UITableView cell height animation - xcode

Question

I do widget. I need to changed cell height with animation. When click "show more" go extra controls.
enter image description here
I wrote this code
tableView.beginUpdates()
showModes(alpha: 1, duration: 0.2, delay: 0.1)
tableView.endUpdates()
func showModes(alpha: CGFloat, duration: CGFloat, delay: CGFloat) {
if tableView.numberOfRows(inSection: 0) != 0 {
for i in 0...tableView.numberOfRows(inSection: 0)-1 {
let indexPath = IndexPath(row: i, section: 0)
if let cell = tableView.cellForRow(at: indexPath) as? WidgetCell {
UIView.animate(withDuration: TimeInterval(duration), delay: TimeInterval(delay) ,animations: {
if alpha == 0 {
cell.favoriteConstraint.constant = -45
} else {
cell.favoriteConstraint.constant = 10
}
cell.favoriteMode.alpha = alpha
self.tableView.layoutIfNeeded()
})
}
}
}
}
But it does not work smoothly. it dramatically twitches up and down. How do I get this to work smoothly, for example, in the weather widget by Apple?

Answer 1

I can't recognise what is a problem definetly because you posted only part of your code. But I can suggest several checks to do
Did you set self-sizing cells for UITableView? AtableView.rowHeight = UITableViewAutomaticDimension;
Did you added constraint (favoriteConstraint) to cell's contentView
Also when animating constraint changes you don't need to change it inside animation closure.
The standard code looks like
cell.favoriteConstraint.constant = newValue
UIView.animateWithDuration(0.3) {
cell.contentView.layoutIfNeeded()
}
Also you don't need to wrap your method call. This must be ok:
showModes(alpha: 1, duration: 0.2, delay: 0.1)
tableView.beginUpdates()
tableView.endUpdates()