import Foundation
var str: String = "0123456789"
let start = str.index(str.startIndex,offsetBy: 3);
let str1 = str.substring(from: start)
print(str1) //3456789
let end = str.index(str.endindex,offsetBy: -3)
let str2 = str.substring(to: end)
print(str2) //0123456
let range = Range<String.Index>(uncheckedBounds: (lower: start,upper: end))
let str3 = str.substring(with: range)
print(str3) //3456
extension String {
subscript(r: Range<Int>) -> String {
get {
let startIndex = self.index(self.startIndex,offsetBy: r.lowerBound);
let endindex = self.index(self.startIndex,offsetBy: r.upperBound)
return self.substring(with: Range(startIndex..<endindex))
}
set {
let startIndex = self.index(self.startIndex,offsetBy: r.upperBound)
self.replaceSubrange(Range(startIndex..<endindex),with: newValue)
}
}
}
let i = 3
let j = 7
print(str[i..<j]) //3456
str[1..<3] = "aaa"
print(str) //0aaa3456789