How can I constantly check if the value of a bool is true/false? SWIFT

Question

Hello my problem is simple I have to constantly check whether the value of a bool is true or false, what I have tried so far is to use the:

override func update(_ currentTime: TimeInterval) 

function in swift and it is way to fast and once it checks the values it will constantly repeat the action even though I only wish for it to perform the action only once, so basically what I'm saying is that all I want to do is to check whether the bool value is true or false once and then stop checking until it changes again. Please help, thank you.

Answer 1

Property Observers

You can use Property Observers in Swift to accomplish what you need... Here is what docs says about these:

Property observers observe and respond to changes in a property’s value. Property observers are called every time a property’s value is set, even if the new value is the same as the property’s current value.

There are willSet and didSet property observers:

• willSet is called just before the value is stored.

• didSet is called immediately after the new value is stored.

To solve your problem, you could do something like this:

 var myProperty:Int = 0 {

        willSet {
           print("About to set myProperty, newValue = \(newValue)")
        }

        didSet{
            print("myProperty is now \(myProperty). Previous value was \(oldValue)")
        }
    }

You can implement either one or both of property observers on your property.

Getters and Setters

As an alternative, You can use getters and setters on a stored property to solve your problem:

private var priv_property:Int = 0

var myProperty:Int{

    get {
        return priv_property
    }

    set {
        priv_property = newValue
    }
}

Computed properties do not actually store a value. Instead, they provide a getter and an optional setter to retrieve and set other properties and values indirectly.