How to prevent the last table cell from overlapping with the keyboard - ios

Question

I have a chat app that displays the messages in a table view. When I invoke the keyboard, I want:
The table view to scroll to the bottom
I want there to be no overlap between any messages and the keyboard.
#objc private func keyboardWillShow(notification: NSNotification) {
if let userInfo = notification.userInfo {
let keyBoardFrame = (userInfo[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue
let keyboardViewEndFrame = view.convert(keyBoardFrame!, from: view.window)
let keyboardHeight = keyboardViewEndFrame.height
tableView.scrollToBottom() { indexPath in
let rectofCell = self.tableView.rectForRow(at: indexPath)
let lastCellFrame = self.tableView.convert(rectofCell, from: self.view.window)
if lastCellFrame.origin.y + lastCellFrame.size.height > keyboardViewEndFrame.origin.y {
let overlap = lastCellFrame.origin.y + lastCellFrame.size.height - keyboardViewEndFrame.origin.y
self.tableView.frame.origin.y = -overlap
}
}
}
}
extension UITableView {
func scrollToBottom(animated: Bool = true, completion: ((IndexPath) -> Void)? = nil) {
let sections = self.numberOfSections
let rows = self.numberOfRows(inSection: sections - 1)
if (rows > 0){
let indexPath = IndexPath(row: rows - 1, section: sections - 1)
self.scrollToRow(at: indexPath, at: .bottom, animated: true)
completion?(indexPath)
}
}
}
The value for rectOfCell shows (0.0, 5305.333518981934, 375.0, 67.33333587646484) and the converted value (0.0, 9920.000185648601, 375.0, 67.33333587646484) and the table view disappears out of the screen.
I only want to move the table view upward if the last message overlaps with the eventual position of the keyboard. For example, when the keyboard is invoked (either when the table view is already at the bottom or not at the bottom), the table view shouldn't move upward if the appearance of the keyboard doesn't cover the messages (i.e., there is only one message).

Answer 1

You don't need to manage tableView.frame for such a thing. You just need to make sure that when keyboard appears, tableView adds necessary contentInset value from bottom so that user can still see all the content inside tableView with the keyboard still on screen.
All you need is this -
// when keyboard appears
let insets = UIEdgeInsets(top: 0, left: 0, bottom: keyboardHeight, right: 0)
tableView.contentInset = insets
tableView.scrollIndicatorInsets = insets
// when keyboard disappears
let insets: UIEdgeInsets = .zero
tableView.contentInset = insets
tableView.scrollIndicatorInsets = insets