How to convert String to byte in Swift？
Like String .getBytes()in Java.
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possible duplicate of How to convert NSString to bytesahruss– ahruss2014-07-30 02:31:43 +00:00Commented Jul 30, 2014 at 2:31
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7 Answers
There is a more elegant way.
Swift 3:
let str = "Hello"
let buf = [UInt8](str.utf8)
Swift 4: (thanks to @PJ_Finnegan)
let str = "Hello"
let buf: [UInt8] = Array(str.utf8)
3 Comments
Albin Stigo
I don't know why I put in
var buf, might as well be let buf
JeremyP
Definitely the best way.
PJ_Finnegan
Apparently not working in Swift 4. Use
var buf : [UInt8] = Array(str.utf8) instead.You can iterate through the UTF8 code points and create an array:
var str = "hello, world"
var byteArray = [Byte]()
for char in str.utf8{
byteArray += [char]
}
println(byteArray)
3 Comments
xaxxon
[(Byte)] is not identical to to 'UInt8'
Joe Daniels
@xaxxon in what way is it not?
xaxxon
@JoeDaniels I have no clue. I'm not even sure I wrote that.
edit/update: Xcode 11.5 • Swift 5.2
extension StringProtocol {
var data: Data { .init(utf8) }
var bytes: [UInt8] { .init(utf8) }
}
"12345678".bytes // [49, 50, 51, 52, 53, 54, 55, 56]
Comments
String.withCString is the peer to Java's String.getBytes(void). Use it like this (extra typing added):
let s = "42"
s.withCString {
( bytes : (UnsafePointer<CChar>) ) -> Void in
let k = atoi(bytes)
println("k is \(k)")
}
Comments
Another option, for when you need to be able to pass to C-library functions:
let str = hexColour.cStringUsingEncoding(NSUTF8StringEncoding)
let x = strtol(str!, nil, 16)
Comments
string.utf8 or string.utf16 should do something like what you are asking for. See here for more info: https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/StringsAndCharacters.html.
Comments
Swift 4.1.
It depends what you want to achieve. For the same question, I used...
let message = "Happy"
for v in message.utf8 {
print(v)
}
I then performed the operations I needed on the individual byte. The output is:
//72
//97
//112
//112
//121
https://developer.apple.com/documentation/swift/string.utf8view
