PROVA

codegraphics.swift

class Disposable {
	typealias ClosureType = () -> Void
	let closure: ClosureType
	
	init(_ closure: @escaping ClosureType)
	{
		self.closure = closure
	}
	
	deinit
	{
		closure()
	}
}

extension NSObjectProtocol where Self: NSObject {
	func observe<Value>(_ keyPath: KeyPath<Self, Value>, onChange: @escaping (Value) -> ()) -> Disposable
	{
		let observation = observe(keyPath, options: [.initial, .new]) { _, change in
			guard let newValue = change.newValue else { return }
			onChange(newValue)
		}
		return Disposable { observation.invalidate() }
	}
}

//	How to use

@objc dynamic var toObserve: String = ""

let disposable = observe(\.toObserve, onChange: { value in
	debugPrint(“changed: \(value)")
})
		
toObserve = “Set new value“