Different results of rangeOfComposedCharacterSequenceAtIndex in playground and in app

问题

rangeOfComposedCharacterSequenceAtIndex works differently in playground and in App, in playground mentioned below code returns as expected (location: 0, length: 4)

let flagRange = "🇳🇴".rangeOfComposedCharacterSequenceAtIndex(0)

But in application it returns (location: 0, length: 2)

来源：https://stackoverflow.com/questions/32831455/different-results-of-rangeofcomposedcharactersequenceatindex-in-playground-and-i