RxSwift 小记 Error Handling Operators(catchError,retry)

最新推荐文章于 2025-07-22 19:39:34 发布

转载最新推荐文章于 2025-07-22 19:39:34 发布 · 156 阅读

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CC 4.0 BY-SA版权

原文链接：https://juejin.im/post/5b14a43a5188257d492ad94c

文章标签：

#rxswift

本文介绍RxSwift中几种常见的错误处理方法，包括 catchErrorJustReturn、catchError 和 retry 系列操作符的使用方式及应用场景，通过具体示例展示了如何优雅地处理错误。

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（*useful）标记：目前觉得有用的函数 //FIXME 标记：待补充 ##帮助捕获错误，并可以发送消息，平滑的处理error

####catchErrorJustReturn

example("catchErrorJustReturn") {
    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)
}
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打印： --- catchErrorJustReturn example --- next(?) next(?) next(?) next(?) next(?) //捕获的error completed

####catchError: 捕获错误，并return一个Observable sequence

example("catchError") {
    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)
    sequenceThatFails.onNext("errored")  
    recoverySequence.onNext("?")
}
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打印： next(?) next(?) next(?) next(?) Error: test //切换到了recoverySequence next(?)

####retry
#####重复订阅onError的sequence，indefinitely（可无限订阅

example("retry") {
    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)
}
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打印： --- retry example --- ? ? ? Error encountered ? //retry从这里开始，demo只进行了一个次error ? ? ? ? ?

####retry(_:) 跟上面的一样，加入了参数（控制retry的次数）

example("retry maxAttemptCount") {
    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)
}
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打印： --- retry maxAttemptCount example --- ? ? ? Error encountered ? ? ? Error encountered ? ? ? Error encountered Unhandled error happened: test subscription called from:

转载于:https://juejin.im/post/5b14a43a5188257d492ad94c