Question

我在swift中有一系列角色：

static let charArray: [Character] = [ "S", "t", "r", "i", "n", "g"]

我想对每个Character做一些逐位运算作为一个字节（UInt8）。例如，如何将charArray[0]转换为UInt8？

Answer 1

您需要通过String：s的Character代表转换为UInt8。但是，您无需在[Character] -> [UInt8]转换中显式初始化数组;由于String.UTF8View（来自String.utf8）是CollectionType，因此您可以对map本身应用String.UTF8View操作;初始化为UInt8。即，

let charArray: [Character] = [ "S", "t", "r", "i", "n", "g"]
let asUInt8Array = String(charArray).utf8.map{ UInt8($0) }

print(asUInt8Array)
/* [83, 116, 114, 105, 110, 103] */

print(asUInt8Array.dynamicType)
/* Array<UInt8> */

关于你在下面的评论（“对于Swift的抽象感到沮丧，与Objective-C的简单方式相比”）：如果你认为上述内容很混乱，你可以包括它在SequenceType的扩展中限制为Character元素，允许在实践中更容易使用。 E.g：

extension SequenceType where Generator.Element == Character {

    /* extension accessible as function */
    func asByteArray() -> [UInt8] {
        return String(self).utf8.map{UInt8($0)}
    }

    /* or, as @LeoDabus pointed out below (thanks!),
       use a computed property for this simple case  */
    var byteArray : [UInt8] {
        return String(self).utf8.map{UInt8($0)}
    }
}

用法示例：

let charArray: [Character] = [ "S", "t", "r", "i", "n", "g"]

/* use extension function */
let asUInt8Array = charArray.asByteArray()

/* or computed property */
let asUInt8Array = charArray.byteArray

Answer 2

我不确定如何将字符转换为UTF-8，但字符串具有utf8属性，因此您可以使用以下内容：

let charArray: [Character] = [ "S", "t", "r", "i", "n", "g"]
let string = Array(String(charArray).utf8)
print(string)

Answer 3

这就是我最终做到的方式：

var char: Character = "a"
var byte: UInt8 = Array(String(char).utf8)[0]

必须有更好的方法......

Answer 4

改善@dfri回答https://stackoverflow.com/a/36025104/1979882

Swift 3 你必须使用它：

extension Sequence where Iterator.Element == Character {

    /* extension accessible as function */
    func asByteArray() -> [UInt8] {
        return String(self).utf8.map{UInt8($0)}
    }

    /* or, as @LeoDabus pointed out below (thanks!),
     use a computed property for this simple case  */
    var byteArray : [UInt8] {
        return String(self).utf8.map{UInt8($0)}
    }
}

如何在Swift中将Character转换为UInt8

4 个答案: