diff --git a/runtime/Swift/Sources/Antlr4/Parser.swift b/runtime/Swift/Sources/Antlr4/Parser.swift
index c3d913fdd1..db27484554 100644
--- a/runtime/Swift/Sources/Antlr4/Parser.swift
+++ b/runtime/Swift/Sources/Antlr4/Parser.swift
@@ -14,7 +14,7 @@ import Foundation
 ///
 /// - SeeAlso: `ATNDeserializationOptions.generateRuleBypassTransitions`
 ///
-private var bypassAltsAtnCache = [String: ATN]()
+private var bypassAltsAtnCache : ATN? = nil
 
 ///
 /// mutex for bypassAltsAtnCache updates
@@ -417,15 +417,15 @@ open class Parser: Recognizer<ParserATNSimulator> {
         let serializedAtn = getSerializedATN()
 
         return bypassAltsAtnCacheMutex.synchronized {
-            if let cachedResult = bypassAltsAtnCache[serializedAtn] {
+            if let cachedResult = bypassAltsAtnCache {
                 return cachedResult
             }
 
             var opts = ATNDeserializationOptions()
             opts.generateRuleBypassTransitions = true
             let result = try! ATNDeserializer(opts).deserialize(serializedAtn)
-            bypassAltsAtnCache[serializedAtn] = result
-            return result
+            bypassAltsAtnCache = result
+            return bypassAltsAtnCache!
         }
     }
 
diff --git a/runtime/Swift/Sources/Antlr4/Recognizer.swift b/runtime/Swift/Sources/Antlr4/Recognizer.swift
index bda3c257bd..4e3ff5d7f2 100644
--- a/runtime/Swift/Sources/Antlr4/Recognizer.swift
+++ b/runtime/Swift/Sources/Antlr4/Recognizer.swift
@@ -11,7 +11,7 @@ public protocol RecognizerProtocol {
     func getGrammarFileName() -> String
     func getParseInfo() -> ParseInfo?
     func getRuleNames() -> [String]
-    func getSerializedATN() -> String
+    func getSerializedATN() -> [Int]
     func getState() -> Int
     func getTokenType(_ tokenName: String) -> Int
     func getVocabulary() -> Vocabulary
@@ -95,7 +95,7 @@ open class Recognizer<ATNInterpreter: ATNSimulator>: RecognizerProtocol {
     /// For interpreters, we don't know their serialized ATN despite having
     /// created the interpreter from it.
     /// 
-    open func getSerializedATN() -> String {
+    open func getSerializedATN() -> [Int] {
         fatalError("there is no serialized ATN")
     }
 
diff --git a/runtime/Swift/Sources/Antlr4/atn/ATNDeserializer.swift b/runtime/Swift/Sources/Antlr4/atn/ATNDeserializer.swift
index 7c811d4159..96b176399f 100644
--- a/runtime/Swift/Sources/Antlr4/atn/ATNDeserializer.swift
+++ b/runtime/Swift/Sources/Antlr4/atn/ATNDeserializer.swift
@@ -4,13 +4,6 @@
 /// can be found in the LICENSE.txt file in the project root.
 ///
 
-
-
-///
-///
-/// -  Sam Harwell
-///
-
 import Foundation
 
 public class ATNDeserializer {
@@ -22,8 +15,8 @@ public class ATNDeserializer {
         self.deserializationOptions = deserializationOptions ?? ATNDeserializationOptions()
     }
 
-    public func deserialize(_ str: String) throws -> ATN {
-        let data = str.utf16.map { element in Int(element) }
+    public func deserialize(_ data: [Int]) throws -> ATN {
+//         let data = str.utf16.map { element in Int(element) }
         var p = 0
 
         let version = data[p]
diff --git a/runtime/Swift/Sources/Antlr4/misc/InterpreterDataReader.swift b/runtime/Swift/Sources/Antlr4/misc/InterpreterDataReader.swift
index 0a56c6743e..6857996f48 100644
--- a/runtime/Swift/Sources/Antlr4/misc/InterpreterDataReader.swift
+++ b/runtime/Swift/Sources/Antlr4/misc/InterpreterDataReader.swift
@@ -109,7 +109,7 @@ public class InterpreterDataReader {
         self.ruleNames = ruleNames
         self.channelNames = channelNames
         self.modeNames = modeNames
-        let atnSerialized = String(atnText.map{Character(UnicodeScalar(UInt16($0.trimmingCharacters(in:.whitespaces))!)!)})
+        let atnSerialized = atnText.map{Int($0.trimmingCharacters(in:.whitespaces))!}
         atn = try ATNDeserializer().deserialize(atnSerialized)
     }
         
diff --git a/tool/resources/org/antlr/v4/tool/templates/codegen/Swift/Swift.stg b/tool/resources/org/antlr/v4/tool/templates/codegen/Swift/Swift.stg
index 40235c0f00..fdfeb0477f 100755
--- a/tool/resources/org/antlr/v4/tool/templates/codegen/Swift/Swift.stg
+++ b/tool/resources/org/antlr/v4/tool/templates/codegen/Swift/Swift.stg
@@ -274,7 +274,7 @@ Parser_(parser, funcs, atn, sempredFuncs, ctor, superClass) ::= <<
 	func getRuleNames() -> [String] { return <parser.name>.ruleNames }
 
 	override <accessLevelOpenOK(parser)>
-	func getSerializedATN() -> String { return <parser.name>._serializedATN }
+	func getSerializedATN() -> [Int] { return <parser.name>._serializedATN }
 
 	override <accessLevelOpenOK(parser)>
 	func getATN() -> ATN { return <parser.name>._ATN }
@@ -1029,7 +1029,7 @@ Lexer(lexer, atn, actionFuncs, sempredFuncs, superClass) ::= <<
 	func getRuleNames() -> [String] { return <lexer.name>.ruleNames }
 
 	override <accessLevelOpenOK(lexer)>
-	func getSerializedATN() -> String { return <lexer.name>._serializedATN }
+	func getSerializedATN() -> [Int] { return <lexer.name>._serializedATN }
 
 	override <accessLevelOpenOK(lexer)>
 	func getChannelNames() -> [String] { return <lexer.name>.channelNames }
@@ -1049,9 +1049,9 @@ Lexer(lexer, atn, actionFuncs, sempredFuncs, superClass) ::= <<
 >>
 
 SerializedATN(model) ::= <<
-static let _serializedATN: String = """
-	<model.serialized; wrap={\\<\n>}>
-	"""
+static let _serializedATN:[Int] = [
+	<model.serialized: {s | <s>}; separator=",", wrap>
+]
 >>
 
 /** Using a type to init value map, try to init a type; if not in table
diff --git a/tool/src/org/antlr/v4/codegen/target/SwiftTarget.java b/tool/src/org/antlr/v4/codegen/target/SwiftTarget.java
index 54ae117162..aee548b335 100644
--- a/tool/src/org/antlr/v4/codegen/target/SwiftTarget.java
+++ b/tool/src/org/antlr/v4/codegen/target/SwiftTarget.java
@@ -104,7 +104,7 @@ public String toString(Object o, String formatString, Locale locale) {
 
 	@Override
 	public boolean isATNSerializedAsInts() {
-		return false;
+		return true;
 	}
 
 	@Override