diff --git a/Cassette.xcodeproj/project.pbxproj b/Cassette.xcodeproj/project.pbxproj
index 09f6548..a75268a 100644
--- a/Cassette.xcodeproj/project.pbxproj
+++ b/Cassette.xcodeproj/project.pbxproj
@@ -36,6 +36,7 @@
 		6E126C031B1F816300856CCA /* CASQueueFileTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 6E126C021B1F816300856CCA /* CASQueueFileTests.m */; };
 		6E126C0E1B1F818100856CCA /* CASQueueFile.h in Headers */ = {isa = PBXBuildFile; fileRef = 6E126C0C1B1F818100856CCA /* CASQueueFile.h */; };
 		6E126C0F1B1F818100856CCA /* CASQueueFile.m in Sources */ = {isa = PBXBuildFile; fileRef = 6E126C0D1B1F818100856CCA /* CASQueueFile.m */; };
+		86D0403326BC33D5009A1615 /* CASSwiftChanges.swift in Sources */ = {isa = PBXBuildFile; fileRef = 86D0403226BC33D5009A1615 /* CASSwiftChanges.swift */; };
 		91C04B422677CA8000874F5E /* CASDataSerializer.h in Headers */ = {isa = PBXBuildFile; fileRef = 91C04B412677CA8000874F5E /* CASDataSerializer.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		91C04B482677CB8700874F5E /* CASDefaultDataSerializer.h in Headers */ = {isa = PBXBuildFile; fileRef = 91C04B462677CB8700874F5E /* CASDefaultDataSerializer.h */; };
 		91C04B492677CB8700874F5E /* CASDefaultDataSerializer.m in Sources */ = {isa = PBXBuildFile; fileRef = 91C04B472677CB8700874F5E /* CASDefaultDataSerializer.m */; };
@@ -114,6 +115,8 @@
 		6E126C0C1B1F818100856CCA /* CASQueueFile.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = CASQueueFile.h; sourceTree = "<group>"; };
 		6E126C0D1B1F818100856CCA /* CASQueueFile.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = CASQueueFile.m; sourceTree = "<group>"; };
 		7F66F602AB0D8B57684B1FDD /* Pods-Cassette.debug.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-Cassette.debug.xcconfig"; path = "Target Support Files/Pods-Cassette/Pods-Cassette.debug.xcconfig"; sourceTree = "<group>"; };
+		86D0402F26BC338D009A1615 /* CassetteTests-Bridging-Header.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = "CassetteTests-Bridging-Header.h"; sourceTree = "<group>"; };
+		86D0403226BC33D5009A1615 /* CASSwiftChanges.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CASSwiftChanges.swift; sourceTree = "<group>"; };
 		91C04B412677CA8000874F5E /* CASDataSerializer.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = CASDataSerializer.h; sourceTree = "<group>"; };
 		91C04B462677CB8700874F5E /* CASDefaultDataSerializer.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = CASDefaultDataSerializer.h; sourceTree = "<group>"; };
 		91C04B472677CB8700874F5E /* CASDefaultDataSerializer.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = CASDefaultDataSerializer.m; sourceTree = "<group>"; };
@@ -253,6 +256,8 @@
 				6E126C021B1F816300856CCA /* CASQueueFileTests.m */,
 				3C4A836F2311DD4000D06FAE /* CASFileObjectQueueTests.m */,
 				3C4A83792313075000D06FAE /* CASInMemoryObjectQueueTests.m */,
+				86D0403226BC33D5009A1615 /* CASSwiftChanges.swift */,
+				86D0402F26BC338D009A1615 /* CassetteTests-Bridging-Header.h */,
 			);
 			path = CassetteTests;
 			sourceTree = "<group>";
@@ -416,6 +421,7 @@
 					6E126BFA1B1F816300856CCA = {
 						CreatedOnToolsVersion = 6.3.1;
 						DevelopmentTeam = 57Y47U492U;
+						LastSwiftMigration = 1250;
 					};
 					92FAF8E126A355BE00EF78A7 = {
 						CreatedOnToolsVersion = 12.5;
@@ -554,6 +560,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				3C4A83702311DD4000D06FAE /* CASFileObjectQueueTests.m in Sources */,
+				86D0403326BC33D5009A1615 /* CASSwiftChanges.swift in Sources */,
 				3C4A837A2313075000D06FAE /* CASInMemoryObjectQueueTests.m in Sources */,
 				6E126C031B1F816300856CCA /* CASQueueFileTests.m in Sources */,
 			);
@@ -816,6 +823,7 @@
 			isa = XCBuildConfiguration;
 			baseConfigurationReference = 20064E82733FF0AC4F765955 /* Pods-Cassette-CassetteTests.debug.xcconfig */;
 			buildSettings = {
+				CLANG_ENABLE_MODULES = YES;
 				FRAMEWORK_SEARCH_PATHS = (
 					"$(SDKROOT)/Developer/Library/Frameworks",
 					"$(inherited)",
@@ -831,6 +839,9 @@
 					"@loader_path/Frameworks",
 				);
 				PRODUCT_NAME = "$(TARGET_NAME)";
+				SWIFT_OBJC_BRIDGING_HEADER = "CassetteTests/CassetteTests-Bridging-Header.h";
+				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
+				SWIFT_VERSION = 5.0;
 			};
 			name = Debug;
 		};
@@ -838,6 +849,7 @@
 			isa = XCBuildConfiguration;
 			baseConfigurationReference = 0D910F2975ED908A5492A170 /* Pods-Cassette-CassetteTests.release.xcconfig */;
 			buildSettings = {
+				CLANG_ENABLE_MODULES = YES;
 				FRAMEWORK_SEARCH_PATHS = (
 					"$(SDKROOT)/Developer/Library/Frameworks",
 					"$(inherited)",
@@ -849,6 +861,8 @@
 					"@loader_path/Frameworks",
 				);
 				PRODUCT_NAME = "$(TARGET_NAME)";
+				SWIFT_OBJC_BRIDGING_HEADER = "CassetteTests/CassetteTests-Bridging-Header.h";
+				SWIFT_VERSION = 5.0;
 			};
 			name = Release;
 		};
diff --git a/Cassette/CASObjectQueue.h b/Cassette/CASObjectQueue.h
index 24cc8b6..9ca4ab3 100644
--- a/Cassette/CASObjectQueue.h
+++ b/Cassette/CASObjectQueue.h
@@ -22,14 +22,14 @@ NS_ASSUME_NONNULL_BEGIN
  * Closes the queue. Do not use this object after this method returns.
  * Returns YES on success. On failure, returns NO and sets *error to the error.
  */
-- (BOOL)closeAndReturnError:(NSError * __autoreleasing * _Nullable)error;
+- (BOOL)closeAndReturnError:(NSError * __autoreleasing * _Nullable)error NS_SWIFT_NAME(close());
 
 /**
  * Adds an element to the end of the queue.
  *
  * Please use the API @c add:error: instead.
  */
-- (void)add:(T)data __attribute__((deprecated("Use -add:error: instead.")));
+- (void)add:(T)data __attribute__((deprecated("Use -add:error: instead."))) NS_SWIFT_UNAVAILABLE("Not available in Swift");
 
 /**
  * Adds an element to the end of the queue.
@@ -59,7 +59,13 @@ NS_ASSUME_NONNULL_BEGIN
  *
  * Please use the API @c peek:error: instead.
  */
-- (nullable T)peek __attribute__((deprecated("Use -peek:error: instead.")));
+- (nullable T)peek __attribute__((deprecated("Use -peek:error: instead."))) NS_SWIFT_UNAVAILABLE("Not available in Swift");
+
+/**
+ * Returns the head of the queue, or nil if the queue is empty. Does not modify the
+ * queue.
+ */
+- (nullable T)peekWithError:(NSError * __autoreleasing * _Nullable)error NS_SWIFT_NAME(peek());
 
 /**
  * Reads up to the specified amount of entries from the head of the queue without removing
@@ -69,7 +75,7 @@ NS_ASSUME_NONNULL_BEGIN
  *
  * Please use the API @c peek:error: instead.
  */
-- (NSArray<T> *)peek:(NSUInteger)amount __attribute__((deprecated("Use -peek:error: instead.")));
+- (NSArray<T> *)peek:(NSUInteger)amount __attribute__((deprecated("Use -peek:error: instead."))) NS_SWIFT_UNAVAILABLE("Not available in Swift");
 
 /**
  * Reads up to the specified amount of entries from the head of the queue without removing
@@ -86,14 +92,14 @@ NS_ASSUME_NONNULL_BEGIN
  *
  * Please use the API @c pop:error: instead.
  */
-- (void)pop __attribute__((deprecated("Use -pop:error: instead.")));;
+- (void)pop __attribute__((deprecated("Use -pop:error: instead."))) NS_SWIFT_UNAVAILABLE("Not available in Swift");;
 
 /**
  * Removes the specified amount of entries from the head of the queue.
  *
  * Please use the API @c pop:error: instead.
  */
-- (void)pop:(NSUInteger)amount __attribute__((deprecated("Use -peek:error: instead.")));
+- (void)pop:(NSUInteger)amount __attribute__((deprecated("Use -peek:error: instead."))) NS_SWIFT_UNAVAILABLE("Not available in Swift");
 
 /**
  * Removes the specified amount of entries from the head of the queue.
@@ -106,13 +112,13 @@ NS_ASSUME_NONNULL_BEGIN
  *
  * Please use the API @c clearAndReturnError: instead.
  */
-- (void)clear __attribute__((deprecated("Use -clearAndReturnError: instead.")));;
+- (void)clear __attribute__((deprecated("Use -clearAndReturnError: instead."))) NS_SWIFT_UNAVAILABLE("Not available in Swift");
 
 /**
  * Clears this queue. Truncates the file to the initial size.
  * Returns YES on success. On failure, returns NO and sets *error to the error.
  */
-- (BOOL)clearAndReturnError:(NSError * __autoreleasing * _Nullable)error;
+- (BOOL)clearAndReturnError:(NSError * __autoreleasing * _Nullable)error NS_SWIFT_NAME(clear());
 
 @end
 
diff --git a/Cassette/CASObjectQueue.m b/Cassette/CASObjectQueue.m
index 55ec9ba..c294e59 100644
--- a/Cassette/CASObjectQueue.m
+++ b/Cassette/CASObjectQueue.m
@@ -46,6 +46,10 @@ - (id)peek {
     return [self peek:1 error:NULL].firstObject;
 }
 
+- (id)peekWithError:(NSError * __autoreleasing * _Nullable)error {
+    return [self peek:1 error:error].firstObject;
+}
+
 - (NSArray<id> *)peek:(NSUInteger)amount {
     return [self peek:amount error:NULL] ?: @[];
 }
diff --git a/Cassette/CASQueueFile.h b/Cassette/CASQueueFile.h
index 52f408c..1e9f083 100644
--- a/Cassette/CASQueueFile.h
+++ b/Cassette/CASQueueFile.h
@@ -38,14 +38,14 @@ NS_ASSUME_NONNULL_BEGIN
  * Closes the queue file. Do not use this object after this method returns.
  * Returns YES on success. On failure, returns NO and sets *error to the error.
  */
-- (BOOL)closeAndReturnError:(NSError * __autoreleasing * _Nullable)error;
+- (BOOL)closeAndReturnError:(NSError * __autoreleasing * _Nullable)error NS_SWIFT_NAME(close());
 
 /**
  * Adds an element to the end of the queue.
  *
  * Please use the API @c add:error: instead.
  */
-- (void)add:(NSData *)data __attribute__((deprecated("Use -add:error: instead.")));
+- (void)add:(NSData *)data __attribute__((deprecated("Use -add:error: instead."))) NS_SWIFT_UNAVAILABLE("Not available in Swift");
 
 /**
  * Adds an element to the end of the queue.
@@ -77,7 +77,7 @@ NS_ASSUME_NONNULL_BEGIN
  *
  * Please use the API @c peek:error: instead.
  */
-- (NSArray<NSData *> *)peek:(NSUInteger)amount __attribute__((deprecated("Use peek:error: instead.")));
+- (NSArray<NSData *> *)peek:(NSUInteger)amount __attribute__((deprecated("Use peek:error: instead."))) NS_SWIFT_UNAVAILABLE("Not available in Swift");
 
 /**
  * Reads up to the specified amount of entries from the head of the queue without removing
@@ -94,7 +94,7 @@ NS_ASSUME_NONNULL_BEGIN
  *
  * Please use the API @c pop:error: instead.
  */
-- (void)pop:(NSUInteger)amount __attribute__((deprecated("Use -pop:error: instead.")));
+- (void)pop:(NSUInteger)amount __attribute__((deprecated("Use -pop:error: instead."))) NS_SWIFT_UNAVAILABLE("Not available in Swift");
 
 /**
  * Removes the specified amount of entries from the head of the queue.
@@ -107,13 +107,13 @@ NS_ASSUME_NONNULL_BEGIN
  *
  * Please use the API @c clearAndReturnError: instead.
  */
-- (void)clear __attribute__((deprecated("Use -clearAndReturnError: instead.")));
+- (void)clear __attribute__((deprecated("Use -clearAndReturnError: instead."))) NS_SWIFT_UNAVAILABLE("Not available in Swift");
 
 /**
  * Clears this queue. Truncates the file to the initial size.
  * Returns YES on success. On failure, returns NO and sets *error to the error.
  */
-- (BOOL)clearAndReturnError:(NSError * __autoreleasing * _Nullable)error;
+- (BOOL)clearAndReturnError:(NSError * __autoreleasing * _Nullable)error NS_SWIFT_NAME(clear());
 
 @end
 
diff --git a/CassetteTests/CASSwiftChanges.swift b/CassetteTests/CASSwiftChanges.swift
new file mode 100644
index 0000000..7e7923d
--- /dev/null
+++ b/CassetteTests/CASSwiftChanges.swift
@@ -0,0 +1,75 @@
+//
+//  CASSwiftChanges.swift
+//  CassetteTests
+//
+//  Created by Alfons Hoogervorst on 05/08/2021.
+//
+
+import XCTest
+import Cassette
+
+class CASSwiftChanges: XCTestCase {
+    
+    override func setUpWithError() throws {
+        // Put setup code here. This method is called before the invocation of each test method in the class.
+    }
+
+    override func tearDownWithError() throws {
+        // Put teardown code here. This method is called after the invocation of each test method in the class.
+    }
+    
+    fileprivate func testOperations(with queue: CASObjectQueue<NSNumber>) {
+        try? queue.add(1)
+        try? queue.add(2)
+        try? queue.add(3)
+        XCTAssert(queue.size() == 3, "Should contain 3 elements")
+        try? queue.pop(1)
+        let secondValue = try? queue.peek()
+        XCTAssert(secondValue == 2, "Should be value 2")
+        try? queue.clear()
+        XCTAssert(queue.size() == 0, "Should have zero items")
+        try? queue.add(NSNumber(integerLiteral: 2))
+        XCTAssert(queue.size() == 1, "Should have 1 item")
+        try? queue.clear()
+        XCTAssert(queue.size() == 0, "Should have zero items")
+        try? queue.add(4)
+        let fourthValue = try? queue.peek()
+        XCTAssert(fourthValue == 4, "Should be value 4")
+        try? queue.pop(1)
+        XCTAssertThrowsError(try queue.peek(), "Should throw an error")
+    }
+
+    func testChangesCASInMemoryQueue() throws {
+        let queue = CASInMemoryObjectQueue<NSNumber>()
+        self.testOperations(with: queue)
+    }
+    
+    func testChangesCASFileObjectQueue() throws {
+        let queueFileName = "\(NSTemporaryDirectory())/\(UUID().uuidString)"
+        // remove old remnants
+        try? FileManager.default.removeItem(atPath: queueFileName)
+        let queue = try? CASFileObjectQueue<NSNumber>(absolutePath: queueFileName)
+        XCTAssertNotNil(queue)
+        self.testOperations(with: queue!)
+    }
+
+    func testChangesCASFileObjectQueueReopen() throws {
+        let queueFileName = "\(NSTemporaryDirectory())/\(UUID().uuidString)"
+        // remove old remnants
+        try? FileManager.default.removeItem(atPath: queueFileName)
+        let queue = try? CASFileObjectQueue<NSNumber>(absolutePath: queueFileName)
+        XCTAssertNotNil(queue)
+        self.testOperations(with: queue!)
+        try? queue?.add(5)
+        XCTAssertNoThrow(try queue?.close())
+        let reopenedQueue = try? CASFileObjectQueue<NSNumber>(absolutePath: queueFileName)
+        XCTAssertNotNil(reopenedQueue)
+        let value = try? reopenedQueue?.peek(5)
+        XCTAssertNotNil(value)
+        XCTAssert(value!.count == 1, "Array with one element")
+        XCTAssertNoThrow(try reopenedQueue?.pop(1))
+        XCTAssert(reopenedQueue!.size() == 0, "Should now have no contents.")
+        XCTAssert(value!.first == 5, "Value should be 5")
+    }
+
+}
diff --git a/CassetteTests/CassetteTests-Bridging-Header.h b/CassetteTests/CassetteTests-Bridging-Header.h
new file mode 100644
index 0000000..66c9874
--- /dev/null
+++ b/CassetteTests/CassetteTests-Bridging-Header.h
@@ -0,0 +1,6 @@
+//
+//  Use this file to import your target's public headers that you would like to expose to Swift.
+//
+
+#import "Cassette.h"
+#import "CASQueueFile.h"