這種比較曾在斯威夫特2,但不會再在斯威夫特3:如何比較Range <String.Index>和DefaultBidirectionalIndices <String.CharacterView>?
let myStringContainsOnlyOneCharacter = mySting.rangeOfComposedCharacterSequence(at: myString.startIndex) == mySting.characters.indices
如何比較範圍和DefaultBidirectionalIndices?
看一看一個t http://stackoverflow.com/a/39104563/1187415,其中包含Swift 2和Swift 3的'isSingleComposedCharacter'定義。 –