transcode(_:from:to:stoppingOnError:into:)

Declaration

func transcode<Input, InputEncoding, OutputEncoding>(_ input: Input, from inputEncoding: InputEncoding.Type, to outputEncoding: OutputEncoding.Type, stoppingOnError stopOnError: Bool, into processCodeUnit: (OutputEncoding.CodeUnit) -> Void) -> Bool where Input : IteratorProtocol, InputEncoding : _UnicodeEncoding, OutputEncoding : _UnicodeEncoding, Input.Element == InputEncoding.CodeUnit

Parameters

• input:

  An iterator of code units to be translated, encoded as inputEncoding. If stopOnError is false, the entire iterator will be exhausted. Otherwise, iteration will stop if an encoding error is detected.

• inputEncoding:

  The Unicode encoding of input.

• outputEncoding:

  The destination Unicode encoding.

• stopOnError:

  Pass true to stop translation when an encoding error is detected in input. Otherwise, a Unicode replacement character ("\u{FFFD}") is inserted for each detected error.

• processCodeUnit:

  A closure that processes one outputEncoding code unit at a time.

Return Value

true if the translation detected encoding errors in input; otherwise, false.

Discussion

The following example transcodes the UTF-8 representation of the string "Fermata 𝄐" into UTF-32.

let fermata = "Fermata 𝄐"
let bytes = fermata.utf8
print(Array(bytes))
// Prints "[70, 101, 114, 109, 97, 116, 97, 32, 240, 157, 132, 144]"

var codeUnits: [UTF32.CodeUnit] = []
let sink = { codeUnits.append($0) }
transcode(bytes.makeIterator(), from: UTF8.self, to: UTF32.self,
          stoppingOnError: false, into: sink)
print(codeUnits)
// Prints "[70, 101, 114, 109, 97, 116, 97, 32, 119056]"

The sink closure is called with each resulting UTF-32 code unit as the function iterates over its input.