如何同步調用CLGeocoder方法

Question

我在ViewController代碼中

var location = CLLocation()
    DispatchQueue.global().sync {
        let objLocationManager = clsLocationManager()
        location = objLocationManager.findLocationByAddress(address: self.txtTo.stringValue)
    }
    lblToLatitude.stringValue = String(location.coordinate.latitude)
    lblToLongitude.stringValue = String(location.coordinate.longitude)

調用在單獨的類clsLocationManager中實現的findLocationByAddress方法，如下所示

func findLocationByAddress(address: String) -> CLLocation {
    let geoCoder = CLGeocoder()
    var location = CLLocation()
    geoCoder.geocodeAddressString(address, completionHandler: {(places, error) in
        guard error == nil else { return }
        location = places![0].location!
    })
    return location
}

我嘗試通過DispatchQueue.global（）。sync確保在將坐標傳遞給lblToLatitude和lblToLongitude標簽之前執行了地理編碼，但是它不起作用。 當然，我可以在ViewController代碼中進行地理編碼，但是我想知道如何將其保留在單獨的類中。

Answer 1

你需要完成

func findLocationByAddress(address: String,completion:@escaping((CLLocation?) -> ())) {
    let geoCoder = CLGeocoder() 
    geoCoder.geocodeAddressString(address, completionHandler: {(places, error) in
        guard error == nil else { completion(nil) ; return }
        completion(places![0].location!)
    }) 
}

打電話

findLocationByAddress { (location) in 
  if let location = location { 
      lblToLatitude.stringValue = String(location.coordinate.latitude)
      lblToLongitude.stringValue = String(location.coordinate.longitude)
  } 
}

同樣也不需要DispatchQueue.global().sync {因為地址解析器在后台線程中異步運行