Uitableview Height Does Not Change Dynamically in Swift iOS

Dynamically change UITableViewCell height - Swift 4

You code crashes because of this line

let cell = tableView.cellForRow(at: indexPath) as! AvailableRideCell

From Apple Documentation we know that this method is used for optimization. The whole idea is to get cells heights without wasting time to create the cells itself. So this method called before initializing any cell, and tableView.cellForRow(at: indexPath) returns nil. Because there are no any cells yet. But you're making force unwrapping with as! AvailableRideCell and your code crashed.

So at first, you need to understand, why you should not use any cells inside the cellForRow(at ) method.
After that, you need to change the logic so you could compute content height without calling a cell.

For example, in my projects, I've used this solution

String implementation

extension String {
    func height(for width: CGFloat, font: UIFont) -> CGFloat {
        let maxSize = CGSize(width: width, height: CGFloat.greatestFiniteMagnitude)
        let actualSize = self.boundingRect(with: maxSize,
                                           options: [.usesLineFragmentOrigin],
                                           attributes: [NSAttributedStringKey.font: font],
                                           context: nil)
        return actualSize.height
    }
}

UILabel implementation

extension String {
    func height(for width: CGFloat, font: UIFont) -> CGFloat {
        let labelFrame = CGRect(x: 0, y: 0, width: width, height: CGFloat.greatestFiniteMagnitude)
        let label = UILabel(frame: labelFrame)
        label.numberOfLines = 0
        label.lineBreakMode = .byWordWrapping
        label.font = font
        label.text = self
        label.sizeToFit()
        return label.frame.height
    }
}

With that, all you need to do is to compute your label and store its font.

var titles = ["dog", "cat", "cow"]

func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    // number of rows is equal to the count of elements in array
    return titles.count
}

func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
    let cellTitle = titles[indexPath.row]
    return cellTitle.height(forWidth: labelWidth, font: labelFont)
}

Dynamic rows height changing

If you'll need to update row height, all you need to do is to call this method when your content had been changed. indexPath is the index path of changed item.

tableView.reloadRows(at: [indexPath], with: .automatic)

Hope it helps you.

Label height in Cell won't change height dynamically

Initially the tableViewCell take the height according to the label's text i.e. Loading...

Once you get Questions response from the Firebase, to reflect the changes in the tableViewCell's content and its height, you need to reload the whole tableView, i.e.

tableView.reloadData()

Call the above code once you receive the API response and after updating the dataSource that you're using for the tableView.

Cannot Set Dynamic TableView Row Height

If you want to set the dynamic tableview row height, you must use autolayout.

Please set the constraint on the UI components in the cell as shown in the image below.

Sample Image

I used UILabel as sample code. For UILabel, be sure to set Lines to 0.

Here is the sample code

class ViewController: UIViewController {
    
    let stringArr = ["Uitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSaa", "Uitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSaaaa", "Uitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOS", "Uitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSaaaaaa", "Uitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSUitableview Height Does Not Change Dynamically in Swift iOSaaaaaa", "bbbb"]
    
    @IBOutlet weak var tableView: UITableView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        tableView.dataSource = self
        
        tableView.estimatedRowHeight = 100
        tableView.rowHeight = UITableView.automaticDimension
    }
}

extension ViewController: UITableViewDataSource {
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return stringArr.count
    }
    
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        guard let cell = tableView.dequeueReusableCell(withIdentifier: "TestCell", for: indexPath) as? TestCell else {
            return UITableViewCell()
        }
        
        cell.label.text = stringArr[indexPath.row]
        
        return cell
    }
}

You need to register the cell in the tableview.

tableView.register(UINib(nibName: “YourCellNibName”, bundle: nil), forCellReuseIdentifier: “YourCellReuseIdentifier”)