如何从Swift 2中的字符串中删除特殊字符？

Question

如何从字符串中删除特殊字符的答案 ？ 不管用.

这是我得到的,它给了我一个错误

func removeSpecialCharsFromString(str: String) -> String {
    let chars: Set<String> = Set(arrayLiteral: "abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLKMNOPQRSTUVWXYZ1234567890+-*=(),.:!_")

    return String(str.characters.filter { chars.contains($0) }) //error here at $0
}

$ 0处的错误表示_Element(aka Character)无法转换为预期的参数类型'String'.

Answer 1

像这样:

func removeSpecialCharsFromString(text: String) -> String {
    let okayChars : Set<Character> = 
        Set("abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLKMNOPQRSTUVWXYZ1234567890+-*=(),.:!_".characters)
    return String(text.characters.filter {okayChars.contains($0) })
}

以下是测试方法:

let s = removeSpecialCharsFromString("père") // "pre"

Answer 2

SWIFT 4:

func removeSpecialCharsFromString(text: String) -> String {
    let okayChars = Set("abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLKMNOPQRSTUVWXYZ1234567890+-=().!_")
    return text.filter {okayChars.contains($0) }
}

更清洁的方式:

extension String {

    var stripped: String {
        let okayChars = Set("abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLKMNOPQRSTUVWXYZ1234567890+-=().!_")
        return self.filter {okayChars.contains($0) }
    }
}

使用此扩展名如:

let myCleanString = "some.Text@#$".stripped

输出:"some.Text"

Answer 3

我认为更清洁的解决方案可能是这种方法:

extension String {
    var alphanumeric: String {
        return self.components(separatedBy: CharacterSet.alphanumerics.inverted).joined().lowercased()
    }
}

Answer 4

尝试这个：

someString.removeAll(where: {$0.isPunctuation})

Answer 5

在Swift 1.2中,

let chars = Set("abcde...")

创建了一个包含给定字符串中所有字符的集合.在Swift 2.0中,必须这样做

let chars = Set("abcde...".characters)

原因是字符串本身不再符合 SequenceType,您必须characters明确使用视图.

通过该更改,您的方法可以按预期编译和工作:

func removeSpecialCharsFromString(str: String) -> String {
    let chars = Set("abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLKMNOPQRSTUVWXYZ1234567890+-*=(),.:!_".characters)
    return String(str.characters.filter { chars.contains($0) })
}

let cleaned = removeSpecialCharsFromString("ab€xy")
print(cleaned) // abxy

备注: @Kametrixom建议只创建一次.因此,如果上述方法存在性能问题,您可以将该集的声明移到函数外部,或者将其设置为本地static:

func removeSpecialCharsFromString(str: String) -> String {
    struct Constants {
        static let validChars = Set("abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLKMNOPQRSTUVWXYZ1234567890+-*=(),.:!_".characters)
    }
    return String(str.characters.filter { Constants.validChars.contains($0) })
}