Why the cell height is not changing on tapping the button once. It is working only when I tap the button twice - tableview

Question

Click Here To see the UI of my app
Here In the image you can see the ui.
--> There is a tableView & a button on the main view.
--> I have taken a custom tableViewCell class
In the cell I have taken a UIView
Constraints Added To That View are:
centre horizontally, height, width, top & bottom constraint
I have added a outlet of the height constraint to the TVCell class
--> I have taken a button and added a event handler to it
--> Button Event handler:
In button event handler I am just changing the height of the view in the first cell and reloading the cell.
Now the problem is that height of the cell is changing when I tap on the button. But its happening only when I tap one the button twice. So I want to know why is it happening. Here I am adding my code below.
I have one solution for this problem which you can see after you see after the code of the ViewController & TableViewCell Class
VIEW CONTROLLER CLASS
import UIKit
class ViewController: UIViewController,UITableViewDataSource{
#IBOutlet weak var tableView: UITableView!
override func viewDidLoad() {
super.viewDidLoad()
tableView.dataSource = self
tableView.separatorColor = UIColor.black
}
func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 2
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
return cell
}
#IBAction func buttonAction(_ sender: Any) {
let indexPath = IndexPath(row: 0, section: 0)
let cell = tableView.cellForRow(at: indexPath) as! TableViewCell
if cell.viewHeightConstraint.constant == 75 {
cell.viewHeightConstraint.constant = 10
}
else{
cell.viewHeightConstraint.constant = 75
}
tableView.reloadRows(at: [indexPath] , with: UITableView.RowAnimation.automatic)
}
}
TABLEVIEWCELL CLASS
import UIKit
class TableViewCell: UITableViewCell {
#IBOutlet weak var viewHeightConstraint: NSLayoutConstraint!
override func awakeFromNib() {
super.awakeFromNib()
//Setting View Height To 75
viewHeightConstraint.constant = 75
}
override func setSelected(_ selected: Bool, animated: Bool) {
super.setSelected(selected, animated: animated)
}
}
You can get this source code from this link below
https://github.com/himansudev/tableViewIssue_15_4_20_1.git
Now I have a solution for this problem but I believe its not a proper solution. So what I have done is as shown below
1) I have modified the button event handler, see below is the modified code. Please refer to the above code to identify the changes that I have made to this event handler
#IBAction func buttonAction(_ sender: Any) {
let indexPath = IndexPath(row: 0, section: 0)
tableView.reloadRows(at: [indexPath] , with: UITableView.RowAnimation.automatic)
}
2) Secondly I have added this extra piece of code , see below
override func viewDidLayoutSubviews() {
print("viewDidLayoutSubviews")
let indexPath = IndexPath(row: 0, section: 0)
let cell = tableView.cellForRow(at: indexPath) as! TableViewCell
if cell.viewHeightConstraint.constant == 75 {
cell.viewHeightConstraint.constant = 10
}
else{
cell.viewHeightConstraint.constant = 75
}
}
Find the source code after changes below
https://github.com/himansudev/tableViewSolution_15_4_20_1.git
Now after doing these two changes it is working (but sometimes it doesn't work when I tap on the button rapidly many times) but the problem is the viewDidLayoutSubviews() is not getting called but when I comment it than the cell is not working as expected .
SO I want to know why is it behaving that way???

Answer 1

First of all you need to add also the UITableViewDelegate to your ViewController and a var like this:
class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
#IBOutlet weak var tableView: UITableView!
var cellHeight: CGFloat = 75
and the heightForRow function which will return the right Height:
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return cellHeight
}
Then on your button action:
#IBAction func buttonAction(_ sender: Any) {
if cellHeight == 75 {
cellHeight = 10
}
else{
cellHeight = 75
}
tableView.reloadData()
}
Also remove the constraint viewHeightConstraint because you do not need it.