https://github.com/krzyzanowskim/repetitivetask

https://github.com/krzyzanowskim/repetitivetask

Last synced: 7 months ago
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• Host: GitHub
• URL: https://github.com/krzyzanowskim/repetitivetask
• Owner: krzyzanowskim
• License: mit
• Created: 2016-01-06T23:43:09.000Z (almost 10 years ago)
• Default Branch: master
• Last Pushed: 2017-09-01T13:46:33.000Z (about 8 years ago)
• Last Synced: 2024-04-14T07:11:18.656Z (over 1 year ago)
• Language: Swift
• Homepage: http://blog.krzyzanowskim.com/2016/01/06/retry-in-the-wild/
• Size: 9.77 KB
• Stars: 40
• Watchers: 5
• Forks: 7
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
# RepetitiveTask

Implementation of Retry pattern in Swift for iOS/OSX.

### Definition of repetitive task

HTTP request with retry:

```swift

struct FailableTransientURLTask: RepetitiveTaskProtocol  {

    private var session: NSURLSession?

    private var url: NSURL

    private var archivedParameters: NSData

    /// Input parameters for the Task. This should be adjusted for the actual Task

    /// For this example required input is in parameters

    init(session: NSURLSession, url: NSURL, parameters: NSCoding) {

        self.session = session

        self.url = url

        self.archivedParameters = NSKeyedArchiver.archivedDataWithRootObject(parameters)

    }

    /// Run the request

    func run(completion: RepetitiveTaskProtocolCompletion) {

        guard let parameters = NSKeyedUnarchiver.unarchiveObjectWithData(self.archivedParameters), httpBody = try? NSJSONSerialization.dataWithJSONObject(parameters, options: []) else

        {

            fatalError("Missing parameters")

        }

        let request = NSMutableURLRequest(URL: self.url)

        request.HTTPBody = httpBody

        let sessionURLTask = session?.dataTaskWithRequest(request) { (data, response, error) in

            // success and error handling

            if let data = data {

                completion(RepetitiveTaskResult(success: data))

            } else if let error = error {

                // check if error is transient or final and throw right error

                if let delay = error.userInfo["ErrorRetryDelayKey"] as? NSNumber {

                    // request failed and can be retry later

                    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, Int64(delay.doubleValue * Double(NSEC_PER_SEC))), dispatch_get_main_queue(), {

                        completion(RepetitiveTaskResult(error: RepetitiveTaskError.RetryDelay(delay.doubleValue)))

                    })

                } else {

                    // request failed for other reason

                    completion(RepetitiveTaskResult(error: RepetitiveTaskError.Failed(error)))

                }

            } else {

                // no data received scenario

                completion(RepetitiveTaskResult(error: RepetitiveTaskError.NoData))

            }

        }

        sessionURLTask?.resume()

    }

}

```

###usage

```swift

let task = FailableTransientURLTask(session: NSURLSession.sharedSession(), url: NSURL(string: "http://blog.krzyzanowskim.com/rss")!, parameters: ["foo": "bar"])

//: Run task maximum 3 times hoping for success

task.run(retryCount: 3,

         failure: { (error) -> Void in

             print("failure \(error)")

         },

         success: { (data) -> Void in

             print("success \(data)")

         })

```