Added insertString and deleteString

Sources/TextViewPlus/NSTextView+AttributedString.swift

@@ -35,6 +35,7 @@ public extension NSTextView {
         return attributedSubstring(forProposedRange: range, actualRange: actualRange)?.copy() as? NSAttributedString
     }
 
+    /// Undoable replacement of attributed string in specified range
     func replaceString(in range: NSRange, with attributedString: NSAttributedString) {
         if let manager = undoManager {
             let originalString = safeAttributedSubstring(forProposedRange: range, actualRange: nil)
@@ -50,4 +51,52 @@ public extension NSTextView {
 
         replaceCharacters(in: range, with: attributedString)
     }
+
+    func insertCharacters(_ attributedString: NSAttributedString, at location: Int) {
+        guard let storage = textStorage else {
+            fatalError("Unable to replace characters in a textview without a backing NSTextStorage")
+        }
+
+        storage.insert(attributedString, at: location)
+
+        didChangeText()
+    }
+
+    /// Undoable insertion of attributed string at specified location
+    func insertString(_ attributedString: NSAttributedString, at location: Int) {
+        if let manager = undoManager {
+            let inverseLength = attributedString.length
+            let inverseRange = NSRange(location: location, length: inverseLength)
+
+            manager.registerUndo(withTarget: self, handler: { view in
+                view.deleteString(in: inverseRange)
+            })
+        }
+
+        insertCharacters(attributedString, at: location)
+    }
+
+    func deleteCharacters(in range: NSRange) {
+        guard let storage = textStorage else {
+            fatalError("Unable to replace characters in a textview without a backing NSTextStorage")
+        }
+
+        storage.deleteCharacters(in: range)
+
+        didChangeText()
+    }
+
+    /// Undoable deletion of string in specified range
+    func deleteString(in range: NSRange) {
+        if let manager = undoManager {
+            let originalString = safeAttributedSubstring(forProposedRange: range, actualRange: nil)
+            let usableReplacementString = originalString ?? NSAttributedString()
+
+            manager.registerUndo(withTarget: self, handler: { view in
+                view.insertString(usableReplacementString, at: range.location)
+            })
+        }
+
+        deleteCharacters(in: range)
+    }
 }

Tests/TextViewPlusTests/TextViewPlusTests.swift

@@ -41,6 +41,44 @@ final class TextViewPlusTests: XCTestCase {
 
         XCTAssertEqual(textView.string, "abc")
     }
+
+    func testProgrammaticInsertionOfAttributedString() {
+        let textView = TestableTextView(string: "abc")
+
+        let attrString = NSAttributedString(string: "z")
+        textView.insertString(attrString, at: 1)
+
+        XCTAssertEqual(textView.string, "azbc")
+
+        textView.undoManager!.undo()
+
+        XCTAssertEqual(textView.string, "abc")
+    }
+
+    func testProgrammaticDeletionOfAttributedString() {
+        let textView = TestableTextView(string: "abc")
+
+        textView.deleteString(in: NSRange(location: 1, length: 1))
+
+        XCTAssertEqual(textView.string, "ac")
+
+        textView.undoManager!.undo()
+
+        XCTAssertEqual(textView.string, "abc")
+    }
+
+    func testProgrammaticDeletionOfAttributedStringWithFullRange() {
+        let textView = TestableTextView(string: "abc")
+
+        textView.deleteString(in: NSRange(location: 0, length: 3))
+
+        XCTAssert(textView.string.isEmpty)
+
+        textView.undoManager!.undo()
+
+        XCTAssertEqual(textView.string, "abc")
+    }
+
 }
 
 extension TextViewPlusTests {