Why I cannot set the labels with the data passed from one UIViewController to another (printing the data in console works) in Swift? - ios

Question

In my app I have an embedded UIViewController inside a container. In my story board I added a touch event to this viewcontroller and I called the segue: fullRequestSegue
Then in the code of that UIViewController I wrote:
class RequestDetails: UIViewController, ShowRequestDetailsFromMap {
var fullRequestDetails: FullRequestFromMap?
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if (segue.identifier == "fullRequestSegue"){
fullRequestDetails?.changeEventDescr(self.descr, username: "adam", number: "12", created_at: self.created_at, photo: self.photo)
fullRequestDetails = segue.destinationViewController as? FullRequestFromMap
fullRequestDetails!.showRequestDetails = self
}
}
}
Then in my class FullRequestFromMap I have:
protocol ShowRequestDetailsFromMap {
func changeEventDescr(text:String)
}
class FullRequestFromMap: UIViewController{
#IBOutlet weak var userNumber: UILabel!
var showRequestDetails:ShowRequestDetailsFromMap?
override func viewDidLoad() {
super.viewDidLoad()
}
func changeEventDescr(description: String, username: String, number: String, created_at: NSDate, photo: String) {
print(username)
print(description)
print(number)
print(created_at)
print(photo) //that works fine, I see all valid data in the console
userNumber.text = number //doesn't work, I see empty label instead of filled with passed data, the same problem is with other labels
}
What is the problem here?

Answer 1

The problem is when the method changeEventDescr is called the userNumber label is not initialized. You are trying to assign to a nil object.
Create a string variable in your FullRequestFromMap class and store text in it and in your viewDidLoad method you have to assign the text to userNumber label.
class FullRequestFromMap: UIViewController {
#IBOutlet weak var userNumber: UILabel!
var showRequestDetails:ShowRequestDetailsFromMap?
var userNumberLabelText:String = "Default Value"
override func viewDidLoad() {
super.viewDidLoad()
userNumber.text = userNumberLabelText
}
func changeEventDescr(description: String, username: String, number: String, created_at: NSDate, photo: String) {
print(username)
print(description)
print(number)
print(created_at)
print(photo)
userNumberLabelText = number // Here you set the class variable, not the label it self
}
}
class RequestDetails: UIViewController {
......
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if (segue.identifier == "fullRequestSegue") {
fullRequestDetails = segue.destinationViewController as? FullRequestFromMap
// Option 1: You can directly assign it
fullRequestDetails?.userNumberLabelText = "12"
// Option 2: You can call your method
fullRequestDetails?.changeEventDescr(self.descr, username: "adam", number: "12", created_at: self.created_at, photo: self.photo)
}
}
}