isLowSurrogate

Returns true if this character is a Unicode low-surrogate code unit (also known as trailing-surrogate code unit).

expect fun Char.isLowSurrogate(): Boolean(source)

fun main() {
    val highSurrogate = '\uD834'
    val lowSurrogate = '\uDD1E'

    println(highSurrogate.isLowSurrogate()) // false
    println(lowSurrogate.isLowSurrogate())  // true
}

Source