转义完成处理程序永远不会发生（Google 地方 API）

Question

我正在构建一个使用 Google 地点 API 的应用。我目前有一个按钮，点击该按钮可获取当前 GPS 位置的地址。代码在我的视图控制器中：

var placesClient: GMSPlacesClient?

@IBAction func buttonTapped(_ sender: AnyObject) {
    placesClient?.currentPlace(callback: { (placeLikelihoods, error) -> Void in
        guard error == nil else {
            print("Current Place error: \(error!.localizedDescription)")
            return
        }

        if let placeLikelihoods = placeLikelihoods {
            let place = placeLikelihoods.likelihoods.first?.place
            self.addressLabel.text = place?.formattedAddress!.components(separatedBy: ", ").joined(separator: "\n")
        }
    })
    print("Out of the brackets...")
}

这样完成后，函数完成并打印 "Out of the brackets..."。

但是，当我尝试将此代码移出视图控制器并移入自定义 class 并从视图控制器调用它时，如下所示，"placesClient?.currentPlace(callback" 块中的所有内容都会运行（并且检索正确的地址），但 "Out of the brackets..." 永远不会被打印出来，它也永远不会 returns 值：

class LocationAPIService {
var placesClient: GMSPlacesClient? = GMSPlacesClient.shared()

func getCurrentLocation() -> GMSPlace? {
    var thisPlace: GMSPlace?

    placesClient?.currentPlace(callback: { (placeLikelihoods, error) -> Void in
        guard error == nil else {
            print("Current Place error: \(error!.localizedDescription)")
            return
        }

        if let placeLikelihoods = placeLikelihoods {
            let place = placeLikelihoods.likelihoods.first?.place
            thisPlace = place
        }
    })
    print("Out of the brackets...")
    return thisPlace
}
}

有人知道为什么会这样吗？

Answer 1

已修复。这是我在 LocationAPIService class:

中用于该方法的代码

func setCurrentLocationPlace(completion: @escaping (_ result: Bool)->()) {
    var placeFindComplete: Bool = false

    placesClient?.currentPlace(callback: { (placeLikelihoods, error) -> Void in
        guard error == nil else {
            print("Current Place error: \(error!.localizedDescription)")
            completion(true)
            return
        }

        if let placeLikelihoods = placeLikelihoods {
            let place = placeLikelihoods.likelihoods.first?.place
            self.currentPlace = place
            placeFindComplete = true
            completion(true)
        }
    })
    if (placeFindComplete == false) {
        completion(false)
    }
}

这是我从视图控制器中调用它的方式：

locationAPIService?.setCurrentLocationPlace() { (locationFound) -> () in
        if (locationFound == true) {
//Run code here that triggers once setCurrentLocationPlace() complete.
}

转义完成处理程序永远不会发生（Google 地方 API）

Escaping completion handler never happens (Google Places API)

google-places-api

google-places

swift