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Notifications with generics
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enum Notifications { | |
public class Notification<T, Identifier: Equatable> { | |
private var allObservers: [WeakContainer] = [] | |
public var observers: [RegisteredObserver] { | |
observersRegisteredByOwners = observersRegisteredByOwners.filter({ $0.owner != nil }) // remove observers where owner is nil | |
let aliveObservers = allObservers.compactMap({ $0.value }) | |
if aliveObservers.count != allObservers.count { | |
allObservers = allObservers.filter({ $0.value != nil }) // remove dead observers | |
} | |
return aliveObservers | |
} | |
/// save returned token to have this observation alive. | |
public func register(identifier: Identifier? = nil, callback: @escaping (T) -> Void) -> Any { | |
let observation = RegisteredObserver(identifier: identifier, callback: callback) | |
allObservers.append(WeakContainer(value: observation)) | |
return observation | |
} | |
public func post(_ payload: T, identifier: Identifier? = nil) { | |
observers.filter({ $0.identifier == nil || $0.identifier == identifier }).forEach { $0.callback(payload) } | |
} | |
private var observersRegisteredByOwners: [RegisteredObserver] = [] | |
/// only while onwer is alive, callback will be triggered. No need to unregister | |
public func addObserver<Observer: AnyObject>(_ observer: Observer, identifier: Identifier? = nil, callback: @escaping (Observer, T) -> Void) { | |
let observation = RegisteredObserver(identifier: identifier, callback: { [weak observer] payload in | |
if let observer = observer { | |
callback(observer, payload) | |
} | |
}) | |
observation.owner = observer | |
allObservers.append(WeakContainer(value: observation)) | |
observersRegisteredByOwners.append(observation) // keep this observation alive until owner is deallocated | |
} | |
/// only while onwer is alive, callback will be triggered. No need to unregister | |
public func addObserver<Observer: NSObject>(_ observer: Observer, identifier: Identifier? = nil, selector: Selector) { | |
addObserver(observer, identifier: identifier, callback: { (observer, type) in | |
observer.perform(selector, with: type) | |
}) | |
} | |
/// remove all observations registered by owner | |
public func remove(owner: AnyObject) { | |
observersRegisteredByOwners = observersRegisteredByOwners.filter({ $0.owner !== owner }) | |
} | |
public class RegisteredObserver: CustomDebugStringConvertible { | |
public let identifier: Identifier? | |
public var callback: (T) -> Void | |
public weak var owner: AnyObject? | |
public init(identifier: Identifier?, callback: @escaping (T) -> Void) { | |
self.callback = callback | |
self.identifier = identifier | |
} | |
var debugDescription: String { | |
return String(describing: type(of: self)) + "_" + String(describing: T.self) + "_" + (identifier != nil ? String(describing:identifier!) : "") | |
} | |
} | |
private class WeakContainer { | |
weak var value: RegisteredObserver? | |
init(value: RegisteredObserver) { | |
self.value = value | |
} | |
} | |
} | |
} | |
extension Notifications.Notification where T == Void { | |
public func post(identifier: Identifier? = nil) { | |
post((), identifier: identifier) | |
} | |
// func register(identifier: Identifier? = nil, callback: @escaping () -> Void) -> Any { | |
// return register(identifier: identifier, callback: { (_) in | |
// callback() | |
// }) | |
// } | |
public func addObserver<Observer: AnyObject>(_ observer: Observer, identifier: Identifier? = nil, callback: @escaping (Observer) -> Void) { | |
addObserver(observer, identifier: identifier, callback: { (observer, _) in | |
callback(observer) | |
}) | |
} | |
} |
You probably want your internal
to be private
, non?
Yes, private is more appropriate. Thanks
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Examples of usages:
extension Notifications {
static let sessionClosed = Notification<Error?, String>() // payload, identity of payload
static let finishLoginRegisterFlow = Notification<Void, String>()
}
// trigger notification
Notifications.sessionClosed.post(error)
// observe
Notifications.sessionClosed.addObserver(self) { (self, error) in
}