Returning a value from a function with Alamofire and SwiftyJson

问题

I have an app that returns a menu of information (basically menus, menu_headers, and items). I'd like to have something like this:

EKMenu.getMenu(menu_id: Int)

that would return a menu but I think I would need a completion handler in here.

I currently have:

class func getMenu(menu_id: Int){
//class func getMenu(menu_id: Int, completionHandler:(NSArray -> Void)){

  let url="https://www.example.com/arc/v1/api/menus/\(menu_id)/mobile"
  Alamofire.request(.GET, url).responseJSON() {
    (_, _, data, _) in
    println("within menu request")
    var json=JSON(data!)
    var menu=EKMenu()
    menu.name=json["menu"]["name"].stringValue
    for (key, subJson) in json["menu"]["menu_headers"]{
      EKMenu.processMenuHeaders(subJson)
    }
    // how would we return a value here ?????
  }
}

  class func processMenuHeaders(menu_header: JSON){
    let mh_name=menu_header["name"].stringValue
    println("mh_name: \(mh_name)")
    for (key, subJson) in menu_header["menu_headers"]{
      EKMenu.processMenuHeaders(subJson)
    }
  }

but how do I actually return something here? I am 99% sure that it's some type of completion handler but, being new to Swift and Alamofire, I'm a bit lost. I've seen I won't be able to return a value with Alamofire in Swift but know that some of this is going out of date very quickly (ie Swift 1.1)

回答1:

An example of a completion handler for your getMenu function, assuming menu is the value you want to "return":

class MenuManager {

    // the handler takes an EKMenu argument
    class func getMenu(menu_id: Int, completionHandler: (menu: EKMenu) -> ()) {

        let url="https://www.domain.com/arc/v1/api/menus/\(menu_id)/mobile"
        Alamofire.request(.GET, url).responseJSON() {
            (_, _, data, _) in
            println("within menu request")
            var json=JSON(data!)
            var menu=EKMenu()
            menu.name=json["menu"]["name"].stringValue
            for (key, subJson) in json["menu"]["menu_headers"]{
                EKMenu.processMenuHeaders(subJson)
            }

            // wrap the resulting EKMenu in the handler
            completionHandler(menu)

        }
    }

    class func processMenuHeaders(menu_header: JSON){
        let mh_name=menu_header["name"].stringValue
        println("mh_name: \(mh_name)")
        for (key, subJson) in menu_header["menu_headers"]{
            EKMenu.processMenuHeaders(subJson)
        }
    }

}

MenuManager.getMenu(42, completionHandler: { menu in
    // here the handler gives you back the value
    println(menu)
})

来源：https://stackoverflow.com/questions/30771881/returning-a-value-from-a-function-with-alamofire-and-swiftyjson

标签

swift

alamofire

swifty-json