NSString编码在url内容上返回nil [英] NSString encoding returns nil on url content

问题描述

我正在关注Udemy的iOS Swift指南，这是我无法解决的第一个问题：

I'm following an iOS Swift guide on Udemy and this is the first issue I cannot work around:

我应该看到html等打印到控制台但我得到了空。

I am supposed to see html etc printed to the console but instead I get null.

这是一节：

    let url = NSURL(string: "https://google.com")
    let task = NSURLSession.sharedSession().dataTaskWithURL(url!) {
        (data, response, error) in
        if error == nil {
            var urlContent = NSString(data: data!, encoding: NSUTF8StringEncoding)
            print(urlContent)
        }
    } 
    task.resume()

如果我只打印数据然后它会给我一些内容，但当它编码时没有。

If I print just the data then it gives me some content back but when its encoded its nil.

任何帮助？在解决之前无法进入下一部分。

Any help? Cannot move onto the next part until this is resolved.

推荐答案

rmaddy已经提到的问题是你的编码使用。您需要使用 NSASCIIStringEncoding 。

The problem there as already mentioned by rmaddy it is the encoding you are using. You need to use NSASCIIStringEncoding.

if let url = URL(string: "https://www.google.com") {
    URLSession.shared.dataTask(with: url) {
        data, response, error in
        guard
            let httpURLResponse = response as? HTTPURLResponse, httpURLResponse.statusCode == 200,
            let data = data, error == nil,
            let urlContent = String(data: data, encoding: .ascii)
        else { return }
        print(urlContent)
    }.resume()
}

或者从Martin R中获取线索，您可以从响应中检测字符串编码：

Or taking a clue from Martin R you can detect the string encoding from the response:

extension String {
    var textEncodingToStringEncoding: Encoding {
        return Encoding(rawValue: CFStringConvertEncodingToNSStringEncoding(CFStringConvertIANACharSetNameToEncoding(self as CFString)))
    }
}

---

---

if let url = URL(string: "https://www.google.com") {
    URLSession.shared.dataTask(with: url) {
        data, response, error in
        guard
            let httpURLResponse = response as? HTTPURLResponse, httpURLResponse.statusCode == 200,
            let data = data, error == nil,
            let textEncoding = response?.textEncodingName,
            let urlContent = String(data: data, encoding: textEncoding.textEncodingToStringEncoding)
            else { return }
        print(urlContent)
    }.resume()
}

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