RxSwift 系列(八)

前言

本篇文章我们将学习RxSwift中的错误处理，包括：

• catchErrorJustReturn
• catchError
• retry
• retry(_:)

catchErrorJustReturn

遇到error事件的时候，返回一个值，并且结束。更多详情

let disposeBag = DisposeBag()
    
let sequenceFail = PublishSubject<String>()
    sequenceFail.catchErrorJustReturn("😁").subscribe(onNext: {print($0)}).disposed(by: disposeBag)
    
sequenceFail.onNext("😝")
sequenceFail.onNext("😓")
sequenceFail.onError(TestError.test)

运行结果:

😝
😓
😁

catchError

捕获error进行处理，可以返回另一个sequence进行订阅。更多详情

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.onError(TestError.test)
    
recoverySequence.onNext("😊")

运行结果:

next(😬)
next(😨)
next(😡)
Error: test
next(😊)

retry

遇见error事件可以进行重试，比如网络请求失败，可以进行重新连接。更多详情

let disposeBag = DisposeBag()
var count = 1
    
let retrySequence = Observable<String>.create { (observer) -> Disposable in
    observer.onNext("🍎")
    observer.onNext("🍐")
        
    if count == 1 {
        observer.onError(TestError.test)
        print("Error encountered")
        count += 1
    }
        
    observer.onNext("🐶")
    observer.onNext("🐱")
        
    return Disposables.create()
}
    
retrySequence.retry().subscribe(onNext: {print($0)}).disposed(by: disposeBag)

运行结果:

🍎
🍐
Error encountered
🍎
🍐
🐶
🐱

retry(_:)
与retry相同，只是指定了重试次数。

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

运行结果:

🍎
🍐
🍊
Error encountered
🍎
🍐
🍊
Error encountered
🍎
🍐
🍊
Error encountered
Received unhandled error: Playground.xcplaygroundpage:41:__lldb_expr_18 -> test

致谢

如果发现有错误的地方，欢迎评论，感谢！