EXC_BAD_ACCESS when inside heightForRowAt - ios

Question

I am trying to create expandable UITableViewCells using the following code:
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
let cell = tableView.cellForRow(at: indexPath) as! feedBaseCell
if cell.expandButton.isExpanded == true {
return 128
} else {
return 64
}
return 64
}
.isExpanded is a custom property of feedBaseCell. When I run this code, the line let cell = tableView.cellForRow(at: indexPath) as! feedBaseCell gets a EXC_BAD_ACCESS error. How can I check the .isExpanded property and return the height based on whether or not it is true or false? Why is my code not working?
EDIT: Code for both cellForRowAt and numberOfRowsInSection:
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 3
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "feedBaseCell") as! feedBaseCell
cell.backgroundColor = .clear
cell.selectionStyle = UITableViewCellSelectionStyle.none
cell.contentView.isUserInteractionEnabled = false
cell.expandButton.tag = indexPath.row
cell.expandButton.addTarget(self, action: #selector(self.expandTheCell(_:)), for: .touchUpInside)
cell.contentView.bringSubview(toFront: cell.expandButton)
return cell
}
Here is the expandTheCell method:
func expandTheCell(_ sender: UIButton) {
if sender.isExpanded == false {
UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 1, initialSpringVelocity: 1, options: .curveEaseOut, animations: {
sender.transform = sender.transform.rotated(by: .pi/2)
sender.isExpanded = true
}, completion: nil)
} else {
UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 1, initialSpringVelocity: 1, options: .curveEaseOut, animations: {
sender.transform = sender.transform.rotated(by: -.pi/2)
sender.isExpanded = false
}, completion: nil)
}
tableView.beginUpdates()
tableView.endUpdates()
}

Answer 1

Never call cellForRow(at:) from within heightForRowAt. It causes infinite recursion because the table view tries to get the cell's height when you ask for the cell.
If you really, really need to get a cell to calculate its height, directly call your view controller's dataSource method tableView(_:cellForRowAt:) method instead of the table view's cellForRow(at:) method.
But in this case you don't need the cell. You should be storing the expanded state of each row in your data source data, not in the cell itself. Look at that data, not the cell, to determine the height in your heightForRowAt method. And of course you will need this state information in your cellForRowAt data source method so you can set the cell's state there since cells get reused as you scroll the table view.