As many people encountered, I tried to build tableView
. I found many similar questions but it seems answers are not helping. I would be very grateful if anyone could help me. The problem I encountered:
Fatal error: Unexpectedly found nil while implicitly unwrapping an Optional value
This is a description Xcode gives me
Here’s what I did:
(1) I connected Labels
in the storyboard to the class it related to, which should be right as it’s not hollow.
(2) I used tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
, and I tried to print cell
I got, all cells aren’t nil
and belongs to CollegeTableViewCell
, which is correct.
(3) I changed the identifier of tableViewCell to Cell
which matches, and I changed it’s class to CollegeTableViewCell
too.
My program crashed directly when it executes following code. I only works when I make labels optional. So the problem is what did I do wrong so that labels in cell are always nil?
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath) as! CollegeTableViewCell
let college = colleges[indexPath.row]
cell.collegeName.text = college.name // <-CRASH
cell.collegeGeo.text = college.city + ", " + college.state
return cell
}
Following is my CollegeTableViewCell
class:
class CollegeTableViewCell: UITableViewCell {
@IBOutlet weak var collegeName: UILabel!
@IBOutlet weak var collegeGeo: UILabel!
override func awakeFromNib() {
super.awakeFromNib()
// Initialization code
}
}
EDIT: more codes related to this problem.
class CollegeChooseViewController: UIViewController {
@IBOutlet weak var searchBar: UISearchBar!
@IBOutlet weak var tableView: UITableView!
var colleges = [CollegeInfo]()
let searchController = UISearchController(searchResultsController: nil)
let collegeApiUrl = "https://api.collegeai.com/v1/api/autocomplete/colleges?api_key=b47484dd6e228ea2cc5e1bf6ca&query="
override func viewDidLoad() {
super.viewDidLoad()
tableView.delegate = self
tableView.dataSource = self
tableView.register(CollegeTableViewCell.self, forCellReuseIdentifier: "Cell")
getColleges(contentInSearch: "MIT")
}
func getColleges(contentInSearch: String) {
guard let url = URL(string: (collegeApiUrl + contentInSearch)) else { return }
URLSession.shared.fetchData(for: url) {(result: Result<Initial, Error>) in
switch result {
case .success(let initial):
self.colleges = initial.collegeList
DispatchQueue.main.async {
self.tableView.reloadData()
}
case .failure(let error):
print("failed fetching college list from API: (error)")
}
}
}
}
extension URLSession {
func fetchData<T: Decodable>(for url: URL, completion: @escaping (Result<T, Error>) -> Void) {
self.dataTask(with: url) { (data, response, error) in
if let error = error {
completion(.failure(error))
}
if let data = data {
do {
let object = try JSONDecoder().decode(T.self, from: data)
completion(.success(object))
} catch let decoderError {
completion(.failure(decoderError))
}
}
}.resume()
}
}
extension CollegeChooseViewController: UITableViewDataSource, UITableViewDelegate {
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath) as! CollegeTableViewCell
let college = colleges[indexPath.row]
cell.collegeName.text = college.name // <-CRASH
cell.collegeGeo.text = college.city + ", " + college.state
return cell
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
print(colleges.count)
return colleges.count
}
}
class CollegeTableViewCell: UITableViewCell {
@IBOutlet weak var collegeName: UILabel!
@IBOutlet weak var collegeGeo: UILabel!
override func awakeFromNib() {
super.awakeFromNib()
// Initialization code
}
override func setSelected(_ selected: Bool, animated: Bool) {
super.setSelected(true, animated: true)
}
}
2
Answers
you’re using the wrong
bundle
name fordequeueReusableCell
.instead of
cell
useCollegeTableViewCell
it should be :
This is a sample of your tableview programmatically way… If I don’t know where your data comes from, I used a simulation of your arrays… conform your controller to UITableViewDelegate and Datasource:
Now set tableView and constraints
After that set your tableView Delegate and DataSource:
This is how your cell look like:
this is the result:
EDIT based on new information full code and Json decoder:
The cell:
The result: