Question

我有一个很大的JSON列表，我下载的项目，我相信是异步（好），但当我循环通过JSON将它们变成对象（“产品”对象准确），整个应用程序冻结为for循环执行。

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self.dm.getOrderGuideData({ (time: CFAbsoluteTime) in
     self.dm.parseInOrderGuideProducts({ (completion: Bool) in
     })
})

我把它们放在封闭物中以防止这种情况，但它似乎没有起作用。

func getOrderGuideData(completion: (time: CFAbsoluteTime) -> ()) {
        let startTime = CFAbsoluteTimeGetCurrent()

        Alamofire.request(.POST, "https://sysco-dev.madmobile.com/api/products.pricing", parameters: orderGuideRequest, encoding: .JSON) .responseJSON { (req, res, json, error) in

            if error != nil  {
                println("\n\nOG ERROR: \(error!)\n\n")
                println(req)
                println(res)

                let endTime = CFAbsoluteTimeGetCurrent() - startTime
                completion(time: endTime)
            }
            else {

                var jsonForError = JSON(json!)
                if jsonForError["errors"] != nil {
                    println("Order Guide Success")

                    self.rawOrderGuideJSON = json

                    let endTime = CFAbsoluteTimeGetCurrent() - startTime
                    completion(time: endTime)
                }
                else {
                    var error = jsonForError["errors"]
                    println(error)
                    let endTime = CFAbsoluteTimeGetCurrent() - startTime
                    completion(time: endTime)
                }
            }
        }
    }

    func parseInOrderGuideProducts(completion: Bool -> ()) {
        var parsedJSON = JSON(rawOrderGuideJSON!)

        var resultset = parsedJSON["resultset"]
        for (key, subJson) in resultset {
            println(key)

            var newProduct: Product = Product()

            newProduct.title = key as String
//            newProduct.id = parsedJSON["resultset"][key]["materialId"].string
//            newProduct.image = getOrderGuidePhotoForID(newProduct.id!)
            newProduct.id = resultset[key]["materialId"].string
            var price = resultset[key]["price"].double
            newProduct.price = "$\(price!)"
            newProduct.weight = resultset[key]["totalWeight"].string

            orderGuideItemsList.append(newProduct)
        }
        completion(true)
    }

关于如何解决此问题的任何想法？当打印键时，控制台的输出会正常滚动（请参阅parseInOrderGuideProducts），但手机或模拟器上的执行会停止。

Answer 1

我通过使用dispatch_async显式调用for循环作为异步来解决我的问题。然后我再次调用主线程进行闭包并更改我的bool标志。

func parseInOrderGuideProducts(completion: Bool -> ()) {
    var parsedJSON = JSON(rawOrderGuideJSON!)

    var resultset = parsedJSON["resultset"]

    let priority = DISPATCH_QUEUE_PRIORITY_DEFAULT
    dispatch_async(dispatch_get_global_queue(priority, 0)) {

        for (key, subJson) in resultset {
            println(key)

            var newProduct: Product = Product()

            newProduct.title = key as String
            newProduct.id = resultset[key]["materialId"].string
            var price = resultset[key]["price"].double
            newProduct.price = "$\(price!)"
            newProduct.weight = resultset[key]["totalWeight"].string
            newProduct.image = self.getOrderGuidePhotoForID(newProduct.id!)

            self.orderGuideItemsList.append(newProduct)
        }

        dispatch_async(dispatch_get_main_queue()) {
            completion(true)
            self.finishedPopulatingOrderGuide = true
        }
    }
}

在Swift暂停执行中Async For Loop？

1 个答案: