Swift spring animation is not working properly on a UITableViewCell - ios

Question

I have already read some issues and not properly uses about spring animations in Swift but I am a little bit confused about this case. I have a ViewController which has a UITableView. I would like to add some little spring bouncing animation to its cells. When a cell tapped it should be expanding and running the bouncing animation and it works perfectly for the first time. But after a cell is expanded and tapped again, the animation is ignored, but the code inside animations is perfectly running (e.g. a print command). Do you have any idea to achieve that goal to make the animation work twice or more? I think I theoretically missed something.
My ViewController:
class TestTableViewController: UIViewController {
#IBOutlet weak var tableView: UITableView!
var selectedIndex: IndexPath = IndexPath(row: 0, section: 0)
var isExpanded = [Bool]()
var currentExpandedIndexPath: IndexPath?
override func viewDidLoad() {
super.viewDidLoad()
isExpanded = Array(repeating: false, count: 15)
tableView.delegate = self
tableView.dataSource = self
}
}
extension TestTableViewController: UITableViewDelegate, UITableViewDataSource {
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 15
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "TestTableViewCell", for: indexPath) as! TestTableViewCell
cell.selectionStyle = .none
cell.animate(duration: 0.5, delay: 0.2, damping: 0.5, options: .curveEaseOut)
return cell
}
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
if isExpanded[indexPath.row] == true { return 300 }
return 150
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
// This is just for handling that to be only one cell that is expanded at one time
isExpanded[indexPath.row] = !isExpanded[indexPath.row]
if (currentExpandedIndexPath != nil) {
if (indexPath == currentExpandedIndexPath) {
currentExpandedIndexPath = nil
} else {
isExpanded[currentExpandedIndexPath!.row] = false
currentExpandedIndexPath = indexPath
}
} else {
currentExpandedIndexPath = indexPath
}
tableView.beginUpdates()
tableView.reloadRows(at: [indexPath], with: .automatic)
tableView.endUpdates()
}
}
And this is my TableViewCell class:
class TestTableViewCell: UITableViewCell {
func animate(duration: TimeInterval, delay: TimeInterval, damping: CGFloat, options: UIView.AnimationOptions = []) {
UIView.animate(withDuration: duration, delay: delay, usingSpringWithDamping: damping, initialSpringVelocity: 1, options: options, animations: {
self.contentView.layoutIfNeeded()
print("this command runs everytime")
})
}
}
These links are GIFs that show how it's working now. If I tap another cell after one expanded it has correct animation (first link). But if I tap the expanded one, it is not animated (second link).
Tapping one after one expanded
Tapping the same cell after it is expanded

Answer 1

There are two possibilities here:
1 - Following code possibly overrides your animation:
tableView.reloadRows(at: [indexPath], with: .automatic)
Try passing .none or some other flag.
2 - Following code must be called from main thread a.k.a DispatchQueue.main.
self.contentView.layoutIfNeeded()
There is also a 3rd possibility that is reloadRows does not necessarily call cellForRowAt where you are currently handling animations.