Swift 2.0 substringwithrange

我有 Xcode 7 gm,swift 2.0是什么等效的表达式：

Let myNsstring = "full text container"
myNsstring.substringWithRange(NSRange(location: 0,length: 3))

有了新的字符串类吗？

试试这个：

let myString = "full text container"
myString[myString.startIndex..<myString.startIndex.advancedBy(3)]