Gestion des erreurs HTTP POST dans Swift 2

Question

Gestion des erreurs HTTP POST dans Swift 2

je suis nouveau ici, et c'est ma première question... J'essaie d'écrire une application dans Swift 2 qui fait une requête HTTP POST, mais je n'arrive pas à comprendre comment utiliser la nouvelle gestion des erreurs de Swift 2. Quelqu'un peut-il me dire s'il vous plaît comment mettre en œuvre le "faire-try-catch " traitement des erreurs de Swift 2 à l'extrait de code ci-dessous? (Cet extrait de code utilise l'ancienne gestion des erreurs de swift 1.2)

func post(params : Dictionary<String, String>, url : String) {
    var request = NSMutableURLRequest(URL: NSURL(string: url)!)
    var session = NSURLSession.sharedSession()
    request.HTTPMethod = "POST"

    var err: NSError?
    request.HTTPBody = NSJSONSerialization.dataWithJSONObject(params, options: nil/*, error: &err*/)
    request.addValue("application/json", forHTTPHeaderField: "Content-Type")
    request.addValue("application/json", forHTTPHeaderField: "Accept")

    var task = session.dataTaskWithRequest(request, completionHandler: {data, response, error -> Void in
        print("Response: (response)")
        var strData = NSString(data: data!, encoding: NSUTF8StringEncoding)
        print("Body: (strData)")
        var err: NSError?
        var json = NSJSONSerialization.JSONObjectWithData(data!, options: .MutableLeaves/*, error: &err*/) as? NSDictionary

        // Did the JSONObjectWithData constructor return an error? If so, log the error to the console
        if(err != nil) {
            print(err!.localizedDescription)
            let jsonStr = NSString(data: data!, encoding: NSUTF8StringEncoding)
            print("Error could not parse JSON: '(jsonStr)'")
        }
        else {
            // The JSONObjectWithData constructor didn't return an error. But, we should still
            // check and make sure that json has a value using optional binding.
            if let parseJSON = json {
                // Okay, the parsedJSON is here, let's get the value for 'success' out of it
                var success = parseJSON["success"] as? Int
                print("Succes: (success)")
            }
            else {
                // Woa, okay the json object was nil, something went worng. Maybe the server isn't running?
                let jsonStr = NSString(data: data!, encoding: NSUTF8StringEncoding)
                print("Error could not parse JSON: (jsonStr)")
            }
        }
    })

    task!.resume()
}

16

error-handling http nsjsonserialization post swift2

demandé sur Rob 2015-06-24 18:13:40

2 réponses

score 36 · Answer 1

vous voulez probablement envelopper votre NSJSONSerialization appelle do/try/catch logique comme indiqué ci-dessous.

Dans Swift 3:

var request = URLRequest(url: URL(string: urlString)!)

let session = URLSession.shared
request.httpMethod = "POST"
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
request.addValue("application/json", forHTTPHeaderField: "Accept")

request.httpBody = try! JSONSerialization.data(withJSONObject: parameters)

// or if you think the conversion might actually fail (which is unlikely if you built `parameters` yourself)
//
// do {
//    request.httpBody = try JSONSerialization.data(withJSONObject: parameters)
// } catch {
//    print(error)
// }

let task = session.dataTask(with: request) { data, response, error in
    guard let data = data, error == nil else {
        print("error: \(error)")
        return
    }

    // this, on the other hand, can quite easily fail if there's a server error, so you definitely
    // want to wrap this in `do`-`try`-`catch`:

    do {
        if let json = try JSONSerialization.jsonObject(with: data) as? [String: Any] {
            let success = json["success"] as? Int                                  // Okay, the `json` is here, let's get the value for 'success' out of it
            print("Success: \(success)")
        } else {
            let jsonStr = String(data: data, encoding: .utf8)    // No error thrown, but not dictionary
            print("Error could not parse JSON: \(jsonStr)")
        }
    } catch let parseError {
        print(parseError)                                                          // Log the error thrown by `JSONObjectWithData`
        let jsonStr = String(data: data, encoding: .utf8)
        print("Error could not parse JSON: '\(jsonStr)'")
    }
}

task.resume()

Ou, dans Swift 2

let request = NSMutableURLRequest(URL: NSURL(string: urlString)!)

let session = NSURLSession.sharedSession()
request.HTTPMethod = "POST"
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
request.addValue("application/json", forHTTPHeaderField: "Accept")

request.HTTPBody = try! NSJSONSerialization.dataWithJSONObject(parameters, options: [])

// or if you think the conversion might actually fail (which is unlikely if you built `parameters` yourself)
//
// do {
//    request.HTTPBody = try NSJSONSerialization.dataWithJSONObject(params, options: [])
// } catch {
//    print(error)
// }

let task = session.dataTaskWithRequest(request) { data, response, error in
    guard let data = data where error == nil else {
        print("error: \(error)")
        return
    }

    // this, on the other hand, can quite easily fail if there's a server error, so you definitely
    // want to wrap this in `do`-`try`-`catch`:

    do {
        if let json = try NSJSONSerialization.JSONObjectWithData(data, options: []) as? NSDictionary {
            let success = json["success"] as? Int                                  // Okay, the `json` is here, let's get the value for 'success' out of it
            print("Success: \(success)")
        } else {
            let jsonStr = String(data: data, encoding: NSUTF8StringEncoding)    // No error thrown, but not NSDictionary
            print("Error could not parse JSON: \(jsonStr)")
        }
    } catch let parseError {
        print(parseError)                                                          // Log the error thrown by `JSONObjectWithData`
        let jsonStr = String(data: data, encoding: NSUTF8StringEncoding)
        print("Error could not parse JSON: '\(jsonStr)'")
    }
}

task.resume()

je suggère aussi d'être un peu plus prudent sur le déballage forcé de data, parce que vous voulez détecter/gérer les erreurs, pas de plantage. Par exemple, ci-dessus j'utilise un guard déclaration à déballer.

score 6 · Answer 2

En général, si une fonction throws vous devez écrire à l'intérieur d'un do catch bloquez ou marquez simplement la fonction externe scope (dans ce cas postthrows:

func post(params : Dictionary<String, String>, url : String) {
    let request = NSMutableURLRequest(URL: NSURL(string: url)!)
    let session = NSURLSession.sharedSession()
    request.HTTPMethod = "POST"

    do {
        request.HTTPBody = try NSJSONSerialization.dataWithJSONObject(params, options: .PrettyPrinted)
    } catch {
        //handle error. Probably return or mark function as throws
        print(error)
        return
    }
    request.addValue("application/json", forHTTPHeaderField: "Content-Type")
    request.addValue("application/json", forHTTPHeaderField: "Accept")

    let task = session.dataTaskWithRequest(request, completionHandler: {data, response, error -> Void in
        // handle error
        guard error == nil else { return }

        print("Response: \(response)")
        let strData = NSString(data: data!, encoding: NSUTF8StringEncoding)
        print("Body: \(strData)")

        let json: NSDictionary?
        do {
            json = try NSJSONSerialization.JSONObjectWithData(data!, options: .MutableLeaves) as? NSDictionary
        } catch let dataError {
            // Did the JSONObjectWithData constructor return an error? If so, log the error to the console
            print(dataError)
            let jsonStr = NSString(data: data!, encoding: NSUTF8StringEncoding)
            print("Error could not parse JSON: '\(jsonStr)'")
            // return or throw?
            return
        }


        // The JSONObjectWithData constructor didn't return an error. But, we should still
        // check and make sure that json has a value using optional binding.
        if let parseJSON = json {
            // Okay, the parsedJSON is here, let's get the value for 'success' out of it
            let success = parseJSON["success"] as? Int
            print("Succes: \(success)")
        }
        else {
            // Woa, okay the json object was nil, something went worng. Maybe the server isn't running?
            let jsonStr = NSString(data: data!, encoding: NSUTF8StringEncoding)
            print("Error could not parse JSON: \(jsonStr)")
        }

    })

    task!.resume()
}

si vous ne voulez pas gérer ces erreurs directement dans votre post fonction, vous pouvez simplement déclarer que throws que vous n'avez pas à utiliser do catch tout

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Gestion des erreurs HTTP POST dans Swift 2

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