SWIFT 2 全局变量不包含任何数据。在范围内有数据。

Question

全局变量不包含任何数据。 在范围内有数据。NSLog告诉我，我在函数GetJsonDataFromURL中的数据包含数据。

'请向我解释为什么以及处理变量和数据的行业标准方法是什么，现在已经调试了几天了"

var employeeData : Dictionary<String, AnyObject> = [:]
override func viewDidLoad() {
    super.viewDidLoad()
    GetJsonDataFromURL()
    NSLog("%@", employeeData) <- THIS LINE HAS NO DATA
}
func GetJsonDataFromURL() {
    let postEndpoint: String = "http://localhost/watsdis/showOutbox.php"
    let session = NSURLSession.sharedSession()
    let url = NSURL(string: postEndpoint)!
    var dataContainer : Dictionary <String, String> = [:]
    var mobiles : Dictionary <String, String> = [:]
    var msgs : Dictionary <String, String> = [:]
    var ids : [String] = []
    var names : Dictionary <String, String> = [:]
    var pos = ""
    // Make the POST call and handle it in a completion handler
    session.dataTaskWithURL(url, completionHandler: { ( data: NSData?, response: NSURLResponse?, let error: NSError?) -> Void in
        // Make sure we get an OK response
        guard let realResponse = response as? NSHTTPURLResponse where
                  realResponse.statusCode == 200 else {
            print("Not a 200 response")
                    return
        }
        // Read the JSON
        do {
            let json = try NSJSONSerialization.JSONObjectWithData(data!, options: .AllowFragments)
            if let employees = json["employee"] as? [[String: AnyObject]] {
                for employee in employees {
                    if let id = employee["id"] as? String {
                        ids.append (id)
                        pos = id
                    }
                    if let mobile = employee["mobile"] as? String {
                        mobiles[pos] = mobile
                    }
                    if let msg = employee["msg"] as? String {
                        msgs[pos] = msg
                    }
                    if let name = employee["name"] as? String {
                        names[pos] = name
                    }
                }
            }
            self.employeeData["id"] = ids
            self.employeeData["name"] = names
            self.employeeData["mobile"] = mobiles
            self.employeeData["msg"] = msgs
       } catch {
            print("error serializing JSON: (error)")
        }
        NSLog("%@", self.employeeData) <- THIS LINE DISPLAYS MY DATA IN ARRAY FORMAT
    }).resume();
}

Answer 1

GetJsonDataFromURL是异步函数在viewDidLoad中，您调用：

GetJsonDataFromURL()
NSLog("%@", employeeData) <- THIS LINE HAS NO DATA

NSLog 在函数 GetJsonDataFromURL 返回数据之前运行，因此它是空数据。你试试：

func GetJsonDataFromURL(handleComplete:(isOK:Bool)->()) {
    let postEndpoint: String = "http://localhost/watsdis/showOutbox.php"
    let session = NSURLSession.sharedSession()
    let url = NSURL(string: postEndpoint)!
    var dataContainer : Dictionary <String, String> = [:]
    var mobiles : Dictionary <String, String> = [:]
    var msgs : Dictionary <String, String> = [:]
    var ids : [String] = []
    var names : Dictionary <String, String> = [:]
    var pos = ""
    // Make the POST call and handle it in a completion handler
    session.dataTaskWithURL(url, completionHandler: { ( data: NSData?, response: NSURLResponse?, let error: NSError?) -> Void in
        // Make sure we get an OK response
        guard let realResponse = response as? NSHTTPURLResponse where
            realResponse.statusCode == 200 else {
                print("Not a 200 response")
                return
        }
        // Read the JSON
        do {
            let json = try NSJSONSerialization.JSONObjectWithData(data!, options: .AllowFragments)
            if let employees = json["employee"] as? [[String: AnyObject]] {
                for employee in employees {
                    if let id = employee["id"] as? String {
                        ids.append (id)
                        pos = id
                    }
                    if let mobile = employee["mobile"] as? String {
                        mobiles[pos] = mobile
                    }
                    if let msg = employee["msg"] as? String {
                        msgs[pos] = msg
                    }
                    if let name = employee["name"] as? String {
                        names[pos] = name
                    }
                }
            }
            self.employeeData["id"] = ids
            self.employeeData["name"] = names
            self.employeeData["mobile"] = mobiles
            self.employeeData["msg"] = msgs
            handleComplete(isOK: true)
        } catch {
            handleComplete(isOK: false)
            print("error serializing JSON: (error)")
        }
        NSLog("%@", self.employeeData) <- THIS LINE DISPLAYS MY DATA IN ARRAY FORMAT
    }).resume();
}

并在viewDidLoad

self.GetJsonDataFromURL { (isOK) -> () in
        if isOK{
            print(self.employeeData)
        }else{
            print("error")
        }
    }

Answer 2

您正在使用回调调用异步方法。很有可能在执行将数据放入 employeeData 的回调之前检查变量。