Swift：类型的值没有成员，不能调用非函数类型的值

Question

我正在按照关于 Ray Wenderlich 的教程在我的假期应用程序中创建一些功能，因此我创建了这个类：

import Foundation
import Foundation
import CoreLocation
import SwiftyJSON

class GoogleDataProvider {
    var photoCache = [String:UIImage]()
    var placesTask: URLSessionDataTask?
    var session: URLSession {
        return NSURLSession.sharedSession()
    }

    func fetchPlacesNearCoordinate(coordinate: CLLocationCoordinate2D, radius: Double, types:[String], completion: (([GooglePlace]) -> Void)) -> ()
    {
        var urlString = "http://localhost:10000/maps/api/place/nearbysearch/json?location=\(coordinate.latitude),\(coordinate.longitude)&radius=\(radius)&rankby=prominence&sensor=true"
        let typesString = types.count > 0 ? types.joined(separator: "|") : "food"
        urlString += "&types=\(typesString)"
        urlString = urlString.stringByAddingPercentEncodingWithAllowedCharacters(NSCharacterSet.URLQueryAllowedCharacterSet())!

        if let task = placesTask, task.taskIdentifier > 0 && task.state == .Running {
            task.cancel()
        }

        UIApplication.sharedApplication().networkActivityIndicatorVisible = true
        placesTask = session.dataTaskWithURL(NSURL(string: urlString)!) {data, response, error in
            UIApplication.sharedApplication().networkActivityIndicatorVisible = false
            var placesArray = [GooglePlace]()
            if let aData = data {
                let json = JSON(data:aData, options:NSJSONReadingOptions.MutableContainers, error:nil)
                if let results = json["results"].arrayObject as? [[String : AnyObject]] {
                    for rawPlace in results {
                        let place = GooglePlace(dictionary: rawPlace, acceptedTypes: types)
                        placesArray.append(place)
                        if let reference = place.photoReference {
                            self.fetchPhotoFromReference(reference) { image in
                                place.photo = image
                            }
                        }
                    }
                }
            }
            dispatch_async(dispatch_get_main_queue()) {
                completion(placesArray)
            }
        }
        placesTask?.resume()
    }


    func fetchPhotoFromReference(reference: String, completion: ((UIImage?) -> Void)) -> () {
        if let photo = photoCache[reference] as UIImage? {
            completion(photo)
        } else {
            let urlString = "http://localhost:10000/maps/api/place/photo?maxwidth=200&photoreference=\(reference)"
            UIApplication.sharedApplication().networkActivityIndicatorVisible = true
            session.downloadTaskWithURL(NSURL(string: urlString)!) {url, response, error in
                UIApplication.sharedApplication().networkActivityIndicatorVisible = false
                if let url = url {
                    let downloadedPhoto = UIImage(data: NSData(contentsOfURL: url)!)
                    self.photoCache[reference] = downloadedPhoto
                    dispatch_async(dispatch_get_main_queue()) {
                        completion(downloadedPhoto)
                    }
                }
                else {
                    dispatch_async(dispatch_get_main_queue()) {
                        completion(nil)
                    }
                }
                }.resume()
        }
    }
}

但我有两个错误。

对于这一行：

 urlString = urlString.stringByAddingPercentEncodingWithAllowedCharacters(NSCharacterSet.URLQueryAllowedCharacterSet())!

我得到了错误：

'String' 类型的值没有成员 'stringByAddingPercentEncodingWithAllowedCharacters'

在这一行：

UIApplication.sharedApplication().networkActivityIndicatorVisible = true

我得到了错误：

不能调用非函数类型的值'UIApplication'

我试图在网上寻找解决这些问题的方法，但没有。谁能告诉我如何调整这些？

Answer 1

这些函数名随着 Swift 3 的变化而改变。对于第一个，你应该使用String.addingPercentEncoding(withAllowedCharacters:)：

urlString = urlString.addingPercentEncoding(withAllowedCharacters: .urlQueryAllowed)

另外，UIApplication.sharedApplication() 变成了 UIApplication.shared 和 networkActivityIndicatorVisible 有一个 is 前缀，类似于 Swift 3 中的其他布尔值：

UIApplication.shared.isNetworkActivityIndicatorVisible = true