Question

我正在通过一组纬度和经度坐标进行反向地理编码。反向地理编码工作，我收回我的地址数据，但我需要从该数据创建一个URL，我做了更进一步。我发现的是NSURLSession在我获取数据之前正在执行。您可以看到我在println中放置的位置显示“first”和“second”，但是在执行此代码的输出控制台中，“second”显示然后“first”以及地址数据，这告诉我'我没有按顺序跑。

如何强制执行命令，要求在NSURLSession运行之前存在变量addchunk？

谢谢！

@IBAction func grabData(sender: UIButton) {
    var latitude:CLLocationDegrees = (latitudeEntry.text as NSString).doubleValue
    var longitude:CLLocationDegrees = (longitudeEntry.text as NSString).doubleValue
    var location = CLLocation(latitude: latitude, longitude: longitude)

    // reverse geocodes the supplied latitude and longitude
    CLGeocoder().reverseGeocodeLocation(location, completionHandler: {
        (placemarks, error) -> Void in
        if error != nil {
            println("Reverse geocoder failed with error" + error.localizedDescription)
        }
        if placemarks.count > 0 {
            let pm = placemarks[0] as CLPlacemark
            self.addchunk = "\(pm.subThoroughfare)-\(pm.thoroughfare),-\(pm.locality),-\(pm.administrativeArea)".lowercaseString
            println("first " + self.addchunk)
        } else {
            println("Problem with the data received from geocoder")
        }
    })

    var url = NSURL(string: "http://www.example.com/" + addchunk)
    println("second " + addchunk)
    if url != nil {
        let task = NSURLSession.sharedSession().dataTaskWithURL(url!, completionHandler: {
            (data, response, error) -> Void in
    ...

Answer 1

更新您的代码：

var latitude:CLLocationDegrees = ("-34.4232722" as NSString).doubleValue
    var longitude:CLLocationDegrees = ("150.8865837" as NSString).doubleValue
    var location = CLLocation(latitude: latitude, longitude: longitude)

    // reverse geocodes the supplied latitude and longitude
    CLGeocoder().reverseGeocodeLocation(location, completionHandler: {
        (placemarks, error) -> Void in
        if error != nil {
            println("Reverse geocoder failed with error" + error.localizedDescription)
        }
        if placemarks.count > 0 {
            let pm = placemarks[0] as CLPlacemark
            self.addchunk = "\(pm.subThoroughfare)-\(pm.thoroughfare),-\(pm.locality),-\(pm.administrativeArea)".lowercaseString
            println("first " + self.addchunk)
        } else {
            println("Problem with the data received from geocoder")
        }
        var url = NSURL(string: "http://www.example.com/" + self.addchunk)
        println("second " + self.addchunk)
        if url != nil {
            let task = NSURLSession.sharedSession().dataTaskWithURL(url!, completionHandler: {
                (data, response, error) -> Void in
            })
        }
    })

我已经测试了这个并且工作正常。这是我坐标的输出：

first 18-hercules street,-wollongong,-nsw
second 18-hercules street,-wollongong,-nsw

Swift中的同步代码执行

1 个答案: