Question

我具有请求功能，并且在获取JSON之后。我将数据解析为结构实例。我如何从函数中返回该实例？现在它返回的是nil变量。

获取JSON并将其解析为结构正常运行，返回实例时出现问题。

class FinantialRequest {

        static func getData(id: Int, year: Int, mod : String, period: String)->CinemaChartModel{

            let parameters: Parameters = [
                "idc": id,
                "yy": year,
                "func": mod
            ]
            var chartModelSample = CinemaChartModel()
            request("https://placeholder.com/app.php", method: .post, parameters: parameters, encoding: URLEncoding.default).debugLog().responseJSON { responseJSON in
                switch responseJSON.result {
                case .success(let value):
                    do {
                        let parsedData = try FirebaseDecoder().decode(FinDataSample.self, from: value)
                        parsedData.data.forEach { sample in

                            switch sample.b.name {
                                case "Оборот кино":
                                    switch finantialDataSample.period! {
                                        case "1 Квартал":
                                            chartModelSample.moneyPeriodCinema = sample.k1
                                            chartModelSample.moneyBudgetPeriodCinema = sample.b.k1
                                        case "2 Квартал":
                                            chartModelSample.moneyPeriodCinema = sample.k2
                                            chartModelSample.moneyBudgetPeriodCinema = sample.b.k2
                                        case "3 Квартал":
                                            chartModelSample.moneyPeriodCinema = sample.k3
                                            chartModelSample.moneyBudgetPeriodCinema = sample.b.k3
                                        case "4 Квартал":
                                            chartModelSample.moneyPeriodCinema = sample.k4
                                            chartModelSample.moneyBudgetPeriodCinema = sample.b.k4
                                        default: break
                                        }
                                chartModelSample.moneyYyCinema = sample.yy
                                chartModelSample.moneyBudgetYyCinema = sample.b.yy
                            case "Количество людей":
                                switch finantialDataSample.period! {
                                    case "1 Квартал":
                                        chartModelSample.peoplePeriodCinema = sample.k1
                                        chartModelSample.peopleBudgetPeriodCinema = sample.b.k1
                                    case "2 Квартал":
                                        chartModelSample.peoplePeriodCinema = sample.k2
                                        chartModelSample.peopleBudgetPeriodCinema = sample.b.k2
                                    case "3 Квартал":
                                        chartModelSample.peoplePeriodCinema = sample.k3
                                        chartModelSample.peopleBudgetPeriodCinema = sample.b.k3
                                    case "4 Квартал":
                                        chartModelSample.peoplePeriodCinema = sample.k4
                                        chartModelSample.peopleBudgetPeriodCinema = sample.b.k4
                                    default: break
                                    }
                                chartModelSample.peopleYyCinema = sample.yy
                                chartModelSample.peopleBudgetYyCinema = sample.b.yy
                            default:
                                break
                        }
                    }

                } catch let error {
                    print(error)
                }
            case .failure(let error):
                print(error)
            }
        }
            return chartModelSample
        }

Answer 1

由于请求方法本身是关闭，因此您不能直接从中返回。您需要这样的完成处理程序：

static func getData(id: Int, year: Int, mod : String, period: String, completion: ((CinemaChartModel?)->Void)){

 .............

}

并使用如下结构触发它：

completion(chartModelSample)

或者如果没有返回值，则可以使用nil值触发它

completion(nil)

您可以这样调用此方法：

getData(id: Int, year: Int, mod : String, period: String, completion:{ (model) -> Void in
    .......
})

从Swift 4函数返回结构

1 个答案: