diff --git a/Foundation/BUILD b/Foundation/BUILD
index 97a10d9d..e84a76ae 100644
--- a/Foundation/BUILD
+++ b/Foundation/BUILD
@@ -50,7 +50,7 @@ objc_library(
     hdrs = [
         "GTMLogger.h",
     ],
-    non_arc_srcs = [
+    srcs = [
         "GTMLogger.m",
     ],
     visibility = ["//visibility:public"],
@@ -78,7 +78,7 @@ objc_library(
     hdrs = [
         "GTMStringEncoding.h",
     ],
-    non_arc_srcs = [
+    srcs = [
         "GTMStringEncoding.m",
     ],
     visibility = ["//visibility:public"],
diff --git a/Foundation/GTMLogger.m b/Foundation/GTMLogger.m
index ae91c099..467cce2b 100644
--- a/Foundation/GTMLogger.m
+++ b/Foundation/GTMLogger.m
@@ -16,6 +16,10 @@
 //  the License.
 //
 
+#if !__has_feature(objc_arc)
+#error "This file needs to be compiled with ARC enabled."
+#endif
+
 #import "GTMLogger.h"
 #import <fcntl.h>
 #import <unistd.h>
@@ -45,16 +49,15 @@ @implementation GTMLogger
 + (instancetype)sharedLogger {
   @synchronized(self) {
     if (gSharedLogger == nil) {
-      gSharedLogger = [[self standardLogger] retain];
+      gSharedLogger = [self standardLogger];
     }
-    return [[gSharedLogger retain] autorelease];
+    return gSharedLogger;
   }
 }
 
 + (void)setSharedLogger:(GTMLogger *)logger {
   @synchronized(self) {
-    [gSharedLogger autorelease];
-    gSharedLogger = [logger retain];
+    gSharedLogger = logger;
   }
 }
 
@@ -62,12 +65,11 @@ + (instancetype)standardLogger {
   // Don't trust NSFileHandle not to throw
   @try {
     id<GTMLogWriter> writer = [NSFileHandle fileHandleWithStandardOutput];
-    id<GTMLogFormatter> fr = [[[GTMLogStandardFormatter alloc] init]
-                                 autorelease];
-    id<GTMLogFilter> filter = [[[GTMLogLevelFilter alloc] init] autorelease];
-    return [[[self alloc] initWithWriter:writer
+    id<GTMLogFormatter> fr = [[GTMLogStandardFormatter alloc] init];
+    id<GTMLogFilter> filter = [[GTMLogLevelFilter alloc] init];
+    return [[self alloc] initWithWriter:writer
                                formatter:fr
-                                  filter:filter] autorelease];
+                                  filter:filter];
   }
   @catch (id e) {
     // Ignored
@@ -97,25 +99,23 @@ + (instancetype)standardLoggerWithStdoutAndStderr {
 
   // Don't trust NSFileHandle not to throw
   @try {
-    GTMLogBasicFormatter *formatter = [[[GTMLogBasicFormatter alloc] init]
-                                          autorelease];
+    GTMLogBasicFormatter *formatter = [[GTMLogBasicFormatter alloc] init];
     GTMLogger *stdoutLogger =
         [self loggerWithWriter:[NSFileHandle fileHandleWithStandardOutput]
                      formatter:formatter
-                        filter:[[[GTMLogMaximumLevelFilter alloc]
+                        filter:[[GTMLogMaximumLevelFilter alloc]
                                   initWithMaximumLevel:kGTMLoggerLevelInfo]
-                                      autorelease]];
+        ];
     GTMLogger *stderrLogger =
         [self loggerWithWriter:[NSFileHandle fileHandleWithStandardError]
                      formatter:formatter
-                        filter:[[[GTMLogMininumLevelFilter alloc]
-                                  initWithMinimumLevel:kGTMLoggerLevelError]
-                                      autorelease]];
+                        filter:[[GTMLogMininumLevelFilter alloc]
+                                  initWithMinimumLevel:kGTMLoggerLevelError]];
     GTMLogger *compositeWriter =
         [self loggerWithWriter:[NSArray arrayWithObjects:
                                    stdoutLogger, stderrLogger, nil]
                      formatter:formatter
-                        filter:[[[GTMLogNoFilter alloc] init] autorelease]];
+                        filter:[[GTMLogNoFilter alloc] init]];
     GTMLogger *outerLogger = [self standardLogger];
     [outerLogger setWriter:compositeWriter];
     return outerLogger;
@@ -143,13 +143,13 @@ + (instancetype)standardLoggerWithPath:(NSString *)path {
 + (instancetype)loggerWithWriter:(id<GTMLogWriter>)writer
                        formatter:(id<GTMLogFormatter>)formatter
                           filter:(id<GTMLogFilter>)filter {
-  return [[[self alloc] initWithWriter:writer
+  return [[self alloc] initWithWriter:writer
                              formatter:formatter
-                                filter:filter] autorelease];
+                                filter:filter];
 }
 
 + (instancetype)logger {
-  return [[[self alloc] init] autorelease];
+  return [[self alloc] init];
 }
 
 - (instancetype)init {
@@ -170,46 +170,38 @@ - (instancetype)initWithWriter:(id<GTMLogWriter>)writer
 - (void)dealloc {
   // Unlikely, but |writer_| may be an NSFileHandle, which can throw
   @try {
-    [formatter_ release];
     [self notifyFilterBeforeDetachIfNeeded];
-    [filter_ release];
-    [writer_ release];
   }
   @catch (id e) {
     // Ignored
   }
-  [super dealloc];
 }
 
 - (id<GTMLogWriter>)writer {
-  return [[writer_ retain] autorelease];
+  return writer_;
 }
 
 - (void)setWriter:(id<GTMLogWriter>)writer {
   @synchronized(self) {
-    [writer_ autorelease];
     writer_ = nil;
     if (writer == nil) {
       // Try to use stdout, but don't trust NSFileHandle
       @try {
-        writer_ = [[NSFileHandle fileHandleWithStandardOutput] retain];
+        writer_ = [NSFileHandle fileHandleWithStandardOutput];
       }
       @catch (id e) {
         // Leave |writer_| nil
       }
-    } else {
-      writer_ = [writer retain];
     }
   }
 }
 
 - (id<GTMLogFormatter>)formatter {
-  return [[formatter_ retain] autorelease];
+  return formatter_;
 }
 
 - (void)setFormatter:(id<GTMLogFormatter>)formatter {
   @synchronized(self) {
-    [formatter_ autorelease];
     formatter_ = nil;
     if (formatter == nil) {
       @try {
@@ -218,20 +210,17 @@ - (void)setFormatter:(id<GTMLogFormatter>)formatter {
       @catch (id e) {
         // Leave |formatter_| nil
       }
-    } else {
-      formatter_ = [formatter retain];
     }
   }
 }
 
 - (id<GTMLogFilter>)filter {
-  return [[filter_ retain] autorelease];
+  return filter_;
 }
 
 - (void)setFilter:(id<GTMLogFilter>)filter {
   @synchronized(self) {
     [self notifyFilterBeforeDetachIfNeeded];
-    [filter_ autorelease];
     filter_ = nil;
     if (filter == nil) {
       @try {
@@ -240,8 +229,6 @@ - (void)setFilter:(id<GTMLogFilter>)filter {
       @catch (id e) {
         // Leave |filter_| nil
       }
-    } else {
-      filter_ = [filter retain];
     }
     [self notifyFilterAfterAttachIfNeeded];
   }
@@ -357,8 +344,8 @@ + (instancetype)fileHandleForLoggingAtPath:(NSString *)path mode:(mode_t)mode {
     fd = open([path fileSystemRepresentation], flags, mode);
   }
   if (fd == -1) return nil;
-  return [[[self alloc] initWithFileDescriptor:fd
-                                closeOnDealloc:YES] autorelease];
+  return [[self alloc] initWithFileDescriptor:fd
+                                closeOnDealloc:YES];
 }
 
 - (void)logMessage:(NSString *)msg level:(GTMLoggerLevel)level {
@@ -446,7 +433,7 @@ - (NSString *)stringForFunc:(NSString *)func
   // Performance note: We may want to do a quick check here to see if |fmt|
   // contains a '%', and if not, simply return 'fmt'.
   if (!(fmt && args)) return nil;
-  return [[[NSString alloc] initWithFormat:fmt arguments:args] autorelease];
+  return [[NSString alloc] initWithFormat:fmt arguments:args];
 }
 
 @end  // GTMLogBasicFormatter
@@ -462,19 +449,12 @@ - (instancetype)init {
     pname_ = [[[NSProcessInfo processInfo] processName] copy];
     pid_ = [[NSProcessInfo processInfo] processIdentifier];
     if (!(dateFormatter_ && pname_)) {
-      [self release];
       return nil;
     }
   }
   return self;
 }
 
-- (void)dealloc {
-  [dateFormatter_ release];
-  [pname_ release];
-  [super dealloc];
-}
-
 - (NSString *)stringForFunc:(NSString *)func
                  withFormat:(NSString *)fmt
                      valist:(va_list)args
@@ -542,8 +522,6 @@ - (void)dealloc {
                 @"`willDetachFromLogger` call because those methods "
                 @"register/unregister the `GTMLogLevelFilter` instance as an "
                 @"observer of the user defaults instance.");
-
-  [super dealloc];
 }
 
 // In DEBUG builds, log everything. If we're not in a debug build we'll assume
@@ -610,7 +588,7 @@ - (void)startObservingUserDefaultsIfNeeded {
   // clear settings:
   // https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Classes/NSUserDefaults_Class/index.html#//apple_ref/occ/clm/NSUserDefaults/resetStandardUserDefaults
   // and so should only be called in test code if necessary.
-  userDefaults_ = [[NSUserDefaults standardUserDefaults] retain];
+  userDefaults_ = [NSUserDefaults standardUserDefaults];
   [userDefaults_ addObserver:self
                   forKeyPath:kVerboseLoggingKey
                      options:NSKeyValueObservingOptionInitial
@@ -623,7 +601,6 @@ - (void)stopObservingUserDefaultsIfNeeded {
   }
 
   [userDefaults_ removeObserver:self forKeyPath:kVerboseLoggingKey];
-  [userDefaults_ release];
   userDefaults_ = nil;
 }
 
@@ -655,7 +632,6 @@ @implementation GTMLogAllowedLevelFilter
 - (instancetype)initWithAllowedLevels:(NSIndexSet *)levels {
   self = [super init];
   if (self != nil) {
-    allowedLevels_ = [levels retain];
     // Cap min/max level
     if (!allowedLevels_ ||
         // NSIndexSet is unsigned so only check the high bound, but need to
@@ -663,7 +639,6 @@ - (instancetype)initWithAllowedLevels:(NSIndexSet *)levels {
         // wraparound.
         ([allowedLevels_ firstIndex] > kGTMLoggerLevelAssert) ||
         ([allowedLevels_ lastIndex] > kGTMLoggerLevelAssert)) {
-      [self release];
       return nil;
     }
   }
@@ -677,11 +652,6 @@ - (instancetype)init {
                  (kGTMLoggerLevelAssert - kGTMLoggerLevelUnknown + 1))]];
 }
 
-- (void)dealloc {
-  [allowedLevels_ release];
-  [super dealloc];
-}
-
 - (BOOL)filterAllowsMessage:(NSString *)msg level:(GTMLoggerLevel)level {
   return [allowedLevels_ containsIndex:level];
 }
diff --git a/Foundation/GTMStringEncoding.m b/Foundation/GTMStringEncoding.m
index 89a590bf..0d901fac 100644
--- a/Foundation/GTMStringEncoding.m
+++ b/Foundation/GTMStringEncoding.m
@@ -16,6 +16,10 @@
 //  the License.
 //
 
+#if !__has_feature(objc_arc)
+#error "This file needs to be compiled with ARC enabled."
+#endif
+
 #import "GTMStringEncoding.h"
 
 NSString *const GTMStringEncodingErrorDomain = @"com.google.GTMStringEncodingErrorDomain";
@@ -92,22 +96,20 @@ GTM_INLINE int lcm(int a, int b) {
 }
 
 + (instancetype)stringEncodingWithString:(NSString *)string {
-  return [[[self alloc] initWithString:string] autorelease];
+  return [[self alloc] initWithString:string];
 }
 
 - (instancetype)initWithString:(NSString *)string {
   if ((self = [super init])) {
-    charMapData_ = [[string dataUsingEncoding:NSASCIIStringEncoding] retain];
+    charMapData_ = [string dataUsingEncoding:NSASCIIStringEncoding];
     if (!charMapData_) {
       _GTMDevLog(@"Unable to convert string to ASCII");
-      [self release];
       return nil;
     }
     charMap_ = (char *)[charMapData_ bytes];
     NSUInteger length = [charMapData_ length];
     if (length < 2 || length > 128 || length & (length - 1)) {
       _GTMDevLog(@"Length not a power of 2 between 2 and 128");
-      [self release];
       return nil;
     }
 
@@ -115,7 +117,6 @@ - (instancetype)initWithString:(NSString *)string {
     for (unsigned int i = 0; i < length; i++) {
       if (reverseCharMap_[(int)charMap_[i]] != kUnknownChar) {
         _GTMDevLog(@"Duplicate character at pos %d", i);
-        [self release];
         return nil;
       }
       reverseCharMap_[(int)charMap_[i]] = i;
@@ -129,11 +130,6 @@ - (instancetype)initWithString:(NSString *)string {
   return self;
 }
 
-- (void)dealloc {
-  [charMapData_ release];
-  [super dealloc];
-}
-
 - (NSString *)description {
   // TODO(iwade) track synonyms
   return [NSString stringWithFormat:@"<Base%d StringEncoder: %@>",
@@ -218,8 +214,8 @@ - (NSString *)encode:(NSData *)inData error:(NSError **)error {
 
   [outData setLength:outPos];
 
-  NSString *value = [[[NSString alloc] initWithData:outData
-                                           encoding:NSASCIIStringEncoding] autorelease];
+  NSString *value = [[NSString alloc] initWithData:outData
+                                         encoding:NSASCIIStringEncoding];
   if (!value) {
     if (error) {
       *error = [NSError errorWithDomain:GTMStringEncodingErrorDomain
@@ -328,8 +324,7 @@ - (NSString *)stringByDecoding:(NSString *)inString error:(NSError **)error {
   NSData *ret = [self decode:inString error:error];
   NSString *value = nil;
   if (ret) {
-    value = [[[NSString alloc] initWithData:ret
-                                   encoding:NSUTF8StringEncoding] autorelease];
+    value = [[NSString alloc] initWithData:ret encoding:NSUTF8StringEncoding];
   }
   return value;
 }
diff --git a/GoogleToolboxForMac.podspec b/GoogleToolboxForMac.podspec
index af68560b..21e0794f 100644
--- a/GoogleToolboxForMac.podspec
+++ b/GoogleToolboxForMac.podspec
@@ -75,6 +75,7 @@ Pod::Spec.new do |s|
 
   s.subspec 'Logger' do |sp|
     sp.source_files = 'Foundation/GTMLogger.{h,m}'
+    sp.requires_arc = 'Foundation/GTMLogger.{h,m}'
     sp.dependency 'GoogleToolboxForMac/Defines', "#{s.version}"
     sp.resource_bundle = {
       "GoogleToolboxForMac_Logger_Privacy" => "Resources/Logger/PrivacyInfo.xcprivacy"
@@ -98,6 +99,7 @@ Pod::Spec.new do |s|
 
   s.subspec 'StringEncoding' do |sp|
     sp.source_files = 'Foundation/GTMStringEncoding.{h,m}'
+    sp.requires_arc = 'Foundation/GTMStringEncoding.{h,m}'
     sp.dependency 'GoogleToolboxForMac/Defines', "#{s.version}"
   end
 
diff --git a/Package.swift b/Package.swift
new file mode 100644
index 00000000..21a07f20
--- /dev/null
+++ b/Package.swift
@@ -0,0 +1,56 @@
+// swift-tools-version:6.0
+import PackageDescription
+
+let package = Package(
+    name: "GoogleToolboxForMac",
+    platforms: [
+        .iOS(.v13),
+        .macOS(.v10_15),
+        .tvOS(.v13),
+    ],
+    products: [
+        .library(
+            name: "GTMLogger",
+            targets: ["GTMLogger"]
+        ),
+        .library(
+            name: "GTMNSData_zlib",
+            targets: ["GTMNSData_zlib"]
+        ),
+        .library(
+            name: "GTMStringEncoding",
+            targets: ["GTMStringEncoding"]
+        ),
+    ],
+    targets: [
+        .target(
+            name: "GTMDefines",
+            path: "spm/GTMDefines"
+        ),
+        .target(
+            name: "GTMLogger",
+            dependencies: [
+                "GTMDefines"
+            ],
+            path: "spm/GTMLogger"
+
+        ),
+        .target(
+            name: "GTMNSData_zlib",
+            dependencies: [
+                "GTMDefines"
+            ],
+            path: "spm/GTMNSData_zlib",
+            linkerSettings: [
+                .linkedLibrary("z")
+            ]
+        ),
+        .target(
+            name: "GTMStringEncoding",
+            dependencies: [
+                "GTMDefines"
+            ],
+            path: "spm/GTMStringEncoding"
+        ),
+    ]
+)
diff --git a/spm/GTMDefines/GTMDefines.m b/spm/GTMDefines/GTMDefines.m
new file mode 100644
index 00000000..c49c6839
--- /dev/null
+++ b/spm/GTMDefines/GTMDefines.m
@@ -0,0 +1 @@
+#import "GTMDefines.h"
diff --git a/spm/GTMDefines/include/GTMDefines.h b/spm/GTMDefines/include/GTMDefines.h
new file mode 120000
index 00000000..e8bf00b4
--- /dev/null
+++ b/spm/GTMDefines/include/GTMDefines.h
@@ -0,0 +1 @@
+../../../GTMDefines.h
\ No newline at end of file
diff --git a/spm/GTMLogger/GTMLogger.m b/spm/GTMLogger/GTMLogger.m
new file mode 120000
index 00000000..f7b83c3e
--- /dev/null
+++ b/spm/GTMLogger/GTMLogger.m
@@ -0,0 +1 @@
+../../Foundation/GTMLogger.m
\ No newline at end of file
diff --git a/spm/GTMLogger/include/GTMLogger.h b/spm/GTMLogger/include/GTMLogger.h
new file mode 120000
index 00000000..da377375
--- /dev/null
+++ b/spm/GTMLogger/include/GTMLogger.h
@@ -0,0 +1 @@
+../../../Foundation/GTMLogger.h
\ No newline at end of file
diff --git a/spm/GTMNSData_zlib/GTMNSData+zlib.m b/spm/GTMNSData_zlib/GTMNSData+zlib.m
new file mode 120000
index 00000000..b750715f
--- /dev/null
+++ b/spm/GTMNSData_zlib/GTMNSData+zlib.m
@@ -0,0 +1 @@
+../../Foundation/GTMNSData+zlib.m
\ No newline at end of file
diff --git a/spm/GTMNSData_zlib/include/GTMNSData+zlib.h b/spm/GTMNSData_zlib/include/GTMNSData+zlib.h
new file mode 120000
index 00000000..07009467
--- /dev/null
+++ b/spm/GTMNSData_zlib/include/GTMNSData+zlib.h
@@ -0,0 +1 @@
+../../../Foundation/GTMNSData+zlib.h
\ No newline at end of file
diff --git a/spm/GTMStringEncoding/GTMStringEncoding.m b/spm/GTMStringEncoding/GTMStringEncoding.m
new file mode 120000
index 00000000..5446598e
--- /dev/null
+++ b/spm/GTMStringEncoding/GTMStringEncoding.m
@@ -0,0 +1 @@
+../../Foundation/GTMStringEncoding.m
\ No newline at end of file
diff --git a/spm/GTMStringEncoding/include/GTMStringEncoding.h b/spm/GTMStringEncoding/include/GTMStringEncoding.h
new file mode 120000
index 00000000..476ce5db
--- /dev/null
+++ b/spm/GTMStringEncoding/include/GTMStringEncoding.h
@@ -0,0 +1 @@
+../../../Foundation/GTMStringEncoding.h
\ No newline at end of file