Combine + PassthroughSubject + send.swift

class Counter {
    let publisher = PassthroughSubject<Int, Never>()
    
    private(set) var value = 0 {
        didSet {
            publisher.send(value)
        }
    }
    
    func increment() {
        value += 1
    }
}

let counter = Counter()
let cancellable = counter.publisher
    .filter { $0 > 2}
    .sink { value in
        print(value)
    }

counter.increment()
counter.increment()
counter.increment()
counter.increment()