NSData to [Uint8] in Swift - swift

Question

I couldn't find a solution to this problem in Swift (all of them are Objective-C, and they deal with pointers which I don't think exist in Swift in the same form). Is there any way to convert a NSData object into an array of bytes in the form of [Uint8] in Swift?

Answer 1

You can avoid first initialising the array to placeholder values, if you go through pointers in a slightly convoluted manner, or via the new Array constructor introduced in Swift 3:
Swift 3
let data = "foo".data(using: .utf8)!
// new constructor:
let array = [UInt8](data)
// …or old style through pointers:
let array = data.withUnsafeBytes {
[UInt8](UnsafeBufferPointer(start: $0, count: data.count))
}
Swift 2
Array(UnsafeBufferPointer(start: UnsafePointer<UInt8>(data.bytes), count: data.length))

Answer 2

Swift 5 Solution
Data to [bytes]
extension Data {
var bytes: [UInt8] {
return [UInt8](self)
}
}
[bytes] to Data
extension Array where Element == UInt8 {
var data: Data {
return Data(self)
}
}

Answer 3

It's funny but exist more simple solution. Works in Swift 3. Surely. I've used this today.
data: Data // as function parameter
let byteArray = [UInt8](data)
That's all! :)
NSData easily bridged to Data.
UPDATE: (due to Andrew Koster comment)
Swift 4.1, Xcode 9.3.1
Just has been rechecked - all works as expected.
if let nsData = NSData(base64Encoded: "VGVzdFN0cmluZw==", options: .ignoreUnknownCharacters) {
let bytes = [UInt8](nsData as Data)
print(bytes, String(bytes: bytes, encoding: .utf8))
Output: [84, 101, 115, 116, 83, 116, 114, 105, 110, 103] Optional("TestString")

Answer 4

You can use the getBytes function of NSData to get the byte array equivalent.
As you did not provide any source code, I will use a Swift String contents that has been converted to NSData.
var string = "Hello World"
let data : NSData! = string.dataUsingEncoding(NSUTF8StringEncoding)
let count = data.length / sizeof(UInt8)
// create an array of Uint8
var array = [UInt8](count: count, repeatedValue: 0)
// copy bytes into array
data.getBytes(&array, length:count * sizeof(UInt8))
println(array)
Swift 3/4
let count = data.length / MemoryLayout<UInt8>.size
// create an array of Uint8
var byteArray = [UInt8](repeating: 0, count: count)
// copy bytes into array
data.getBytes(&byteArray, length:count)

Answer 5

Swift 3/4
let data = Data(bytes: [0x01, 0x02, 0x03])
let byteArray: [UInt8] = data.map { $0 }

Answer 6

You can try
extension Data {
func toByteArray() -> [UInt8]? {
var byteData = [UInt8](repeating:0, count: self.count)
self.copyBytes(to: &byteData, count: self.count)
return byteData
}
}

Answer 7

swift 4 and image data to a byte array.
func getArrayOfBytesFromImage(imageData:Data) ->[UInt8]{
let count = imageData.count / MemoryLayout<UInt8>.size
var byteArray = [UInt8](repeating: 0, count: count)
imageData.copyBytes(to: &byteArray, count:count)
return byteArray
}