How to display a set number of rows in small Table View with self-sizing cells - swift

Question

I have a custom table view class, which is configured to set the table view height to display only 3 rows. This means if there are 20 rows, table view will be sized to display first 3 rows, and allowing user to scroll.
This code of mine works only if I set the static rowHeight
class CannedRepliesTableView: UITableView {
/// The max visible rows visible in the autocomplete table before the user has to scroll throught them
let maxVisibleRows = 3
open override var intrinsicContentSize: CGSize {
let rows = numberOfRows(inSection: 0) < maxVisibleRows ? numberOfRows(inSection: 0) : maxVisibleRows
return CGSize(width: super.intrinsicContentSize.width, height: (CGFloat(rows) * rowHeight))
}
}
If I set UITableViewAutomaticDimension to the rowHeight, table view is not properly resized. Is there a solution to this?

Answer 1

This would be one way to improve on what you currently have. I don't have experience accessing intrinsicContentSize for this calculations and didn't test this locally (other than syntax), but if previously it worked, this should as well.
Basically you're creating an array with maxVisibleRows number of indexPaths. If you have less, then fetchedIndexesCount prevents an indexOutOfBounds crash. Once you have the array, you iterate for each corresponding cell and fetching its size, finally summing it up.
class CannedRepliesTableView: UITableView {
var focussedSection = 0
let maxVisibleRows = 3
open override var intrinsicContentSize: CGSize {
return CGSize(width: super.intrinsicContentSize.width, height: calculateHeight())
}
private func calculateHeight() -> CGFloat {
guard let indexPaths = startIndexes(firstCount: 3) else {
// Your table view doesn't have any rows. Feel free to return a non optional and remove this check if confident there's always at least a row
return 0
}
return indexPaths.compactMap({ cellForRow(at: $0)?.intrinsicContentSize.height }).reduce(0, +)
}
private func startIndexes(firstCount x: Int) -> [IndexPath]? {
let rowsCount = numberOfRows(inSection: focussedSection)
let fetchedIndexesCount = min(x, rowsCount)
guard fetchedIndexesCount > 0 else {
return nil
}
var result = [IndexPath]()
for i in 0..<fetchedIndexesCount {
result.append(IndexPath(row: i, section: focussedSection))
}
return result
}
}