Swift string support

README.md

@@ -47,6 +47,9 @@ func apply(_ change: RangeMutation) -> NSRange?
 // creating
 init(_ textRange: NSTextRange, provider: NSTextElementProvider)
 init?(_ textRange: UITextRange, textView: UITextView)
+
+// working with Swift String
+func range(in string: String) -> Range<String.Index>?
 ```
 
 **NSTextRange**
@@ -76,6 +79,13 @@ func intersects(integersIn range: NSRange) -> Bool
 var limitSpanningRange: NSRange?
 ```
 
+**String**
+
+```Swift
+subscript(range: Range<Int>) -> Substring?
+subscript(range: NSRange) -> Substring?
+```
+
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Sources/Rearrange/String+NSRange.swift

@@ -0,0 +1,24 @@
+import Foundation
+
+public extension NSRange {
+    func range(in string: String) -> Range<String.Index>? {
+        return Range<String.Index>(self, in: string)
+    }
+}
+
+public extension String {
+    subscript(range: Range<Int>) -> Substring? {
+        get {
+            let start = index(startIndex, offsetBy: range.lowerBound)
+            let end = index(start, offsetBy: range.count)
+
+            return self[start..<end]
+        }
+    }
+
+    subscript(range: NSRange) -> Substring? {
+        get {
+            return range.range(in: self).flatMap({ self[$0] })
+        }
+    }
+}