为什么我不能将此字符串转换为 URL? [英] Why can't I convert this String to a URL?

问题描述

我有 x 2 个关于 url 和 webViews 的问题.

I have x 2 questions about urls and webViews.

问题 1:我有一个从 API 获取的字符串，它应该是一个 url.字符串是 https://godochurch.blob.core.windows.net/sermons/1031/30-1-2017-Vision Sunday-Devotion.mp3

Question 1: I have a string which I am getting from an API that is supposed to be a url. The string is https://godochurch.blob.core.windows.net/sermons/1031/30-1-2017-Vision Sunday-Devotion.mp3

尝试转换为 url 时，我得到了 nil.

When trying to convert to a url I'm getting nil.

代码如下:

if let sermonUrl = sermonUrl {

        if let url = URL(string: sermonUrl) {

            let requestObj = URLRequest(url: url)
            webView.loadRequest(requestObj)

        }
    }

我发现Vision"和Sunday"之间的空格是问题所在.

I have worked out that the space between 'Vision' and 'Sunday' is the problem.

在尝试将字符串转换为 URL 之前，我应该以某种方式对其进行编码吗?令人困惑的是，如果我将字符串粘贴到浏览器中，它就可以正常工作，但我注意到浏览器对空格进行了百分比编码.

Should I be encoding the string in some way before trying to convert it to a URL? What's confusing is that if I paste the string into my browser it works just fine, but I notice the browser is percent encoding the space.

如果我应该对字符串进行编码，我该怎么做?

If I am supposed to be encoding the string, how do I do that?

问题 2:我看到 URL(string: "urlStringHere") 仅适用于 iOS 10.我的应用程序需要适用于 iOS 9.如何转换上述代码使其适用于 iOS 9 和 10.

Question 2: I see that URL(string: "urlStringHere") is only available from iOS 10. My app needs to work for iOS 9. How can I convert the above code so it works on iOS 9 and 10.

提前感谢您的时间.

推荐答案

1: 用 %20 或 + 转义空间:

1: escape that space with %20 or +:

if let url = URL(string: "https://godochurch.blob.core.windows.net/sermons/1031/30-1-2017-Vision%20Sunday-Devotion.mp3") {
    // ...
}

2:URL 是在 Swift 3 中引入的，兼容 iOS 8 及更高版本.请参阅这个问题，了解如何使其适用于旧版本的 iOS.

2: URL was introduced with Swift 3, which is compatible with iOS 8 and later. See this question on how to make it work with older versions of iOS.

百分比转义 URL 的最简单方法是使用 URLComponents:

the easiest way to percent-escape a URL is to use URLComponents:

var components = URLComponents(string: "https://godochurch.blob.core.windows.net")!
components.path = "/sermons/1031/30-1-2017-Vision Sunday-Devotion.mp3"

if let url = components.url {
    // ... 
}

如果您碰巧从 Web 服务获取 URL 字符串并且其中包含空格，则该服务很糟糕.URL 中不允许有空格.Web 浏览器放宽了该规则，因为它们知道存在错误的 URL.斯威夫特不会接受.

If you happen to get you URL strings from a webservice and it contains a space, that service is bad. Space is not allowed in an URL. Web browsers relax that rule because they know there are bad URLs out there. Swift won't take it.

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