1 files changed, 13 insertions, 10 deletions
diff --git a/SmartDeviceLink/SDLProtocolHeader.h b/SmartDeviceLink/SDLProtocolHeader.h
index dc8cbb788..97c405db2 100644
--- a/SmartDeviceLink/SDLProtocolHeader.h
+++ b/SmartDeviceLink/SDLProtocolHeader.h
@@ -37,26 +37,29 @@ typedef NS_ENUM(UInt8, SDLFrameData) {
     SDLFrameData_ConsecutiveLastFrame = 0x00
 };
 
+NS_ASSUME_NONNULL_BEGIN
 
 @interface SDLProtocolHeader : NSObject <NSCopying> {
     UInt8 _version;
     NSUInteger _size;
 }
 
-@property (assign, readonly) UInt8 version;
-@property (assign, readonly) NSUInteger size;
-@property (assign) BOOL compressed __deprecated_msg("This is a mirror for encrypted");
-@property (assign) BOOL encrypted;
-@property (assign) SDLFrameType frameType;
-@property (assign) SDLServiceType serviceType;
-@property (assign) SDLFrameData frameData;
-@property (assign) UInt8 sessionID;
-@property (assign) UInt32 bytesInPayload;
+@property (assign, nonatomic, readonly) UInt8 version;
+@property (assign, nonatomic, readonly) NSUInteger size;
+@property (assign, nonatomic) BOOL compressed __deprecated_msg("This is a mirror for encrypted");
+@property (assign, nonatomic) BOOL encrypted;
+@property (assign, nonatomic) SDLFrameType frameType;
+@property (assign, nonatomic) SDLServiceType serviceType;
+@property (assign, nonatomic) SDLFrameData frameData;
+@property (assign, nonatomic) UInt8 sessionID;
+@property (assign, nonatomic) UInt32 bytesInPayload;
 
 - (instancetype)init;
-- (NSData *)data;
+- (nullable NSData *)data;
 - (void)parse:(NSData *)data;
 - (NSString *)description;
 + (__kindof SDLProtocolHeader *)headerForVersion:(UInt8)version;
 
 @end
+
+NS_ASSUME_NONNULL_END