Swift converting signed array of Int [int8] to unsigned array of Int [UInt8]

Question

How to convert signed array of [Int8] to unsigned array of [UInt8].

 let arryData: [Int8] =  [-108, 11, -107, -14, 35, -57, -116, 118, 54, 91, 12, 67, 21, 29, -44, 111]

I just want to convert this above into array of Unsigned [UInt8]. How to achieve this in swift.? Thanks in advance.

Answer 1

If your intention is to convert signed 8-bit integers to unsigned ones with the same bit representation (e.g. -1 -> 255):

let intArray: [Int8] =  [0, 1, 2, 127, -1, -2, -128]
let uintArray = intArray.map { UInt8(bitPattern: $0) }

print(uintArray)
// [0, 1, 2, 127, 255, 254, 128]

Answer 2

[Int8] -> [UInt8]

You haven't specified how you want to treat negative values; by flipping them to their positive counterpart or by removing them. Below follows both cases.

---

Transforming negative values to positive ones by flipping sign:

let arrayData: [Int8] =  [-108, 11, -107, -14, 35, -57, -116, 118, 54, 91, 12, 67, 21, 29, -44, 111]
let arrayDataUnsigned = arrayData.map { UInt8(abs($0)) }
    /* [108, 11, 107, 14, 35, 57, 116, 118, 54, 91, 
        12, 67, 21, 29, 44, 111] */

Or, by removing the negative values:

let arrayDataUnsigned = arrayData.flatMap { $0 < 0 ? nil : UInt8($0) }
    /* [11, 35, 118, 54, 91, 12, 67, 21, 29, 111] */