swift - 在进行 POST 之前等待找到坐标

Question

我正在使用 CLGeocoder 获取用户输入的地址的坐标，该地址将被发送到服务器。但是这个在 POST 到服务器之前调用的函数花费了很长时间，以至于服务器已经发送了信息并且在找到坐标之前已经回复了。我如何等待此函数完成并通知调用它的方法它可以继续？

func getCoordinates(address: String){

    let geoCoder = CLGeocoder()

         geoCoder.geocodeAddressString(address, completionHandler: { (placemarks, error) in

            let placemark = placemarks?.first
            self.lat = String(format: "%f",(placemark?.location?.coordinate.latitude)!)
            self.lon = String(format: "%f",(placemark?.location?.coordinate.longitude)!)

            print("Lat: \(self.lat), Lon: \(self.lon)")
        })

}

我查看了 UNUserNotificationCenter 和 DispatchGroup 但没有用...？

Answer 1

有很多方法可以做到这一点。例如你调用Swift Closure检索坐标后。

func getCoordinates(address: String, completionHandler:()->()){

    let geoCoder = CLGeocoder()

    geoCoder.geocodeAddressString(address, completionHandler: { (placemarks, error) in

        let placemark = placemarks?.first
        self.lat = String(format: "%f",(placemark?.location?.coordinate.latitude)!)
        self.lon = String(format: "%f",(placemark?.location?.coordinate.longitude)!)

        print("Lat: \(self.lat), Lon: \(self.lon)")
        completionHandler() //call Swift Closure after retrieving coordinates.
    })

}

//USAGE
getCoordinates(address: "address",
               completionHandler:{
                print("Lat: \(self.lat), Lon: \(self.lon)")
                //execute POST query here <===
})