Taming Delegates in RxSwift

Presented during Boost iOS knowledge sharing session

Transcript

1. Taming Delegates in RxSwift Created by Faiz Mokhtar
2. Hypothetical problem We want to chain our observable events but we're unable to do so since some of the methods uses delegate pattern. How can we make it more reactive? Created by Faiz Mokhtar
3. We can make use of DelegateProxy and DelegateProxyType! Created by Faiz Mokhtar
4. How to implement Created by Faiz Mokhtar
5. 1. Register and create proxy class extension CLLocationManager: HasDelegate {} class RxCLLocationManagerDelegateProxy: DelegateProxy<CLLocationManager, CLLocationManagerDelegate>, DelegateProxyType, CLLocationManagerDelegate { } Created by Faiz Mokhtar
6. 2. Initialize parent object weak public private(set) var locationManager: CLLocationManager? public init(locationManager: ParentObject) { self.locationManager = locationManager super.init(parentObject: locationManager, delegateProxy: RxCLLocationManagerDelegateProxy.self) } Created by Faiz Mokhtar
7. and register known implementation static func registerKnownImplementations() { register { RxCLLocationManagerDelegateProxy(locationManager: $0) } } Created by Faiz Mokhtar
8. 3. Implement the proxy and expose it to rx namespace extension Reactive where Base: CLLocationManager { var delegate: DelegateProxy<CLLocationManager, CLLocationManagerDelegate> { RxCLLocationManagerDelegateProxy.proxy(for: base) } } Created by Faiz Mokhtar
9. 4. Implement the observables for the delegate methods var authorizationStatus: Observable<CLAuthorizationStatus> { delegate.methodInvoked(#selector(CLLocationManagerDelegate .locationManager(_:didChangeAuthorization:))) .map { parameters in CLAuthorizationStatus(rawValue: parameters[1] as! Int32)! } .startWith(CLLocationManager.authorizationStatus()) } Created by Faiz Mokhtar
10. That's it! Now, the observables you've define should be available in rx namespace Created by Faiz Mokhtar
11. When to use it? Created by Faiz Mokhtar
12. Demo Created by Faiz Mokhtar
13. Further references → RxCocoa/DelegateProxy → RxCocoa/RxSearchBarDelegateProxy → RxCCocoa/RxScrollViewDelegateProxy → How Delegate Proxy works in RxSwift Created by Faiz Mokhtar
14. Thanks! Created by Faiz Mokhtar