Question

我在以下功能中有完成处理程序

static func fetchFeatureApp(completionHandler:@escaping ([AppCategory1])->()){
        let urlString="http://ebmacs.net/ubereats/Api/all_product?id=1"
        let url = URL(string: urlString)!

     URLSession.shared.dataTask(with: URLRequest(url: url)){ (data, responce, error) in
        if error != nil
            {
                print(error)
                return
            }
        do {
            if let jsonResult = try JSONSerialization.jsonObject(with:data!) as? [String:Any] {
                if let products = jsonResult["products"] as? [[String:String]] {
                    var appCategories = [AppCategory1]()
                    for product in products {
                        let category = AppCategory1(id: product["product_id"] ?? "",
                                                   name: product["product_name"] ?? "",
                                                   description: product["product_description"] ?? "",
                                                   url: product["image_url"] ?? "",
                                                   price: product["product_price"] ?? "")
                        appCategories.append(category)
                    }
                     print("Abc=")
                    print(appCategories)
                    dispatch_async(dispatch_get_main_queue(), {
                        completionHandler(appCategories)
                    })

                }
            }
        } catch {
            print(error)
        }
        }.resume()

    }

上述函数中的dispatch async给出了错误

  dispatch_async(dispatch_get_main_queue(), {
                    completionHandler(appCategories)
                })

错误陈述是

'dispatch_async'已被实例方法取代 'DispatchQueue.async（执行:)' 'dispatch_get_main_queue（）'已被属性取代 'DispatchQueue.main'

如何更正此错误？

我调用此函数

 AppCategory.fetchFeatureApp { (appcategories) in
            self.appcategories = appcategories
            self.collectionView?.reloadData()
        }

给出错误

'FeaturedViewController'类型的值没有成员'appcategories'

如何纠正函数调用？

Answer 1

这是现代（Swift 3及更高版本）语法：

DispatchQueue.main.async { completionHandler(appCategories) }

完成处理程序dispatch_async出错？

1 个答案: