How to convert array of bytes [UInt8] into hexa string in Swift - swift

Question

I found how to convert hexa string into bytes [UInt8] but I have not found how to convert bytes [UInt8] into an hexa string in Swift
this hexstring convert to string code:
static func bytesConvertToHexstring(byte : [UInt8]) -> String {
var string = ""
for val in byte {
//getBytes(&byte, range: NSMakeRange(i, 1))
string = string + String(format: "%02X", val)
}
return string
}
samething like this result:
"F063C52A6FF7C8904D3F6E379EB85714ECA9C1CB1E8DFD6CA5D3B4A991269D60F607C565C327BD0ECC0985F74E5007E0D276499E1ADB4E0C92D8BDBB46E57705B2D5390FF5CBD4ED1B850C537301CA7E"
UInt8 array: [0, 11, 8, 15, 6, 6, 5, 8, 8, 4, 14, 14, 0, 0, 9, 12, 6, 4, 10, 6, 4, 8, 6, 2, 14, 2, 6, 13, 3, 3, 12, 4, 3, 12, 8, 13, 14, 4, 10, 1, 12, 15, 4, 0, 14, 14, 0, 8, 8, 14, 6, 15, 2, 2, 9, 15, 13, 6, 2, 6, 8, 15, 4, 2, 12, 1, 0, 13, 13, 4, 6, 0, 9, 6, 8, 2, 7, 0, 6, 1, 3, 3, 9, 15, 5, 7, 12, 8, 7, 5, 13, 14, 15, 6, 7, 6, 12, 6, 7, 7, 11, 9, 6, 0, 14, 5, 6, 14, 1, 5, 13, 10, 12, 13, 14, 2, 13, 14, 4, 7, 13, 0, 3, 10, 6, 11, 9, 12, 7, 11, 5, 3, 5, 11, 4, 9, 6, 10, 14, 0, 11, 7, 15, 9, 3, 14, 5, 1, 10, 14, 5, 6, 12, 4, 12, 14, 4, 3, 9, 8, 0]

Answer 1

Xcode 11 • Swift 5.1 or later
extension StringProtocol {
var hexa: [UInt8] {
var startIndex = self.startIndex
return (0..<count/2).compactMap { _ in
let endIndex = index(after: startIndex)
defer { startIndex = index(after: endIndex) }
return UInt8(self[startIndex...endIndex], radix: 16)
}
}
}
extension DataProtocol {
var data: Data { .init(self) }
var hexa: String { map { .init(format: "%02x", $0) }.joined() }
}
"0f00ff".hexa // [15, 0, 255]
"0f00ff".hexa.data // 3 bytes
"0f00ff".hexa.data.hexa // "0f00ff"
"0f00ff".hexa.data as NSData // <0f00ff>
Note: Swift 4 or 5 syntax click here

Answer 2

Thanks to Brian for his routine. It could conveniently be added as a Swift extension as below.
extension Array where Element == UInt8 {
func bytesToHex(spacing: String) -> String {
var hexString: String = ""
var count = self.count
for byte in self
{
hexString.append(String(format:"%02X", byte))
count = count - 1
if count > 0
{
hexString.append(spacing)
}
}
return hexString
}
}
Example of call:
let testData: [UInt8] = [15, 0, 255]
print(testData.bytesToHex(spacing: " ")) // 0F 00 FF

Answer 3

One liner:
testData.map{ String(format:"%02X", $0) }.joined(separator: " ")

Answer 4

XCode 12-beta 6.
I know its late but I use this simple routine that gives an arbitrary spacing. I converted it from Java on Android. I also have C and other language versions of this - it easy to go from language to language when you cant remember all the language-specific libraries.
public static func bytesToHex(bytes: [UInt8], spacing: String) -> String
{
var hexString: String = ""
var count = bytes.count
for byte in bytes
{
hexString.append(String(format:"%02X", byte))
count = count - 1
if count > 0
{
hexString.append(spacing)
}
}
return hexString
}
It creates a two-digit hex string with an arbitrary spacing string between elements. I use it like this, for example, to display the results of a characteristic read
let charValue = [UInt8](characteristic.value ?? Data())
print("Characteristic \(characteristic.uuid) read with value: \(Btle.bytesToHex(bytes: charValue, spacing: " "))")
with an output that looks like this:
Characteristic System ID read with value: 00 1C 05 FF FE FF E8 74
My experience with Swift and iOS is very limited; perhaps the seasoned Swift people can 'Swiftify' it.