Execute a method when a variable value changes in Swift

Question

I need to execute a function when a variable value changes.

I have a singleton class containing a shared variable called labelChange. Values of this va

Answer 1

Apple provide these property declaration type :-

1. Computed Properties:-

In addition to stored properties, classes, structures, and enumerations can define computed properties, which do not actually store a value. Instead, they provide a getter and an optional setter to retrieve and set other properties and values indirectly.

var otherBool:Bool = false
public var enable:Bool {
    get{
        print("i can do editional work when setter set value  ")
        return self.enable
    }
    set(newValue){
        print("i can do editional work when setter set value  ")
        self.otherBool = newValue
    }
}

2. Read-Only Computed Properties:-

A computed property with a getter but no setter is known as a read-only computed property. A read-only computed property always returns a value, and can be accessed through dot syntax, but cannot be set to a different value.

var volume: Double {
    return volume
}

3. Property Observers:-

You have the option to define either or both of these observers on a property:

willSet is called just before the value is stored.
didSet is called immediately after the new value is stored.

public  var totalSteps: Int = 0 {
    willSet(newTotalSteps) {
        print("About to set totalSteps to \(newTotalSteps)")
    }
    didSet {
        if totalSteps > oldValue  {
            print("Added \(totalSteps - oldValue) steps")
        }
    }
}

NOTE:- For More Information go on professional link https://developer.apple.com/library/content/documentation/Swift/Conceptual/Swift_Programming_Language/Properties.html