如何在Swift 3中将NSData转换为数据? [英] How to convert NSData to Data in Swift 3?

问题描述

我正在尝试创建一个简单的天气应用程序，该应用程序可以获取用户的位置并使用Google Maps api显示简单的天气数据.一切正常，除了这部分，我使用JSON并获取地址.

I'm trying to create a simple weather app that grabs the user's location and shows simple weather data using the Google Maps api. Everything is working, except for this part where I take the JSON and get the address.

func getAddressForLatLng(latitude: String, longitude: String) {
    let url = NSURL(string: "\(baseUrl)latlng=\(latitude),\(longitude)&key=\(apikey)")
    let data = NSData(contentsOf: url! as URL)
    let json = try! JSONSerialization.jsonObject(with: data, options: JSONSerialization.ReadingOptions.allowFragments) as! Dictionary
    if let result = json["results"] as? Dictionary {
        if let address = result[0]["address_components"] as? Array {
            let number = address[0]["short_name"] as! String
            let street = address[1]["short_name"] as! String
            let city = address[2]["short_name"] as! String
            let state = address[4]["short_name"] as! String
            let zip = address[6]["short_name"] as! String
            weatherDisplay.text = "\(city),\(state)"
        }
    }
}

在线:

let json = try! JSONSerialization.jsonObject(with: data, options: JSONSerialization.ReadingOptions.allowFragments) as! Dictionary 

我收到此错误:

Cannot invoke 'jsonObject' with an argument list of type '(with: NSData?, options: JSONSerialization.ReadingOptions)'

我在做什么错了?

推荐答案

您需要更改几件事.首先，您正在使用NSData.您应该使用Swift类型Data.要从NSData?转换为Data?，只需在变量声明的末尾添加as Data?.

You need to change a couple things. First, you are using NSData. You should be using the Swift type Data. To convert from NSData? to Data?, just add as Data? to the end of the variable declaration.

此外，您的类型是可选的，但是您不能传递可选的类型，因此需要解开它(在本示例中使用if let data = data { /* stuff here */}):

Also, Your type is optional, but you can't pass in an optional type, so you need to unwrap it (using, in this example, if let data = data { /* stuff here */}):

func getAddressForLatLng(latitude: String, longitude: String) {
    let url = NSURL(string: "\(baseUrl)latlng=\(latitude),\(longitude)&key=\(apikey)")
    let data = NSData(contentsOf: url! as URL) as Data? // <==== Added 'as Data?'
    if let data = data { // <====== Added 'if let'
        let json = try! JSONSerialization.jsonObject(with: data, options: JSONSerialization.ReadingOptions.allowFragments) as! Dictionary
        if let result = json["results"] as? Dictionary {
            if let address = result[0]["address_components"] as? Array {
                let number = address[0]["short_name"] as! String
                let street = address[1]["short_name"] as! String
                let city = address[2]["short_name"] as! String
                let state = address[4]["short_name"] as! String
                let zip = address[6]["short_name"] as! String
                weatherDisplay.text = "\(city),\(state)"
            }
        }
    }
}

更新:

您需要更改的另一件事是:

Another thing you need to change is:

let json = try! JSONSerialization.jsonObject(with: data, options: JSONSerialization.ReadingOptions.allowFragments) as! Dictionary

当您强制转换为类型Dictionary时，编译器不知道您在说什么，因为Dictionary是

When you cast to the type Dictionary, the compiler does not know what you are talking about because Dictionary is a generic type. So you need to cast to Dictionary<String, AnyObject> or [String: AnyObject] (They are the same).

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