幫助從可觀察到的錯誤通知中恢復(fù)的操作

catchErrorJustReturn

通過返回一個可觀察到的序列，從一個錯誤事件中恢復(fù)，然后發(fā)出一個元素，然后終止。

let disposeBag = DisposeBag()

let sequenceThatFails = PublishSubject<String>()

sequenceThatFails
    .catchErrorJustReturn("??")
    .subscribe { print($0) }
    .disposed(by: disposeBag)

sequenceThatFails.onNext("??")
sequenceThatFails.onNext("??")
sequenceThatFails.onNext("??")
sequenceThatFails.onNext("??")
sequenceThatFails.onError(TestError.test)    
//  next(??)next(??)next(??)next(??)next(??)completed

catchError

通過切換到所提供的恢復(fù)序列來從錯誤事件中恢復(fù)

let disposeBag = DisposeBag()
    
    let sequenceThatFails = PublishSubject<String>()
    let recoverySequence = PublishSubject<String>()
    
    sequenceThatFails
        .catchError {
            print("Error:", $0)
            return recoverySequence
        }
        .subscribe { print($0) }
        .disposed(by: disposeBag)
    
    sequenceThatFails.onNext("??")
    sequenceThatFails.onNext("??")
    sequenceThatFails.onNext("??")
    sequenceThatFails.onNext("??")
    sequenceThatFails.onError(TestError.test)
    
    recoverySequence.onNext("??")
//next(??) next(??) next(??) next(??) Error: test next(??)

retry

通過重新訂閱的可觀察序列多次恢復(fù)錯誤事件，無限期

let disposeBag = DisposeBag()
var count = 1

let sequenceThatErrors = Observable<String>.create { observer in
    observer.onNext("??")
    observer.onNext("??")
    observer.onNext("??")
    
    if count == 1 {
        observer.onError(TestError.test)
        print("Error encountered")
        count += 1
    }
    
    observer.onNext("??")
    observer.onNext("??")
    observer.onNext("??")
    observer.onCompleted()
    
    return Disposables.create()
}

sequenceThatErrors
    .retry()
    .subscribe(onNext: { print($0) })
    .disposed(by: disposeBag)
//??????Error encountered????????????

retry(_:)

出錯重新訂閱支持次數(shù)

let disposeBag = DisposeBag()
var count = 1

let sequenceThatErrors = Observable<String>.create { observer in
    observer.onNext("??")
    observer.onNext("??")
    observer.onNext("??")
    
    if count < 5 {
        observer.onError(TestError.test)
        print("Error encountered")
        count += 1
    }
    
    observer.onNext("??")
    observer.onNext("??")
    observer.onNext("??")
    observer.onCompleted()
    
    return Disposables.create()
}

sequenceThatErrors
    .retry(3)
    .subscribe(onNext: { print($0) })
    .disposed(by: disposeBag)

Debugging 操作