issues with gridLayout in swift - ios

Question

So I have these delegate methods that help me layout my collectionView. I am trying to create somewhat of a grid layout where there are X numberOfSections and X numberOfItemsInSection. Based off of what I have now it lays out all of the rights next to each other and spaces them out a little too far as to where cells go to the next line. How do I go about fitting all the cells for a section on one line.
//Asks the delegate for the size of the header view in the specified section.
public func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
return .zero
}
//Asks the delegate for the size of the footer view in the specified section.
public func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForFooterInSection section: Int) -> CGSize {
return .zero
}
//Asks the delegate for the size of the specified item’s cell.
public func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: (collectionView.bounds.size.width - CGFloat(numberOfItemsInSection))/2.2, height: collectionView.bounds.size.height - 50)
}
//Asks the delegate for the margins to apply to content in the specified section.
//in short in controls the amount of space between the items above,left,right, and below
public func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
return UIEdgeInsetsMake(0.0, 0.0, 0.0, 0.0)
}
//Asks the delegate for the spacing between successive rows or columns of a section.
//controls the space in between rows and columns
public func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
return 1.0
}
//Asks the delegate for the spacing between successive items of a single row or column.
//controls the space between each cell
public func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
return 1.0
}
I feel like it has to do with the sizeForItemAt but I can't exactly figure out how to change it.
This is what it currently looks like.

Answer 1

You're right, it has to do with sizeForItemAt method, you should use the indexPath parameter so you can use its property section to define the size for each item in each section.
Just remember that there is a space between items so you need to take that into account when calculating the width and height, so you can adjust the spacing using minimumLineSpacingForSectionAt and minimumInteritemSpacingForSectionAt methods.
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
if indexPath.section == 0 {
return CGSize(width: 200, height: 100)
}
return CGSize(width: (collectionView.bounds.size.width - CGFloat(numberOfItemsInSection))/2.2, height: collectionView.bounds.size.height - 50)
}