.nextMonthCollectionView.delegate = self
self.collectionView.register(UINib(nibName: "CollectionViewCell", bundle: nil), forCellWithReuseIdentifier : "MyCell")
self.nextMonthCollectionView.register(UINib(nibName: "NextMonthCollectionViewCell", bundle: nil), forCellWithReuseIdentifier: "MyCell2")
//이해가 잘 안가는 부분!!!
if let layout = self.collectionView.collectionViewLayout as? UICollectionViewFlowLayout{
layout.minimumInteritemSpacing = -0.2
}
if let layout2 = self.nextMonthCollectionView.collectionViewLayout as? UICollectionViewFlowLayout{
layout2.minimumInteritemSpacing = -0.2
}
}
}
`extension ViewController : UICollectionViewDataSource, UICollectionViewDelegate,` UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
if collectionView == self.nextMonthCollectionView {
forCollectionViewCount = nextMonthData!.count
return forCollectionViewCount!
} else {
forCollectionViewCount = monthData!.count
return forCollectionViewCount!
}
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell { if collectionView == self.nextMonthCollectionView{
let forCollectionViewCell = nextMonthCollectionView.dequeueReusableCell(withReuseIdentifier: "MyCell2", for: indexPath) as! NextMonthCollectionViewCell
// forCollectionViewCell.button.tag = indexPath.item
if nextMonthData![indexPath.row] == 0 {
forCollectionViewCell.isHidden = true
} else {
forCollectionViewCell.Label.text = String(nextMonthData![indexPath.row])
}
return forCollectionViewCell
} else {
let forCollectionViewCell = collectionView.dequeueReusableCell(withReuseIdentifier: "MyCell", for: indexPath) as! CollectionViewCell
// forCollectionViewCell.button.tag = indexPath.item + 100
if monthData![indexPath.row] == 0 {
forCollectionViewCell.isHidden = true
} else {
forCollectionViewCell.Label.text = String(monthData![indexPath.row])
}
return forCollectionViewCell
}
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
if collectionView == nextMonthCollectionView {
return .init(width: 53.25 , height: 67)
} else{
return .init(width: 53.25 , height: 67)
}
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
if collectionView == self.nextMonthCollectionView {
let forCollectionViewCell = collectionView.cellForItem(at: indexPath) as! NextMonthCollectionViewCell
self.collectionView.reloadData()
collectionView.reloadData()
forCollectionViewCell.Label.textColor = .white
forCollectionViewCell.Label2.backgroundColor = .red
forCollectionViewCell.Label2.layer.cornerRadius = 0.5 * forCollectionViewCell.Label2.bounds.size.width
forCollectionViewCell.Label2.clipsToBounds = true
}else{
let forCollectionViewCell = collectionView.cellForItem(at: indexPath) as! CollectionViewCell
self.nextMonthCollectionView.reloadData()
collectionView.reloadData()
forCollectionViewCell.Label.textColor = .white
forCollectionViewCell.Label2.backgroundColor = .red
forCollectionViewCell.Label2.layer.cornerRadius = 0.5 * forCollectionViewCell.Label2.bounds.size.width
forCollectionViewCell.Label2.clipsToBounds = true
}
}
}
and this is my photo. this first photo is before I press any cell.
enter image description here
and this second photo is right after I press 13cell.
I really don't know why this happens.
I searched google looking for this information, but I didn't find an answer.
enter image description here
ps) when I don't use reloadData() function.. I did not get error.. but
I have to use reloadData.. because I have to clean my collectionView and then make a newly selected cell round red cell.

Answer 1

`if nextMonthData![indexPath.row] == 0 {
forCollectionViewCell.isHidden = true
} else {
forCollectionViewCell.isHidden =false
forCollectionViewCell.Label.text = String(nextMonthData![indexPath.row])
}
return forCollectionViewCell
}
`
setting else condition that will solve your problem.
The reason behind it is when collection view dequeuing cell may be that cell is already hidden that's why its disappearing.