swifty json - What is this success method? (Swift Closure) -

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so copy pasted code ray wenderlich's swifty json tutorial , haven't been able understand of calls making.

i've scanned through swiftyjson library, looked @ nsurl description on developer site , checked out swift guide either can't find or bunch of miscellania back.

what these success calls mean?

    func getindexwithsuccess(success: ((indexdata: nsdata!) -> void)) {         loaddatafromurl(nsurl(string: url)!, completion:{(data, error) -> void in             if let urldata = data {                 /* here */                 success(indexdata: urldata)             }         })     }      func loaddatafromurl(url: nsurl, completion:(data: nsdata?, error: nserror?) -> void) {         var session = nsurlsession.sharedsession()          let loaddatatask = session.datataskwithurl(url, completionhandler: { (data: nsdata!, response: nsurlresponse!, error: nserror!) -> void in             if let responseerror = error {                 completion(data: nil, error: responseerror)             } else if let httpresponse = response as? nshttpurlresponse {                 if httpresponse.statuscode != 200 {                     var statuserror = nserror(domain:"com.raywenderlich",                         code:httpresponse.statuscode,                         userinfo:[nslocalizeddescriptionkey : "http status code has unexpected value."])                     completion(data: nil, error: statuserror)                 } else {                     completion(data: data, error: nil)                 }             }         })         loaddatatask.resume()     } }

notice says:

func getindexwithsuccess(success: ((indexdata: nsdata!) -> void)) {

that means success parameter. follows after colon closure.

success, therefore closure.

now, how should interpret closure?

https://developer.apple.com/library/ios/documentation/swift/conceptual/swift_programming_language/closures.html

note, above closure includes parentheses clarity.

you can leave shorten above removing them:

func getindexwithsuccess(success: (indexdata: nsdata!) -> void) {

more helpful links:

http://fuckingclosuresyntax.com

http://fuckingswiftblocksyntax.com

edit:

perhaps clearest explanation in context rearranging this:

func getindexwithsuccess(     success: (         data: [doctormodel]     )->(         void     ),     moreinfo: string = "this parameter, trailing closure technique wont work" ) {

the above complies. moreinfo parameter true. trailing closures won't work. rearranging parameters closure last, can use trailing closure technique.


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