Make NSAttributedString extension allow multiple palceholder string replacements (IOS-140)

MastodonSDK/Sources/MastodonUI/Extension/NSAttributedString+Format.swift

@@ -6,11 +6,42 @@ public extension NSAttributedString {
     convenience init(format: NSAttributedString, args: NSAttributedString...) {
         let mutableNSAttributedString = NSMutableAttributedString(attributedString: format)
 
-        args.forEach { attributedString in
-            let range = NSString(string: mutableNSAttributedString.string).range(of: "%@")
-            mutableNSAttributedString.replaceCharacters(in: range, with: attributedString)
+        zip(format.string.ranges(of: "%@"), Array(args)).forEach { range, arg in
+            mutableNSAttributedString.replaceCharacters(in: .init(range: range, originalText: format.string), with: arg)
         }
-        
+
         self.init(attributedString: mutableNSAttributedString)
     }
 }
+
+private extension String {
+    func ranges(of searchString: String) -> [Range<String.Index>] {
+        let indices = indices(of: searchString)
+        let count = searchString.count
+        return indices.map({ index(startIndex, offsetBy: $0)..<index(startIndex, offsetBy: $0+count) })
+    }
+    
+    func indices(of occurrence: String) -> [Int] {
+        var indices = [Int]()
+        var position = startIndex
+        while let range = range(of: occurrence, range: position..<endIndex) {
+            let i = distance(from: startIndex, to: range.lowerBound)
+            indices.append(i)
+            let offset = occurrence.distance(from: occurrence.startIndex, to: occurrence.endIndex) - 1
+            guard let after = index(range.lowerBound, offsetBy: offset, limitedBy: endIndex) else {
+                break
+            }
+            position = index(after: after)
+        }
+        return indices
+    }
+}
+
+private extension NSRange {
+    init(range: Range<String.Index>, originalText: String) {
+        self.init(
+            location: range.lowerBound.utf16Offset(in: originalText),
+            length: range.upperBound.utf16Offset(in: originalText) - range.lowerBound.utf16Offset(in: originalText)
+        )
+    }
+}