调用

Question

我有以下基本代码结构：

self.ok_today = 0
checkToday("Daily Steps")
if (self.ok_today == 0) {}

我的问题是这些操作没有按顺序执行。当我运行它时，我的变量初始化为0，然后执行if块，然后执行checkToday()方法。 （因为我的变量永远不会增加，所以它总是转到if块）

这是checkToday方法，它使用Alamofire获取一些数据：

func checkToday(concept: String) {

        let user = "***"
        let password = "***"

        let credentialData = "\(user):\(password)".dataUsingEncoding(NSUTF8StringEncoding)!
        let base64Credentials = credentialData.base64EncodedStringWithOptions([])

        let headers = ["Authorization": "Basic \(base64Credentials)"]

       Alamofire
        .request(.GET, "http://***/ws/fhir/Observation?date="+self.todayStepsDate+"T00:00:00", headers: headers)
        .responseJSON { response in
            var json = JSON(response.result.value!)
            var i = 0
            while (json["entry"][i]["resource"]["valueQuantity"]["value"] != nil) {

                // Checks if the user synced his data for current day
                if (json["entry"][i]["resource"]["code"]["coding"][0]["display"].rawString() == concept){
                    let patientAux: String = "Patient/"+self.person_uuid
                    if (json["entry"][i]["resource"]["subject"]["reference"].rawString() == patientAux){
                        self.ok_today = self.ok_today+1
                    }
                }
                i=i+1
            }
        }
    }

知道为什么我会遇到这个问题吗？

Answer 1

Alamofire请求是异步的。你应该使用回调。将代码更改为此以获得所需的功能。

func checkToday(concept: String, callback: () -> ()) {

        let user = "***"
        let password = "***"

        let credentialData = "\(user):\(password)".dataUsingEncoding(NSUTF8StringEncoding)!
        let base64Credentials = credentialData.base64EncodedStringWithOptions([])

        let headers = ["Authorization": "Basic \(base64Credentials)"]

       Alamofire
        .request(.GET, "http://***/ws/fhir/Observation?date="+self.todayStepsDate+"T00:00:00", headers: headers)
        .responseJSON { response in
            var json = JSON(response.result.value!)
            var i = 0
            while (json["entry"][i]["resource"]["valueQuantity"]["value"] != nil) {

                // Checks if the user synced his data for current day
                if (json["entry"][i]["resource"]["code"]["coding"][0]["display"].rawString() == concept){
                    let patientAux: String = "Patient/"+self.person_uuid
                    if (json["entry"][i]["resource"]["subject"]["reference"].rawString() == patientAux){
                        self.ok_today = self.ok_today+1
                    }
                }
                i=i+1
            }
            //code is done, now call the callback
            callback()
        }
    }

并像这样使用

self.ok_today = 0
checkToday("Daily Steps") {
    //callback is called
    if (self.ok_today == 0) {}
}