Swift 3 method to create utf8 encoded Data from String
Swift 3 method to create utf8 encoded Data from String
I know there's a bunch of pre Swift3 questions regarding NSData stuff. I'm curious how to go between a Swift3 String to a utf8 encoded (with or without null termination) to Swift3 Data object.
String
Data
The best I've come up with so far is:
let input = "Hello World"
let terminatedData = Data(bytes: Array(input.nulTerminatedUTF8))
let unterminatedData = Data(bytes: Array(input.utf8))
Having to do the intermediate Array() construction seems wrong.
Array()
2 Answers
2
It's simple:
let input = "Hello World"
let data = input.data(using: .utf8)!
If you want to terminate data with null, simply append a 0 to it. Or you may call cString(using:)
data
append
cString(using:)
let cString = input.cString(using: .utf8)! // null-terminated
That's perfect, thanks. Amusingly, the
cString method returns a [UInt8]– Travis Griggs
Jun 17 '16 at 23:03
cString
[UInt8]
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– Matthew Seaman
Jun 20 '16 at 2:19
NSString methods from NSFoundation framework should be dropped in favor for Swift Standard Library equivalents. Data can be initialized with any Sequence which elements are UInt8. String.UTF8View satisfies this requirement.
NSString
NSFoundation
Sequence
UInt8
String.UTF8View
let input = "Hello World"
let data = Data(input.utf8)
// [72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100]
String null termination is an implementation detail of C language and it should not leak outside. If you are planning to work with C APIs, please take a look at the utf8CString property of String type:
utf8CString
String
public var utf8CString: ContiguousArray<CChar> get
Data can be obtained after CChar is converted to UInt8:
Data
CChar
UInt8
let input = "Hello World"
let data = Data(input.utf8CString.map UInt8($0) )
// [72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100, 0]
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Would you agree that this question should be reviewed again as accepted answer uses NSFoundation API instead of Swift one?
– Wojciech Nagrodzki
Aug 25 at 9:51