帮助从可观察到的错误通知中恢复的操作

catchErrorJustReturn

通过返回一个可观察到的序列，从一个错误事件中恢复，然后发出一个元素，然后终止。

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

通过切换到所提供的恢复序列来从错误事件中恢复

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

通过重新订阅的可观察序列多次恢复错误事件，无限期

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(_:)

出错重新订阅支持次数

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