ios - 从 ViewController 调用时如何检索存储在单独类中的数据？

Question

我目前正在学习使用 Swift 进行 iOS 开发。我正在制作一个简单的天气应用程序。我有几个按钮可以获取接下来 4 小时的天气。我从 dark sky API 获取天气，以 JSON 格式返回。我终于想出了如何从 JSON 中检索正确的数据，并创建了一个获取数据的类。

typealias WeatherCallback = (Weather) -> Void
typealias ErrorCallback = (Error) -> Void

class NetworkManager {

    class func getWeather(latitude: String, longitude: String, onSuccess: WeatherCallback? = nil, onError: ErrorCallback? = nil) {

        let urlString = "https://api.darksky.net/forecast/(api key)/" + latitude + "," + longitude + "?units=si"

        let url = URL(string: urlString)

        URLSession.shared.dataTask(with: url!) { (data, response, error) in
            if error != nil {
                print(error!)
                onError?(error!)
            } else {
                do {
                    let json  = JSON(data: data!)
                    let weather = Weather()

                    DispatchQueue.main.async {
                        weather.updateWithJSON(dict: json["currently"], hour: 0)

                        for i in 1...4 {
                            weather.updateWithJSON(dict: json["hourly"]["data"][i], hour: i)
                        }
                    }
                    onSuccess?(weather) 
                }
            }
            }.resume()
    }
}

我有一个不同的类来存储检索到的数据。

class Weather {

    public var currentTime: String = ""
    public var currentTemperature: String = ""

    public var nextHourTime: String = ""
    public var nextHourTemperature: String = ""

    public var nextTwoHourTime: String = ""
    public var nextTwoHourTemperature: String = ""

    public var nextThreeHourTime: String = ""
    public var nextThreeHourTemperature: String = ""

    public var nextFourHourTime: String = ""
    public var nextFourHourTemperature: String = ""

    func updateCurrentData(time: String, temp: String) {
        currentTime = time
        currentTemperature = temp
    }

    func updateWithJSON(dict: JSON, hour: Int){

        switch hour {
        case 0:
            currentTime = dict["time"].stringValue
            currentTemperature = dict["temperature"].stringValue

        case 1:
            nextHourTime = dict["time"].stringValue
            nextHourTemperature = dict["temperature"].stringValue

        case 2:
            nextTwoHourTime = dict["time"].stringValue
            nextTwoHourTemperature = dict["temperature"].stringValue

        case 3:
            nextThreeHourTime = dict["time"].stringValue
            nextThreeHourTemperature = dict["temperature"].stringValue

        case 4:
            nextFourHourTime = dict["time"].stringValue
            nextFourHourTemperature = dict["temperature"].stringValue

        default:
            print("rip")
        }
    }
}

我的问题是，我无法从 ViewController 中访问类 Weather 中的存储值。

例如

let weather = Weather()

print(weather.currentTime)

如果能帮我指明正确的方向，那就太棒了!谢谢!

Answer 1

您可以通过创建 Weather 类 Singleton 来实现。使用单例 此对象仅存在一个副本，并且状态由任何其他对象共享和访问。

class Weather {
public static var sharedInstance =  Weather()
...
private init() {
}
}

然后像这样获取单例对象

let weather = Weather.sharedInstance // it will give you the same instance of Weather every time you call it.