如何在 Swift 中解码 HTML 实体?

问题描述

我正在从站点提取 JSON 文件，收到的字符串之一是:

I am pulling a JSON file from a site and one of the strings received is:

The Weeknd ‘King Of The Fall’ [Video Premiere] | @TheWeeknd | #SoPhi

如何将 &#8216 之类的内容转换为正确的字符?

How can I convert things like &#8216 into the correct characters?

我制作了一个 Xcode Playground 来演示它:

I've made a Xcode Playground to demonstrate it:

import UIKit

var error: NSError?
let blogUrl: NSURL = NSURL.URLWithString("http://sophisticatedignorance.net/api/get_recent_summary/")
let jsonData = NSData(contentsOfURL: blogUrl)

let dataDictionary = NSJSONSerialization.JSONObjectWithData(jsonData, options: nil, error: &error) as NSDictionary

var a = dataDictionary["posts"] as NSArray

println(a[0]["title"])

推荐答案

此答案最后修订为 Swift 5.2 和 iOS 13.4 SDK.

没有直接的方法可以做到这一点，但您可以使用 NSAttributedString 魔法使这个过程尽可能轻松(请注意，此方法也会删除所有 HTML 标签).

There's no straightforward way to do that, but you can use NSAttributedString magic to make this process as painless as possible (be warned that this method will strip all HTML tags as well).

记住只从主线程初始化NSAttributedString.它使用 WebKit 来解析下面的 HTML，因此需要.

Remember to initialize NSAttributedString from main thread only. It uses WebKit to parse HTML underneath, thus the requirement.

// This is a[0]["title"] in your case
let encodedString = "The Weeknd <em>&#8216;King Of The Fall&#8217;</em>"

guard let data = htmlEncodedString.data(using: .utf8) else {
    return
}

let options: [NSAttributedString.DocumentReadingOptionKey: Any] = [
    .documentType: NSAttributedString.DocumentType.html,
    .characterEncoding: String.Encoding.utf8.rawValue
]

guard let attributedString = try? NSAttributedString(data: data, options: options, documentAttributes: nil) else {
    return
}

// The Weeknd ‘King Of The Fall’
let decodedString = attributedString.string

extension String {

    init?(htmlEncodedString: String) {

        guard let data = htmlEncodedString.data(using: .utf8) else {
            return nil
        }

        let options: [NSAttributedString.DocumentReadingOptionKey: Any] = [
            .documentType: NSAttributedString.DocumentType.html,
            .characterEncoding: String.Encoding.utf8.rawValue
        ]

        guard let attributedString = try? NSAttributedString(data: data, options: options, documentAttributes: nil) else {
            return nil
        }

        self.init(attributedString.string)

    }

}

let encodedString = "The Weeknd <em>&#8216;King Of The Fall&#8217;</em>"
let decodedString = String(htmlEncodedString: encodedString)

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