How to change variable value declared in a class from another class? - swift

Question

I have a 2 viewcontrollers, in vC1 a variable isShowListAsked : Bool = false is declared , on clicking map button it goes to vC2 . In vC2 there is a button named List.
I want that :
after clicking List button it go back to vC1 and vC1 variable value should changed to true. But it is still remains False.
Please help me .
Thanks in advance.
On clicking List button i am able to go back to vC1 but not able to set isShowListAsked = true . i tried get{} set {}.
In vC1 :
class vC1 : UIViewController
{
var isShowListAsked : Bool = false
var IsShowListAsked : Bool {
get {
return isShowListAsked
}
set{
isShowListAsked = newValue
}
}
}
Then after clicking In vC2 :
class vC2 : UIViewController
{
var vc = vC1()
#IBAction func mapListSegmentTapped(_ sender: Any) {
if mapListSegment.selectedSegmentIndex == 1
{
vc.IsShowListAsked = true
}
if mapListSegment.selectedSegmentIndex == 0
{
vc.IsShowListAsked = false
}
}
}
After going back i am checking variable value in viewWillappear()
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
print(" isshowListAsked = \(IsShowListAsked) ") // print false
}
Expected Result :
print(" isshowListAsked = \(IsShowListAsked) ") // print True
Actual Result :
print(" isshowListAsked = \(IsShowListAsked) ") // print false

Answer 1

Use Closures to solve your problem statement.
Create a closure in VC2 of type ((Bool)->())? and call it with the relevant true/false values in mapListSegmentTapped(_:) method, i.e.
class VC2: UIViewController {
var handler: ((Bool)->())?
#IBAction func mapListSegmentTapped(_ sender: Any) {
if mapListSegment.selectedSegmentIndex == 1 {
self.handler?(true)
} else if mapListSegment.selectedSegmentIndex == 0 {
self.handler?(false)
}
}
}
Now, set this closure when you're presenting the instance of VC2 from VC1 i.e.
class VC1 : UIViewController {
var isShowListAsked: Bool = false
func onTapMapButton(_ sender: UIButton) {
if let controller = self.storyboard?.instantiateViewController(withIdentifier: "VC2") as? VC2 {
controller.handler = {[weak self] (value) in
self?.isShowListAsked = value
print(self?.isShowListAsked)
}
self.present(controller, animated: true, completion: nil)
}
}
}