DispatchCenter

gistfile1.txt

protocol SomeProtocol1: AnyObject {
    func doSth1()
}
protocol SomeProtocol2: AnyObject {
    func doSth2()
}

class Subscriber1: SomeProtocol1 {
    init() {}
    func doSth1() {
        print("doSth1")
    }
}
class Subscriber2: SomeProtocol2 {
    func doSth2() {
        print("doSth2")
    }
}

// Add or remove all observers of type
class DispatchCenter {
    private typealias WeakArray<T> = [() -> T?]

    private var observers1: WeakArray<SomeProtocol1> = [] 
    private var observers2: WeakArray<SomeProtocol2> = []

    //MARK: - Notify
    
    func notifySomeProtocol1() {
        observers1.forEach { $0()?.doSth1() }
    }
    func notifySomeProtocol2() {
        observers2.forEach { $0()?.doSth2() }
    }
    
    //MARK: - Add observer

    func addObserver(_ observer: SomeProtocol1) {
        observers1.append({ [weak observer] in return observer })
    }
    func addObserver(_ observer: SomeProtocol2) {
        observers2.append({ [weak observer] in return observer })
    }
}

class DispatchTripManager {
    let dispatchCenter = DispatchCenter()
    
    func test() {
        print("test")
        let a = Subscriber1()
        let b = Subscriber2()
        dispatchCenter.addObserver(a)
        dispatchCenter.addObserver(b)
        dispatchCenter.notifySomeProtocol1()
        dispatchCenter.notifySomeProtocol2()
    }
}


// ------------ Editable 

// Add and remove any specific observer
class DispatchCenter2 {
    private typealias WeakObj<T> = () -> T?

    private var observers1: [ String: [ WeakObj<SomeProtocol1> ] ] = [:]
    
    //MARK: - Notify
    
    func notifySomeProtocol1() {
        observers1["\(SomeProtocol1.self)"]?.forEach{ $0()?.doSth1() }
    }
    
    //MARK: - Add observer

    func addObserver(_ observer: SomeProtocol1) {
        if let observers = observers1["\(SomeProtocol1.self)"],
           observers.contains(where: {
               $0() === observer
           }) {
            return
        }
        if let observers = observers1["\(SomeProtocol1.self)"],
            !observers.isEmpty {
            observers1["\(SomeProtocol1.self)"]?.append({ [weak observer] in return observer })
        } else {
            observers1["\(SomeProtocol1.self)"] = [ { [weak observer] in return observer } ]
        }
        printCount()
    }
    
    //MARK: - Remove observer

    func removeObserver(_ observer: SomeProtocol1) {
        observers1["\(SomeProtocol1.self)"]?.removeAll(where:  {
            $0() === observer
        })
        printCount()
    }
    func removeObserversOfSomeProtocol1() {
        observers1.removeValue(forKey: "\(SomeProtocol1.self)")
        printCount()
    }
    
    func printCount() {
        print("Has \(observers1["\(SomeProtocol1.self)"]?.count ?? 0)")
    }
}


class DispatchTripManager2 {
    var dispatchCenter = DispatchCenter2()
    
    func test() {
        testAddObserver()
        testRemoveObserver()
        testRemoveObserversOfSomeProtocol1()
        testaddObserverTwice()
    }
    
    func testAddObserver() {
        dispatchCenter = DispatchCenter2()
        print("-- testAddObserver --")

        let a = Subscriber1()
        dispatchCenter.addObserver(a)
        dispatchCenter.notifySomeProtocol1()
        
        print("-- finish --")
    }
    
    func testRemoveObserver() {
        dispatchCenter = DispatchCenter2()
        print("-- testRemoveObserver --")

        let a = Subscriber1()
        dispatchCenter.addObserver(a)
        dispatchCenter.removeObserver(a)
        dispatchCenter.notifySomeProtocol1()
        
        print("-- finish --")
    }
    
    func testRemoveObserversOfSomeProtocol1() {
        dispatchCenter = DispatchCenter2()
        print("-- testRemoveObservers of SomeProtocol1 --")

        let a = Subscriber1()
        dispatchCenter.addObserver(a)
        dispatchCenter.removeObserversOfSomeProtocol1()
        dispatchCenter.notifySomeProtocol1()
        
        print("-- finish --")
    }
    
    func testaddObserverTwice() {
        dispatchCenter = DispatchCenter2()
        print("-- test add the same observer twice--")

        let a = Subscriber1()
        dispatchCenter.addObserver(a)
        dispatchCenter.addObserver(a)
        dispatchCenter.notifySomeProtocol1()
        
        print("-- finish --")
    }
}