swift - 使用 RxSwift 链接操作

Question

我想链接以下操作

• 创建用户并验证
  • 创建匿名用户(user)
  • 验证用户 -> verifiedUser
  • 如果验证成功返回verifiedUser 否则返回user
• 使用 coredata getStuff 获取内容
  • 如果 stuff.count > 0 使用用户凭证上传内容 uploadStuff
• 最后报告所有操作的结果

我写的 createUserandVerify 如下。我想知道我应该如何以 react 方式编写 uploadStuff 。上传功能取决于用户凭据。因此它只能在 createUserandVerify 之后运行。我知道我可以只检查 uploadStuff 中的数组计数并返回空，但我想知道最佳实践。

func createUserandVerify() -> Single<User> {
    return Service.sharedInstance.generateAnonUser()
        .flatMap{ user in
            if Service.sharedInstance.isOldRegisteredUser {
                print("It is old user")
                // We need to verify the receipt
                return  Service.sharedInstance.verifyReceipt()
                    .flatMap { verifiedUser in
                        print("Returning Verified new user [Verification Success]")
                        return Single.just((verifiedUser))

                    }.catchError{ error ->Single<User> in
                        print("Returning firstly created user [Verification Failed]")
                        print("Error Type: \(error)")
                        return Single.just(user)

                }
            } else {
                //Normal anonymous old user
                print("Returning firstly created user [Anonymous]")
                return Single.just(user)
            }
    }
}

Answer 1

假设(因为我没有使用 Single 我将它们更改为 Observable ):

func createUserandVerify() -> Observable<User>
func getStuff() -> [Stuff]
func uploadStuff(_ user: User) -> Observable<String> 

createUserandVerify()应该用 onError 发布错误所以uploadStuff如果出现问题，将不会被调用。

可能的解决方案:

enum CustomError: Error {
    case instanceMissing
    case notEnoughStuff
}

createUserandVerify()
    .flatMap { [weak self] (user) -> Observable<String> in
        guard let strongSelf = self else { throw CustomError.instanceMissing }
        guard strongSelf.getStuff().count > 0 else { throw CustomError.notEnoughStuff }
        return strongSelf.uploadStuff(user)
    }
    .subscribe(
        onNext: { stringResult in
          // print result from 'uploadStuff'
          print(stringResult)
    },
        onError: { error in
          // will be reached if something goes
          // wrong in 'createUserandVerify' or 'uploadStuff'
          // or if one of your custom errors in 'flatMap' are thrown
          print(error)
    })
    .disposed(by: disposeBag)

你也可以制作getStuff通过返回 Observable 来响应或 Single并通过 flatMap 将其包含在链中.