Unable to set a variable in UITableViewCell from parent ViewController - ios

Question

I have a UITableView and a custom TableViewCell class, I am setting a non-null value in viewDidLoad method, but while setting the value to UITableViewCell in cellForRow method , the value magically becomes nil. I am unable to access the set variable from my custom UITableViewCell
Here is the snippet of code. Print statement in ViewDidLoad prints the value while the one in cellForRowAtIndexPath returns nil
override func viewDidLoad() {
super.viewDidLoad()
Docco360Util.shared().getDoctorsWithResultBlock { (doctorObjects, error) in
if let err = error{
print(err)
}else{
self.doctors=doctorObjects
print(doctorObjects![1].professionalHeader)//output is printed here
self.doctorTableView.reloadData()
}
}
// Do any additional setup after loading the view.
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let identifierForUsers = "DoctorTableViewCell"
var cell = tableView.dequeueReusableCell(withIdentifier: identifierForUsers, for: indexPath) as! DoctorTableViewCell
if cell == nil{
cell=DoctorTableViewCell(style: .default, reuseIdentifier: identifierForUsers)
}
print(self.doctors[indexPath.row].professionalHeader)//output in nil here
cell.doctor=self.doctors[indexPath.row]
return cell
}

Answer 1

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "DoctorTableViewCell", for: indexPath) as! DoctorTableViewCell
print(self.doctors[indexPath.row].professionalHeader)
cell.doctor = self.doctors[indexPath.row]
return cell
}

Answer 2

First, you should ensure that the closure of Docco360Util.shared().getDoctorsWithResultBlock is executed in the main (UI) thread. If not, you should put it into a DispatchQueue.main.async block.
Then, you should verify that the result block is executed (e.g. the print statement prints something). Btw, why do you call print(doctorObjects![1].professionalHeader) with index 1 and not 0? In tableView(tableView:cellForRowAt:) you element with index 0 - maybe this doctor is nil?
You could start by setting a breakpoint to your property declaration, a watchpoint, or implement a property observer (willSet) and add a breakpoint her, to check if somebody is messing up with your variables.
If all this does not help, you might want to post more code, expecially all lines of code where you write your self.doctors array.

Answer 3

I could finally fix it. The problem was in declaration of variables. I was using Objective-C header file for declarations. While declaring I declared them as "weak" instead of "retain" and that was causing the problem.