无法将'subSequence'类型的值(也称为'String.CharacterView')转换为在集合中键入'String'

Question

我构建了一个从数据库中请求图像URL的webservis.而我想在迅速展示它.但是我在var photo line上发现了这个错误:

无法将'subSequence'类型的值(也称为'String.CharacterView')转换为在集合中键入'String'

let requestResponse = self.sendToServer(postUrl: "localhost",data:"abc")

let Seperated = requestResponse.characters.split(separator: " ")

var photo = Seperated[0] as String

let imageURL = URL(string: photo)
if let imageData = try? Data(contentsOf: imageURL!) {
    ...
}

Answer 1

考虑这样的事情:

let requestResponse = "some string"
let separated = requestResponse.characters.split(separator: " ")

if let some = separated.first {
    let value = String(some)

    // Output: "some"
}

Answer 2

最简单的解决方案。

let separated = requestResponse.characters.split(separator: " ").map { String($0) }

Answer 3

split返回 s 的列表Substring，因此我们必须将它们映射（转换）为Strings。为此，您只需将 传递Substring给Stringsinit函数即可：

let separated = requestResponse.characters.split(separator: " ").map(String.init)

Answer 4

如果是Swift 4，您可以这样使用：

let separated = requestResponse.split(separator: " ")
var photo = String(separated.first ?? "")

Answer 5

一种使用高阶函数分割字符串来获取字符串的方法：

let splitStringArray = requestResponse.split(separator: " ").map({ (substring) in
    return String(substring)
})