What's the simplest way to convert from a single character String to an ASCII value in Swift?

Question

I just want to get the ASCII value of a single char string in Swift. This is how I\'m currently doing it:

var singleChar = \"a\"
println(singleChar.unicodeSc         


        

Answer 1

var singchar = "a" as NSString

print(singchar.character(at: 0))

Swift 3.1

Answer 2

UnicodeScalar("1")!.value // returns 49

Swift 3.1

Answer 3

Now in Xcode 7.1 and Swift 2.1

var singleChar = "a"

singleChar.unicodeScalars.first?.value

Answer 4

Here's my implementation, it returns an array of the ASCII values.

extension String {

    func asciiValueOfString() -> [UInt32] {

      var retVal = [UInt32]()
      for val in self.unicodeScalars where val.isASCII() {
          retVal.append(UInt32(val))
      }
      return retVal
    }
}

Note: Yes it's Swift 2 compatible.

Answer 5

With Swift 5, you can pick one of the following approaches in order to get the ASCII numeric representation of a character.

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#1. Using Character's asciiValue property

Character has a property called asciiValue. asciiValue has the following declaration:

var asciiValue: UInt8? { get }

The ASCII encoding value of this character, if it is an ASCII character.

The following Playground sample codes show how to use asciiValue in order to get the ASCII encoding value of a character:

let character: Character = "a"
print(character.asciiValue) //prints: Optional(97)

let string = "a"
print(string.first?.asciiValue) //prints: Optional(97)

let character: Character = "                                                                    

                                                        
            

Answer 6

A slightly shorter way of doing this could be:

first(singleChar.unicodeScalars)!.value

As with the subscript version, this will crash if your string is actually empty, so if you’re not 100% sure, use the optional:

if let ascii = first(singleChar.unicodeScalars)?.value {

}

Or, if you want to be extra-paranoid,

if let char = first(singleChar.unicodeScalars) where char.isASCII() {
    let ascii = char.value
}