I'm was trying to convert hexString to Array of Bytes([UInt8]) I searched everywhere but couldn't find a solution. Below is my swift 2 code
func stringToBytes(_ string: String) -> [UInt8]? {
let chars = Array(string)
let length = chars.count
if length & 1 != 0 {
return nil
}
var bytes = [UInt8]()
bytes.reserveCapacity(length/2)
for var i = 0; i < length; i += 2 {
if let a = find(hexChars, chars[i]),
let b = find(hexChars, chars[i+1]) {
bytes.append(UInt8(a << 4) + UInt8(b))
} else {
return nil
}
}
return bytes
}
Example Hex
Hex : "7661706f72"
expectedOutput : "vapor"
This code can generate the same output as your swift 2 code.
func stringToBytes(_ string: String) -> [UInt8]? {
let length = string.characters.count
if length & 1 != 0 {
return nil
}
var bytes = [UInt8]()
bytes.reserveCapacity(length/2)
var index = string.startIndex
for _ in 0..<length/2 {
let nextIndex = string.index(index, offsetBy: 2)
if let b = UInt8(string[index..<nextIndex], radix: 16) {
bytes.append(b)
} else {
return nil
}
index = nextIndex
}
return bytes
}
let bytes = stringToBytes("7661706f72")
print(String(bytes: bytes!, encoding: .utf8)) //->Optional("vapor")
Here is a sketch of how I'd do it in a more idiomatic Swift style (this might be Swift 4 only):
func toPairsOfChars(pairs: [String], string: String) -> [String] {
if string.count == 0 {
return pairs
}
var pairsMod = pairs
pairsMod.append(String(string.prefix(2)))
return toPairsOfChars(pairs: pairsMod, string: String(string.dropFirst(2)))
}
func stringToBytes(_ string: String) -> [UInt8]? {
// omit error checking: remove '0x', make sure even, valid chars
let pairs = toPairsOfChars(pairs: [], string: string)
return pairs.map { UInt8($0, radix: 16)! }
}
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