How to convert HexString into ByteArray in Swift 3

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. . let nextIndex = string.index(index, offsetBy: 2)
 if let b = UInt8(string[index.. bytes.append(b)
} else {
 return nil
 }
 index = nextIndex
 }
 return bytes
}

let bytes = stringToBytes("7661706f72")
print(String(bytes: bytes!, encoding: .utf8)) //->Optional("vapor")

I’m trying to convert hexString to byte array ([UInt8]) I searched everywhere but couldn’t find a solution. Below is my quick 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  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

Hexadecimal: “7661706f72”

ExpectedOutput: “Steam”

This code can be generated with swift 2 The same output as the code.

func stringToBytes(_ string: String) -> [UInt8]? {
 let length = string.characters.count< br /> if length & 1 != 0 {
 return nil
 }
 var bytes = [UInt8]()
 bytes.reserveCapacity(length/2)
 var index = string.startIndex
 for _ in 0.. let nextIndex = string.index(index, offsetBy: 2)
 if let b = UInt8(string[ index.. bytes.append(b)
} else {
 return nil
 }
 index = nextIndex
 }
 return bytes
}

let bytes = stringToBytes("7661706f72")
print(String(bytes: bytes!, encoding: .utf8)) //->Optional("vapor")