🐹 Easy life cycle observation
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If you're using MVVM
with FRP
, then chances are that you need to rely on UIViewController
or UIApplication
life cycle events to trigger signals. We can either do it by calling a method on the ViewModel
, like kickstarter-ios
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
self.viewModel.inputs.viewWillAppear()
}
or reactively using signal binding.
override func viewDidLoad() {
super.viewDidLoad()
rx.viewWillAppear.bind(to: viewModel.input.fetchData).disposed(by: disposeBag)
}
One way to make observations for the life cycle is to use sentMessage and methodInvoked which involve a lot of swizzlings 😱 We shouldn't use swizzlings, it is just asking for problem.
public extension Reactive where Base: UIViewController {
public var viewWillAppear: ControlEvent<()> {
let source = self.methodInvoked(#selector(Base.viewWillAppear)).mapVoid()
return ControlEvent(events: source)
}
}
Instead, we can just use simple composition, that you can plug and play everywhere you want. See demo
ViewControllerLifeCycle
for events related to UIViewController
AppLifeCycle
for events related to UIApplication
, equivalent to UIApplicationDelegate
This works by embed a child view controller so that it can forward appearance method
After adding a child to a container, the container automatically forwards appearance-related messages to the child
All you need to do is to declare ViewControllerLifeCycle
object and observe on it. Remember to keep this ViewControllerLifeCycle
so it is not released !!
let viewController = LoginViewController()
let lifeCycle = ViewControllerLifeCycle(viewController: viewController)
_ = lifeCycle.viewWillAppear.subscribe(onNext: {
print("viewWillAppear has been called")
})
For convenience, you can also use it directly by using rxLifeCycle
let viewController = LoginViewController()
_ = viewController.rxLifeCycle.viewDidAppear.subscribe(onNext: {
print("viewDidAppear has been called")
})
Supported observables
There are times we need to refresh data when user go back to the app again, which is the UIApplicationWillEnterForeground
event. All you need to do is to declare AppLifeCycle
and observe on it. Under the hood, it listens to UIApplication
notifications and publish the signals.
Remember to keep this AppLifeCycle
so it is not released !!
let lifeCycle = AppLifeCycle()
_ = lifeCycle.didBecomeActive.subscribe(onNext: {
print("didBecomeActive was called")
})
For convenience, you can also use it directly by using rxLifeCycle
on UIApplication
let lifeCycle = AppLifeCycle()
_ = UIApplication.shared.rxLifeCycle.willEnterForeground.subscribe(onNext: {
print("willEnterForeground was called")
})
Supported observables
RxLifeCycle is available through CocoaPods. To install it, simply add the following line to your Podfile:
pod 'RxLifeCycle'
RxLifeCycle is also available through Carthage. To install just write into your Cartfile:
github "onmyway133/RxLifeCycle"
RxLifeCycle can also be installed manually. Just download and drop Sources
folders in your project.
Khoa Pham, [email protected]
We would love you to contribute to RxLifeCycle, check the CONTRIBUTING file for more info.
RxLifeCycle is available under the MIT license. See the LICENSE file for more info.