Swift Strings: Unicode & Scalars

Swift Strings: Unicode & Scalars

Swift strings are Unicode-correct.

A single character can be composed of multiple Unicode scalars.

Visually identical strings can compare equal.

Composed Characters

Some characters are made from multiple Unicode scalars; Swift treats them as a single character for comparison and length.

let e1 = "é"
let e2 = "e\u{301}"   // e + COMBINING ACUTE ACCENT
print(e1 == e2)
print(e2)

This example shows that a precomposed character and a composed sequence are considered equal in Swift.

Unicode Scalars

Inspect the underlying Unicode scalar values with the unicodeScalars view.

The unicodeScalars view yields values of type UnicodeScalar.

let s = "e\u{301}"
for scalar in s.unicodeScalars {
  print(scalar.value)   // 101, 769
}

This example prints the Unicode scalar code points that make up the character.