Fix NSRange length calculations using String.count instead of UTF-16 count

.swiftlint.yml

@@ -119,3 +119,9 @@ custom_rules:
     message: "Using `LocalizedStringKey` is incompatible with our tooling and doesn't allow you to provide a hint/context comment for translators either. Please use `NSLocalizedString` instead, even with SwiftUI code."
     severity: error
     excluded: '.*Widgets/.*'
+
+  full_range_attributed_string_attribute:
+    name: "Full-Range Attributed String Attribute"
+    regex: '\.addAttributes?\([^\n]*range:\s*NS(MakeRange\(0,|Range\(location:\s*0,\s*length:)'
+    message: "Use `applyAttribute(_:value:)` or `applyAttributes(_:)` instead of manually constructing a full-range NSRange. Manual ranges are error-prone with emoji and other multi-code-unit characters."
+    severity: warning

Modules/Sources/FormattableContentKit/Ranges/FormattableNoticonRange.swift

@@ -21,10 +21,10 @@ public class FormattableNoticonRange: FormattableContentRange {
         let shiftedRange = rangeShifted(by: shift)
         insertIcon(to: string, at: shiftedRange)
 
-        let longerRange = NSMakeRange(shiftedRange.location, shiftedRange.length + noticon.count)
+        let longerRange = NSMakeRange(shiftedRange.location, shiftedRange.length + noticon.utf16.count)
         apply(styles, to: string, at: longerRange)
 
-        return noticon.count
+        return noticon.utf16.count
     }
 
     func insertIcon(to string: NSMutableAttributedString, at shiftedRange: NSRange) {

Modules/Sources/WordPressKit/NonceRetrieval.swift

@@ -48,7 +48,7 @@ enum NonceRetrievalMethod {
 
     private func scrapNonceFromNewPost(html: String) -> String? {
         guard let regex = try? NSRegularExpression(pattern: "apiFetch.createNonceMiddleware\\(\\s*['\"](?<nonce>\\w+)['\"]\\s*\\)", options: []),
-            let match = regex.firstMatch(in: html, options: [], range: NSRange(location: 0, length: html.count)) else {
+            let match = regex.firstMatch(in: html, options: [], range: NSRange(location: 0, length: html.utf16.count)) else {
                 return nil
         }
         let nsrange = match.range(withName: "nonce")

Modules/Sources/WordPressKit/WordPressOrgXMLRPCValidator.swift

@@ -317,7 +317,7 @@ open class WordPressOrgXMLRPCValidator: NSObject {
 
         let matches = rsdURLRegExp.matches(in: html,
                                                    options: NSRegularExpression.MatchingOptions(),
-                                                   range: NSRange(location: 0, length: html.count))
+                                                   range: NSRange(location: 0, length: html.utf16.count))
         if matches.count <= 0 {
             return nil
         }

Modules/Sources/WordPressShared/Utility/RichContentFormatter.swift

@@ -77,17 +77,17 @@ import WordPressSharedObjC
 
         content = RegEx.styleTags.stringByReplacingMatches(in: content,
                                                            options: .reportCompletion,
-                                                           range: NSRange(location: 0, length: content.count),
+                                                           range: NSRange(location: 0, length: content.utf16.count),
                                                            withTemplate: "")
 
         content = RegEx.scriptTags.stringByReplacingMatches(in: content,
                                                             options: .reportCompletion,
-                                                            range: NSRange(location: 0, length: content.count),
+                                                            range: NSRange(location: 0, length: content.utf16.count),
                                                             withTemplate: "")
 
         content = RegEx.gutenbergComments.stringByReplacingMatches(in: content,
                                                                    options: .reportCompletion,
-                                                                   range: NSRange(location: 0, length: content.count),
+                                                                   range: NSRange(location: 0, length: content.utf16.count),
                                                                    withTemplate: "")
 
         return content
@@ -111,23 +111,23 @@ import WordPressSharedObjC
         // Convert div tags to p tags
         content = RegEx.divTagsStart.stringByReplacingMatches(in: content,
                                                               options: .reportCompletion,
-                                                              range: NSRange(location: 0, length: content.count),
+                                                              range: NSRange(location: 0, length: content.utf16.count),
                                                               withTemplate: openPTag)
 
         content = RegEx.divTagsEnd.stringByReplacingMatches(in: content,
                                                             options: .reportCompletion,
-                                                            range: NSRange(location: 0, length: content.count),
+                                                            range: NSRange(location: 0, length: content.utf16.count),
                                                             withTemplate: closePTag)
 
         // Remove duplicate/redundant p tags.
         content = RegEx.pTagsStart.stringByReplacingMatches(in: content,
                                                             options: .reportCompletion,
-                                                            range: NSRange(location: 0, length: content.count),
+                                                            range: NSRange(location: 0, length: content.utf16.count),
                                                             withTemplate: openPTag)
 
         content = RegEx.pTagsEnd.stringByReplacingMatches(in: content,
                                                           options: .reportCompletion,
-                                                          range: NSRange(location: 0, length: content.count),
+                                                          range: NSRange(location: 0, length: content.utf16.count),
                                                           withTemplate: closePTag)
 
         content = filterNewLines(content)
@@ -141,11 +141,11 @@ import WordPressSharedObjC
         var ranges = [NSRange]()
         // We don't want to remove new lines from preformatted tag blocks,
         // so get the ranges of such blocks.
-        let matches = RegEx.preTags.matches(in: content, options: .reportCompletion, range: NSRange(location: 0, length: content.count))
+        let matches = RegEx.preTags.matches(in: content, options: .reportCompletion, range: NSRange(location: 0, length: content.utf16.count))
         if matches.count == 0 {
 
             // No blocks found, so we'll parse the whole string.
-            ranges.append(NSRange(location: 0, length: content.count))
+            ranges.append(NSRange(location: 0, length: content.utf16.count))
 
         } else {
 
@@ -161,7 +161,7 @@ import WordPressSharedObjC
                 location = match.range.location + match.range.length
             }
 
-            length = content.count - location
+            length = content.utf16.count - location
             ranges.append(NSRange(location: location, length: length))
         }
 
@@ -191,7 +191,7 @@ import WordPressSharedObjC
 
         content = RegEx.styleAttr.stringByReplacingMatches(in: content,
                                                            options: .reportCompletion,
-                                                           range: NSRange(location: 0, length: content.count),
+                                                           range: NSRange(location: 0, length: content.utf16.count),
                                                            withTemplate: "")
 
         return content
@@ -242,7 +242,7 @@ import WordPressSharedObjC
             mImageStr.replaceOccurrences(of: srcImgURLStr,
                                          with: modifiedURL.absoluteString,
                                          options: .literal,
-                                         range: NSRange(location: 0, length: imgElementStr.count))
+                                         range: NSRange(location: 0, length: imgElementStr.utf16.count))
 
             mContent.replaceCharacters(in: match.range, with: mImageStr as String)
         }
@@ -287,10 +287,9 @@ import WordPressSharedObjC
         }
 
         var content = string.trim()
-        let matches = RegEx.trailingBRTags.matches(in: content, options: .reportCompletion, range: NSRange(location: 0, length: content.count))
-        if let match = matches.first {
-            let index = content.index(content.startIndex, offsetBy: match.range.location)
-            content = String(content.prefix(upTo: index))
+        let matches = RegEx.trailingBRTags.matches(in: content, options: .reportCompletion, range: NSRange(location: 0, length: content.utf16.count))
+        if let match = matches.first, let range = Range(match.range, in: content) {
+            content = String(content[content.startIndex..<range.lowerBound])
         }
 
         return content

Modules/Sources/WordPressShared/Utility/String+RangeConveresion.swift

@@ -48,10 +48,10 @@ extension String {
     /// - Returns: the requested `Range<String.Index>`
     ///
     func range(from nsRange: NSRange) -> Range<String.Index> {
-        let lowerBound = index(startIndex, offsetBy: nsRange.location)
-        let upperBound = index(lowerBound, offsetBy: nsRange.length)
-
-        return lowerBound ..< upperBound
+        guard let range = Range(nsRange, in: self) else {
+            preconditionFailure("Invalid NSRange \(nsRange) for string of UTF-16 length \(utf16.count)")
+        }
+        return range
     }
 
     func range(fromUTF16NSRange utf16NSRange: NSRange) -> Range<String.Index> {
@@ -160,11 +160,7 @@ extension String {
     /// - Returns: the requested `NSRange`.
     ///
     func nsRange(from range: Range<String.Index>) -> NSRange {
-
-        let location = distance(from: startIndex, to: range.lowerBound)
-        let length = distance(from: range.lowerBound, to: range.upperBound)
-
-        return NSRange(location: location, length: length)
+        NSRange(range, in: self)
     }
 
     /// Converts a `Range<String.Index>` into an UTF16 NSRange.
@@ -190,7 +186,7 @@ extension String {
     /// Returns a NSRange with a starting location at the very end of the string
     ///
     func endOfStringNSRange() -> NSRange {
-        return NSRange(location: count, length: 0)
+        return NSRange(location: utf16.count, length: 0)
     }
 
     func indexFromLocation(_ location: Int) -> String.Index? {

Modules/Sources/WordPressShared/Utility/String+RegEx.swift

@@ -16,7 +16,7 @@ extension String {
     public func replacingMatches(of regex: String, options: NSRegularExpression.Options = [], using block: (String, [String]) -> String) -> String {
 
         let regex = try! NSRegularExpression(pattern: regex, options: options)
-        let fullRange = NSRange(location: 0, length: count)
+        let fullRange = NSRange(location: 0, length: utf16.count)
         let matches = regex.matches(in: self, options: [], range: fullRange)
         var newString = self
 
@@ -49,7 +49,7 @@ extension String {
     ///
     public func matches(regex: String, options: NSRegularExpression.Options = []) -> [NSTextCheckingResult] {
         let regex = try! NSRegularExpression(pattern: regex, options: options)
-        let fullRange = NSRange(location: 0, length: count)
+        let fullRange = NSRange(location: 0, length: utf16.count)
 
         return regex.matches(in: self, options: [], range: fullRange)
     }
@@ -66,7 +66,7 @@ extension String {
     public func replacingMatches(of regex: String, with template: String, options: NSRegularExpression.Options = []) -> String {
 
         let regex = try! NSRegularExpression(pattern: regex, options: options)
-        let fullRange = NSRange(location: 0, length: count)
+        let fullRange = NSRange(location: 0, length: utf16.count)
 
         return regex.stringByReplacingMatches(in: self,
                                               options: [],

Modules/Sources/WordPressUI/Extensions/NSMutableAttributedString+Helpers.swift

@@ -5,10 +5,31 @@ import UIKit
 //
 extension NSMutableAttributedString {
 
+    /// Applies a single attribute to the entire string.
+    ///
+    /// Prefer this over manually constructing an `NSRange` with `NSMakeRange(0, …)`,
+    /// which is error-prone when mixing `String.count` (grapheme clusters) with
+    /// `NSRange` (UTF-16 code units).
+    ///
+    public func applyAttribute(_ key: NSAttributedString.Key, value: Any) {
+        // swiftlint:disable:next full_range_attributed_string_attribute
+        addAttribute(key, value: value, range: NSRange(location: 0, length: length))
+    }
+
+    /// Applies a collection of attributes to the entire string.
+    ///
+    /// Prefer this over manually constructing an `NSRange` with `NSMakeRange(0, …)`,
+    /// which is error-prone when mixing `String.count` (grapheme clusters) with
+    /// `NSRange` (UTF-16 code units).
+    ///
+    public func applyAttributes(_ attrs: [NSAttributedString.Key: Any]) {
+        // swiftlint:disable:next full_range_attributed_string_attribute
+        addAttributes(attrs, range: NSRange(location: 0, length: length))
+    }
+
     /// Applies the specified foreground color to the full length of the receiver.
     ///
     public func applyForegroundColor(_ color: UIColor) {
-        let range = NSRange(location: 0, length: length)
-        addAttribute(.foregroundColor, value: color, range: range)
+        applyAttribute(.foregroundColor, value: color)
     }
 }

Modules/Tests/WordPressSharedTests/RichContentFormatterTests.swift

@@ -56,6 +56,48 @@ class RichContentFormatterTests: XCTestCase {
         XCTAssertTrue(range.location != NSNotFound)
     }
 
+    // MARK: - Emoji / Multi-byte Character Tests
+    //
+    // These tests verify that string operations work correctly with emoji
+    // and other characters where String.count (grapheme clusters) differs
+    // from String.utf16.count (UTF-16 code units used by NSRange).
+    // The family emoji 👨‍👩‍👧‍👦 is 1 grapheme cluster but 11 UTF-16 code units.
+
+    func testRemoveForbiddenTagsWithEmoji() {
+        let input = "<p>Hello 👨‍👩‍👧‍👦👨‍👩‍👧‍👦 World</p><script>evil</script>"
+        let expected = "<p>Hello 👨‍👩‍👧‍👦👨‍👩‍👧‍👦 World</p>"
+        let result = RichContentFormatter.removeForbiddenTags(input)
+        XCTAssertEqual(result, expected, "Script tags after emoji should be removed")
+    }
+
+    func testRemoveInlineStylesWithEmoji() {
+        let input = "<p>Hello 👨‍👩‍👧‍👦👨‍👩‍👧‍👦</p><p style=\"color:red;\">test</p>"
+        let expected = "<p>Hello 👨‍👩‍👧‍👦👨‍👩‍👧‍👦</p><p>test</p>"
+        let result = RichContentFormatter.removeInlineStyles(input)
+        XCTAssertEqual(result, expected, "Inline styles after emoji should be removed")
+    }
+
+    func testNormalizeParagraphsWithEmoji() {
+        let input = "<div>Hello 👨‍👩‍👧‍👦👨‍👩‍👧‍👦</div><div>test</div>"
+        let expected = "<p>Hello 👨‍👩‍👧‍👦👨‍👩‍👧‍👦</p><p>test</p>"
+        let result = RichContentFormatter.normalizeParagraphs(input)
+        XCTAssertEqual(result, expected, "Div-to-p conversion after emoji should work")
+    }
+
+    func testFilterNewLinesWithEmoji() {
+        let input = "<p>Hello 👨‍👩‍👧‍👦👨‍👩‍👧‍👦</p>\n<p>World</p>\n"
+        let expected = "<p>Hello 👨‍👩‍👧‍👦👨‍👩‍👧‍👦</p><p>World</p>"
+        let result = RichContentFormatter.filterNewLines(input)
+        XCTAssertEqual(result, expected, "Newlines after emoji should be filtered")
+    }
+
+    func testRemoveTrailingBreakTagsWithEmoji() {
+        let input = "<p>Hello 👨‍👩‍👧‍👦👨‍👩‍👧‍👦 World</p><br><br> "
+        let expected = "<p>Hello 👨‍👩‍👧‍👦👨‍👩‍👧‍👦 World</p>"
+        let result = RichContentFormatter.removeTrailingBreakTags(input)
+        XCTAssertEqual(result, expected, "Trailing BR tags after emoji should be removed")
+    }
+
     func testFormatVideoTags() {
         let str1 = "<p>Some text.</p><video></video><p>Some text.</p>"
         let sanitizedStr1 = RichContentFormatter.formatVideoTags(str1) as NSString