xcode 8.3 error with generics - ios

Question

protocol PubSubEvent {
associatedtype EventResult
static func eventName() -> String
func event() -> EventResult
func send()
}
class BGEventBus: EventBus {
static let sharedInstance = BGEventBus()
init() {
super.init(queue: OperationQueue())
}
}
class BGEventBusEvent: PubSubEvent {
typealias EventResult = BGEventBusEvent
class func eventName() -> String {
return String(describing: self)
}
func send() {
BGEventBus.sharedInstance.send(event: self)
}
func event() -> BGEventBusEvent.EventResult {
return self
}
}
class BGDidLoginEvent: BGEventBusEvent {
typealias EventResult = BGDidLoginEvent
var password: String?
var facebookToken: String?
init(password: String? = nil, facebookToken: String? = nil) {
self.password = password
self.facebookToken = facebookToken
}
}
class EventBus {
var queue: OperationQueue
init(queue: OperationQueue) {
self.queue = queue
}
func send(event: AnyObject) {
}
func handleEvent<T: PubSubEvent>(target:EventBusObservable, handleBlock: ((T.EventResult) -> Void)!) where T.EventResult == T {
}
}
class EventBusObserver {
var objectProtocol: NSObjectProtocol?
func addObserver(forName name: NSNotification.Name?, object obj: Any?, queue: OperationQueue?, using block: #escaping (Notification) -> Swift.Void) {
self.objectProtocol = NotificationCenter.default.addObserver(forName: name, object: obj, queue: queue, using: block)
}
deinit {
if let obj = self.objectProtocol {
NotificationCenter.default.removeObserver(obj)
}
self.objectProtocol = nil
print("deinit observer!")
}
}
protocol EventBusObservable {
func handleBGEvent<T: PubSubEvent>(handleBlock: ((T.EventResult) -> Void)!) where T.EventResult == T
}
extension EventBusObservable {
func handleBGEvent<T>(handleBlock: ((T) -> Void)!) where T : PubSubEvent, T.EventResult == T {
BGEventBus.sharedInstance.handleEvent(target: self, handleBlock:handleBlock)
}
}
class sample: EventBusObservable {
func test() {
self.handleBGEvent { (event: BGDidLoginEvent) in
}
}
}
Hello guys I updated the Xcode to 8.3 and now I'm getting some errors like this:
Cannot convert value of type '(BGDidLoginEvent) -> ()' to expected argument type '((_) -> Void)!''
can anybody help me?
here the sample file https://drive.google.com/open?id=0B1zPtsTG7crPQncxYnEyWTBpSXM

Answer 1

I think you have to write the generic requirement exactly the same way every time. So, in EventBus:
class EventBus {
// ...
func handleEvent<T>(target:EventBusObservable, handleBlock: ((T) -> Void)!) where T : PubSubEvent, T.EventResult == T {
}
}
In EventBusObservable:
protocol EventBusObservable {
func handleBGEvent<T>(handleBlock: ((T) -> Void)!) where T : PubSubEvent, T.EventResult == T
}
In the EventBusObservable extension:
extension EventBusObservable {
func handleBGEvent<T>(handleBlock: ((T) -> Void)!) where T : PubSubEvent, T.EventResult == T {
BGEventBus.sharedInstance.handleEvent(target: self, handleBlock: handleBlock)
}
}
That compiles. Finally we are left with your class sample. This one wasn't so easy; I found I had to declare event as a BGEventBusEvent:
class sample: EventBusObservable {
func test() {
self.handleBGEvent {
(event:BGEventBusEvent) in
}
}
}