为什么会出现 URL 错误？

Question

我正在使用 iTunes 搜索 API，为了测试，我正在搜索 "Angry Birds" 并打印结果。但是当我将 urlPath 转换为 NSURL 时，我得到了一个 nil 值。我该如何解决？ urlPath 有 link，但它在 url 变量中是 nil。这是确切的错误：

fatal error: unexpectedly found nil while unwrapping an Optional value.

var searchTerm: String = "Angry Birds"
var itunesSearchTerm = searchTerm.stringByReplacingOccurrencesOfString(" ", withString: "+", options: NSStringCompareOptions.CaseInsensitiveSearch, range: nil)
var escapedSearchTerm = itunesSearchTerm.stringByAddingPercentEscapesUsingEncoding(NSUTF8StringEncoding)
var urlPath = "https://itunes.apple.com/search?term=\(escapedSearchTerm)&media=software"
var url: NSURL = NSURL(string: urlPath)!
var request: NSURLRequest = NSURLRequest(URL: url)
var connection: NSURLConnection = NSURLConnection(request: request, delegate: self, startImmediately: false)!

print("Search iTunes API at URL \(url)")

connection.start()

Answer 1

NSURL returns nil 当 URL 包含非法字符如 space 时。验证您的 URlString 是否正确。

Answer 2

stringByAddingPercentEscapesUsingEncoding returns 一个可选的字符串，所以你得到的实际上是这样的：

https://itunes.apple.com/search?term=Optional("Angry+Birds")&media=software

解决方案是安全地解包 Optional:

if let escapedSearchTerm = itunesSearchTerm.stringByAddingPercentEscapesUsingEncoding(NSUTF8StringEncoding) {
    let urlPath = "https://itunes.apple.com/search?term=\(escapedSearchTerm)&media=software"
    let url = NSURL(string: urlPath)
    // ...
}

结果：

https://itunes.apple.com/search?term=Angry+Birds&media=software

为什么会出现 URL 错误？

Why is the URL error occurring?

nsurl

foundation

swift

itunes-api