[RxSwift] Single,Maybe,Completable 알아보기

Single 

success 또는 error 이벤트를 한 번만 방출될 수 있다. 

var disposeBag = DisposeBag()

enum TraitsError: Error {
    case single
    case maybe
    case completable
}

print("-------Single1-------") // 성공시 
Single<Result<String, TraitsError>>.just(.success("✅"))
    .subscribe(onSuccess: {
        print($0)
    }, onFailure: { _ in
        print("error")
    }, onDisposed: {
        print("disposed")
    })
    .disposed(by: disposeBag)

print("-------Single2-------") // 실패시
Observable<Result<String, TraitsError>>.just(.failure(.single))
    .asSingle()
    .subscribe(onSuccess: {
        print("success: \($0)")
    }, onFailure: {
        print("error: \($0.localizedDescription)")
    }, onDisposed: {
        print("disposed")
    })
    .disposed(by: disposeBag)

 

Single 를 이용한 decode 예제 

print("------single------")
struct SomeJSON: Decodable {
    let name: String
}

enum JSONError: Error {
    case decodingError
}

let json1 = """
    {"name":"hello"}
"""


func decode(json: String) -> Single<SomeJSON> {
    Single<SomeJSON>.create { observer in
        let disposable = Disposables.create()
        
        guard let data = json.data(using: .utf8),
              let json = try? JSONDecoder().decode(SomeJSON.self, from: data) else {
            
            observer(.failure(JSONError.decodingError))
            return disposable
        }
        
        observer(.success(json))
        return disposable
    }
}

decode(json: json1)
    .subscribe{
        switch $0 {
        case .success(let json):
            print(json.name)
        case .failure(let error):
            print(error)
        }
    }
    .disposed(by: disposeBag)
    
------single------
hello

 

 

Completable

comleted 이벤트 또는 error 이벤트를 방출될 수 있다. 

print("-------Completable-------")
Completable.create { completable in
    completable(.completed)
    return Disposables.create()
}
.subscribe(onCompleted: {
    print("completed")
}, onError: {
    print("error: \($0.localizedDescription)")
}, onDisposed: {
    print("disposed")
})
.disposed(by: disposeBag)


-------Completable-------
completed
disposed

 

Maybe

success, completed , error 모두 방출될 수 있다. 

print("-------Maybe1-------")
Maybe<Result<String, TraitsError>>.just(.success("✅"))
    .subscribe(onSuccess: {
        print("success: \($0)")
    }, onError: {
        print("error: \($0.localizedDescription)")
    }, onCompleted: {
        print("completed")
    }, onDisposed: {
        print("disposed")
    })
    .disposed(by: disposeBag)
 
 -------Maybe1-------
success: success("✅")
disposed

 

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Reference 

https://fastcampus.co.kr/dev_online_iosapp