RxSwift源码分析(18)——deallocated

除了deallocating，还有deallocated：

vc.rx.deallocated
.subscribe { (event) in
    print("页面释放了")                
}

它的源码相对就简单多了，创建了DeallocObservable类并通过objc_setAssociatedObject关联起来：

extension Reactive where Base: AnyObject {
    
    public var deallocated: Observable<Void> {
        return self.synchronized {
            if let deallocObservable = objc_getAssociatedObject(self.base, &deallocatedSubjectContext) as? DeallocObservable {
                return deallocObservable._subject
            }

            let deallocObservable = DeallocObservable()

            objc_setAssociatedObject(self.base, &deallocatedSubjectContext, deallocObservable, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
            return deallocObservable._subject
        }
    }
    ...
}

fileprivate final class DeallocObservable {
    let _subject = ReplaySubject<Void>.create(bufferSize:1)

    init() {
    }

    deinit {
        self._subject.on(.next(()))  //发送
        self._subject.on(.completed)  //完成
    }
}

当页面释放时，DeallocObservable也会释放，接着deinit，然后就会发送响应和完成。