Swift: Set UITextField.text from class (retrieved value from SQLite) - ios

Question

I am using Swift with SQLite.swift. I have the following UIViewController:
class LoginViewController: UIViewController {
#IBOutlet weak var emailField: UITextField!
func setEmailAddress(email:String){
emailField.text = email
}
override func viewDidLoad() {
MySQLite().updateLatestEmailAddressFromUserTable() // breaks here (email is in console, though...)
}
}
Then I am trying to update it's value (through the setEmailAddress function) from another class:
class MySQLite {
func updateLatestEmailAddressFromUserTable(){
let dbPath = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true).first as String
let db = Database("\(dbPath)/db.sqlite3")
let users = db["users"]
let id = Expression<Int>("id")
let email = Expression<String>("email")
let time = Expression<Int>("time")
for user in users.limit(1).order(time.desc) {
println(user[email]) // this works, correctly outputs in console: email#domain.com
LoginViewController().setEmailAddress(user[email]) // breaks here
}
}
}
above code gives me the following error
fatal error: unexpectedly found nil while unwrapping an Optional value
To explain a little further: I am retrieving the most recent entry in SQLite table to get the user's email address and update the text field in the login view controller. This allows for easier log in for returning users.
I have been struggling with this for over 2 hours now and trying various things. The main problem I believe is that when I try to simply return the email address as string from my second function and set the field directly from LoginViewController, it doesn't work (SQLite related code was not "executed" yet I believe).
possibly related thread (Obj-C):
set UITextField.text from another class

Answer 1

Here whats happening LoginViewController().setEmailAddress(user[email]) creates new instance of LoginViewController which is not same as your current LoginViewController.
Why don't you make protocol and define as delegate in MySQLite
And LoginViewController will have implementation of update method. Pass the delegate to MySqlite
In MySQLite when you get the value form database call the delegate update method.
Example
MySQLite
protocol loginDelegate
{
func update(NSString)
}
class MySQLite {
var delegate:loginDelegate?
func updateLatestEmailAddressFromUserTable(){
let dbPath = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true).first as String
let db = Database("\(dbPath)/db.sqlite3")
let users = db["users"]
let id = Expression<Int>("id")
let email = Expression<String>("email")
let time = Expression<Int>("time")
for user in users.limit(1).order(time.desc) {
println(user[email]) // this works, correctly outputs in console: email#domain.com
if((delegate) != nil)
{
delegate?.update("example#example.com")
}
}
}
}
class LoginViewController: UIViewController,loginDelegate {
#IBOutlet weak var emailField: UITextField!
func setEmailAddress(email:String){
emailField.text = email
}
override func viewDidLoad() {
var mySQLite: MySQLite=LoginClass();
mySQLite.delegate=self;
[mySQLite .updateLatestEmailAddressFromUserTable()];
}
func update(email: NSString) {
println(email);
emailField.text = email
}
}

Answer 2

Make sure that the view which has the emailField has been instantiated on the screen.
#IBOutlet weak var emailField: UITextField!
This is an optional, which will be nil until the storyboard or nib for it is loaded. I assume OnBoardingRegistrationFormController is an instance of your LoginViewController class?
I see you've accepted an answer, but in this case creating a protocol is likely overkill. If sqlite is your model, why not just have the function return a value, and then you can assign the value to the text field in the controller. ex.
class LoginViewController: UIViewController {
#IBOutlet weak var emailField: UITextField!
override func viewDidLoad() {
emailField.text = MySQLite().updateLatestEmailAddressFromUserTable()
}
}
class MySQLite {
func updateLatestEmailAddressFromUserTable() -> String{
let dbPath = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true).first as String
let db = Database("\(dbPath)/db.sqlite3")
let users = db["users"]
let id = Expression<Int>("id")
let email = Expression<String>("email")
let time = Expression<Int>("time")
for user in users.limit(1).order(time.desc) {
println(user[email]) // this works, correctly outputs in console: email#domain.com
return user[email]
}
}
}

Answer 3

The issue is that LoginViewController's view isn't loaded when you try to assign a text to the textField. i.e: emailField is nil and unwrapping nil values leads to a runtime crash (since the outlet has not been connected to it's storyboard/xib counterpart).