Binary to hexadecimal in Swift

Question

I have a string in binary (for example "00100100"), and I want it in hexadecimal (like "24").

Is there a method written to convert Binary to Hexadecimal in Swift?

Answer 1

A possible solution:

func binToHex(bin : String) -> String {
    // binary to integer:
    let num = bin.withCString { strtoul($0, nil, 2) }
    // integer to hex:
    let hex = String(num, radix: 16, uppercase: true) // (or false)
    return hex
}

This works as long as the numbers fit into the range of UInt (32-bit or 64-bit, depending on the platform). It uses the BSD library function strtoul() which converts a string to an integer according to a given base.

For larger numbers you have to process the input in chunks. You might also add a validation of the input string.

Update for Swift 3/4: The strtoul function is no longer needed. Return nil for invalid input:

func binToHex(_ bin : String) -> String? {
    // binary to integer:
    guard let num = UInt64(bin, radix: 2) else { return nil }
    // integer to hex:
    let hex = String(num, radix: 16, uppercase: true) // (or false)
    return hex
}