Changing a Views textLabel from a different View - ios

Question

I have a custom class called colorChangerViewClass that inherits from UIView:
class colorChangerViewClass: UIView {
#IBOutlet weak var controller: ViewController!
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
// I want to change a textLabel in the main ViewController based on the current finger position here!
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
// And here aswell!
}
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) { ... }
func setColor(color: UIColor) {
self.backgroundColor = color
}
}
Inside the touchesBegan and touchesMoved methods I want to change a textLabel in the main ViewController (a different one) based on the current finger position.
What is the best way to establish communication between the two classes colorChangerViewClass and ViewController?

Answer 1

In your case you are trying to communicate child to parent, there are several ways from which you can gain desired out put.
1.Delegation
2. Notification
3. Passing Parent instance object to child (similar as delegate)
I am demonstrating with delegate, you can use delegation as:-
1. Declare
Declare a protocol somewhere out side your ColorChangerViewClass
protocol ColorChangerViewClassDelegate:class {
func fingerDidMoved()
}
2. Create delegate var inside your ColorChangerViewClass
class ColorChangerViewClass: UIView {
//declare delegate var
weak var delegate:ColorChangerViewClassDelegate?
#IBOutlet weak var controller: ViewController!
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
// I want to change a textLabel in the main ViewController based on the current finger position here!
self.notify()
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
self.notify()
// And here aswell!
}
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
}
func setColor(color: UIColor) {
self.backgroundColor = color
}
func notify() {
if let delegate = self.delegate {
delegate.fingerDidMoved()
}
}
}
3. Set Delegate of your view to the controller
class SomeVC:UIViewController,ColorChangerViewClassDelegate {
var myLabel = UILabel()
override func viewDidLoad() {
super.viewDidLoad()
//your view
let theView = ColorChangerViewClass() // you might need auto layout or frame declared on your view to define view size
theView.delegate = self
}
//MARK:-deleate method of view
func fingerDidMoved() {
// set text from here
self.myLabel.text = "Your text"
}
}

Answer 2

You are too close to solve the problem, you need to set the reference of your ViewController to controller property of your colorChangerViewClass. Also no need to declare controller as outlet so change its declaration like below.
var controller: ViewController?
Now in touchesBegan and touchesMoved use this controller to access textLabel
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
self.controller?.textLabel.text = //set text
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
self.controller?.textLabel.text = //set text
}
Now in your ViewController class where you are creating object of colorChangerViewClass set the controller property of it.
#IOutlet var colorView: colorChangerViewClass!
//set controller property in viewDidLoad
colorView.controller = self
Note: class name always start with Uppercase letters so it would be better if you changed your class name to ColorChangerViewClass from colorChangerViewClass.