diff --git a/Pod/Classes/NSDictionary+QueryString.h b/Pod/Classes/NSDictionary+QueryString.h
index 59c7a68..92c928c 100644
--- a/Pod/Classes/NSDictionary+QueryString.h
+++ b/Pod/Classes/NSDictionary+QueryString.h
@@ -8,7 +8,11 @@
 
 #import <Foundation/Foundation.h>
 
+NS_ASSUME_NONNULL_BEGIN
+
 @interface NSDictionary (QueryString)
 + (NSDictionary *)dictionaryWithQueryString:(NSString *)queryString;
 - (NSString *)queryStringValue;
 @end
+
+NS_ASSUME_NONNULL_END
diff --git a/Pod/Classes/NSDictionary+QueryString.m b/Pod/Classes/NSDictionary+QueryString.m
index 28fe181..3a3dc20 100644
--- a/Pod/Classes/NSDictionary+QueryString.m
+++ b/Pod/Classes/NSDictionary+QueryString.m
@@ -11,8 +11,7 @@
 
 @implementation NSDictionary (QueryString)
 
-+ (NSDictionary *)dictionaryWithQueryString:(NSString *)queryString
-{
++ (NSDictionary *)dictionaryWithQueryString:(NSString *)queryString {
     NSMutableDictionary *dictionary = [NSMutableDictionary dictionary];
     NSArray *pairs = [queryString componentsSeparatedByString:@"&"];
     
@@ -26,11 +25,13 @@ + (NSDictionary *)dictionaryWithQueryString:(NSString *)queryString
             NSString *decodedKey = [key URLDecodedString];
             NSString *decodedValue = [value URLDecodedString];
             
-            if (![key isEqualToString:decodedKey])
+            if (![key isEqualToString:decodedKey]) {
                 key = decodedKey;
+            }
             
-            if (![value isEqualToString:decodedValue])
+            if (![value isEqualToString:decodedValue]) {
                 value = decodedValue;
+            }
             
             [dictionary setObject:value forKey:key];
         }
@@ -39,8 +40,7 @@ + (NSDictionary *)dictionaryWithQueryString:(NSString *)queryString
     return [NSDictionary dictionaryWithDictionary:dictionary];
 }
 
-- (NSString *)queryStringValue
-{
+- (NSString *)queryStringValue {
     NSMutableArray *pairs = [NSMutableArray array];
     for (NSString *key in [self keyEnumerator])
     {
diff --git a/Pod/Classes/NSString+URLEncoding.h b/Pod/Classes/NSString+URLEncoding.h
index 96d4a7f..18435ab 100644
--- a/Pod/Classes/NSString+URLEncoding.h
+++ b/Pod/Classes/NSString+URLEncoding.h
@@ -8,7 +8,11 @@
 
 #import <Foundation/Foundation.h>
 
+NS_ASSUME_NONNULL_BEGIN
+
 @interface NSString (URLEncoding)
 - (NSString *)URLEncodedString;
 - (NSString *)URLDecodedString;
 @end
+
+NS_ASSUME_NONNULL_END
diff --git a/Pod/Classes/PhxChannel.h b/Pod/Classes/PhxChannel.h
index fcf8dce..a0d6d91 100644
--- a/Pod/Classes/PhxChannel.h
+++ b/Pod/Classes/PhxChannel.h
@@ -9,6 +9,7 @@
 #import <Foundation/Foundation.h>
 #import "PhxTypes.h"
 
+NS_ASSUME_NONNULL_BEGIN
 
 @class PhxSocket;
 @class PhxChannel;
@@ -26,12 +27,12 @@
 @property (nonatomic, weak) id<PhxChannelDelegate> delegate;
 @property (nonatomic, weak) PhxSocket* socket;
 @property (nonatomic, readonly) ChannelState state;
-@property (nonatomic, retain) NSString* topic;
-@property (nonatomic, retain) NSDictionary *params;
+@property (nonatomic, strong) NSString* topic;
+@property (nonatomic, strong) NSDictionary *params;
 
-- (id)initWithSocket:(PhxSocket*)socket
-               topic:(NSString*)topic
-              params:(NSDictionary*)params;
+- (instancetype)initWithSocket:(PhxSocket*)socket
+                         topic:(NSString*)topic
+                        params:(nullable NSDictionary*)params;
 
 - (PhxPush*)join;
 - (void)leave;
@@ -44,4 +45,6 @@
 
 - (PhxPush*)pushEvent:(NSString*)event payload:(NSDictionary*)payload;
 
-@end
\ No newline at end of file
+@end
+
+NS_ASSUME_NONNULL_END
diff --git a/Pod/Classes/PhxChannel.m b/Pod/Classes/PhxChannel.m
index 3a23158..43ad689 100644
--- a/Pod/Classes/PhxChannel.m
+++ b/Pod/Classes/PhxChannel.m
@@ -12,20 +12,24 @@
 #import "PhxSocket.h"
 #import "PhxSocket_Private.h"
 
+NS_ASSUME_NONNULL_BEGIN
+
 @interface PhxChannel ()
 
-@property (nonatomic, readwrite) ChannelState state;
+@property (nonatomic) ChannelState state;
 
-@property (nonatomic, retain) NSMutableArray *bindings;
+@property (nonatomic, strong) NSMutableArray *bindings;
 
-@property (readwrite) BOOL joinedOnce;
-@property (nonatomic, retain) PhxPush *joinPush;
+@property (atomic) BOOL joinedOnce;
+@property (nonatomic, strong) PhxPush *joinPush;
 
 @end
 
 @implementation PhxChannel
 
-- (id)initWithSocket:(PhxSocket *)socket topic:(NSString *)topic params:(NSDictionary *)params {
+- (instancetype)initWithSocket:(PhxSocket *)socket
+                         topic:(NSString *)topic
+                        params:(nullable NSDictionary *)params {
     self = [super init];
     if (self) {
         self.state = ChannelClosed;
@@ -131,7 +135,7 @@ - (NSString*)replyEventName:(NSString*)ref {
     return [NSString stringWithFormat:@"chan_reply_%@", ref];
 }
 
-- (void)triggerEvent:(NSString*)event message:(id)message ref:(id)ref {
+- (void)triggerEvent:(NSString*)event message:(id)message ref:(nullable id)ref {
     NSPredicate *predicate = [NSPredicate predicateWithBlock:^BOOL(NSDictionary *binding, NSDictionary *bindings) {
         return [[binding valueForKey:@"event"] isEqualToString:event];
     }];
@@ -147,4 +151,8 @@ - (PhxPush*)pushEvent:(NSString*)event payload:(NSDictionary*)payload {
     [pushEvent send];
     return pushEvent;
 }
+
 @end
+
+NS_ASSUME_NONNULL_END
+
diff --git a/Pod/Classes/PhxChannel_Private.h b/Pod/Classes/PhxChannel_Private.h
index 80cd8ee..6ed6b3a 100644
--- a/Pod/Classes/PhxChannel_Private.h
+++ b/Pod/Classes/PhxChannel_Private.h
@@ -8,13 +8,17 @@
 
 #import <Foundation/Foundation.h>
 
+NS_ASSUME_NONNULL_BEGIN
+
 @class PhxChannel;
 
 @interface PhxChannel ()
 
 - (void)rejoin;
-- (void)triggerEvent:(NSString*)event message:(id)message ref:(id)ref;
+- (void)triggerEvent:(NSString*)event message:(id)message ref:(nullable id)ref;
 - (BOOL)isMemberOfTopic:(NSString*)topic;
 - (NSString*)replyEventName:(NSString*)ref;
 
-@end
\ No newline at end of file
+@end
+
+NS_ASSUME_NONNULL_END
diff --git a/Pod/Classes/PhxPush.h b/Pod/Classes/PhxPush.h
index e528f05..22cb7aa 100644
--- a/Pod/Classes/PhxPush.h
+++ b/Pod/Classes/PhxPush.h
@@ -9,17 +9,21 @@
 #import <Foundation/Foundation.h>
 #import "PhxTypes.h"
 
+NS_ASSUME_NONNULL_BEGIN
+
 @class PhxChannel;
 
 @interface PhxPush : NSObject
 
-- (id)initWithChannel:(PhxChannel*)channel
-                event:(NSString*)event
-              payload:(NSDictionary*)payload;
+- (instancetype)initWithChannel:(PhxChannel*)channel
+                          event:(NSString*)event
+                        payload:(NSDictionary*)payload;
 
 - (void)send;
 
-- (PhxPush*)onReceive:(NSString*)status callback:(OnMessage)callback;
-- (PhxPush*)after:(int)ms callback:(After)callback;
+- (PhxPush *)onReceive:(NSString *)status callback:(OnMessage)callback;
+- (PhxPush *)after:(NSTimeInterval)timeInterval callback:(After)callback;
 
 @end
+
+NS_ASSUME_NONNULL_END
\ No newline at end of file
diff --git a/Pod/Classes/PhxPush.m b/Pod/Classes/PhxPush.m
index e35966b..267b91f 100644
--- a/Pod/Classes/PhxPush.m
+++ b/Pod/Classes/PhxPush.m
@@ -11,37 +11,35 @@
 #import "PhxChannel_Private.h"
 #import "PhxSocket.h"
 
+NS_ASSUME_NONNULL_BEGIN
+
 @interface PhxPush ()
 
 @property (nonatomic, weak) PhxChannel *channel;
-@property (nonatomic, retain) NSString *event;
-@property (nonatomic, retain) NSString *refEvent;
-@property (nonatomic, retain) NSDictionary *payload;
+@property (nonatomic, strong) NSString *event;
+@property (nonatomic, strong) NSString *refEvent;
+@property (nonatomic, strong) NSDictionary *payload;
 
-@property (nonatomic, copy) After afterHook;
-@property (readwrite) int afterInterval;
-@property (nonatomic, retain) NSTimer *afterTimer;
+@property (nullable, nonatomic, copy) After afterHook;
+@property (nonatomic) NSTimeInterval afterInterval;
+@property (nullable, nonatomic, strong) NSTimer *afterTimer;
 
-@property (nonatomic, retain) NSMutableArray *recHooks;
-@property (nonatomic, retain) id receivedResp;
-@property (readwrite) BOOL sent;
+@property (nonatomic, strong) NSMutableArray *recHooks;
+@property (nullable, nonatomic, strong) id receivedResp;
+@property (atomic) BOOL sent;
 
 @end
 
 @implementation PhxPush
 
-- (id)initWithChannel:(PhxChannel*)channel
-                event:(NSString*)event
-              payload:(NSDictionary*)payload {
+- (instancetype)initWithChannel:(PhxChannel*)channel
+                          event:(NSString*)event
+                        payload:(NSDictionary*)payload {
     self = [super init];
     if (self) {
         self.channel = channel;
         self.event = event;
-        if (payload) {
-            self.payload = payload;
-        } else {
-            self.payload = @{};
-        }
+        self.payload = payload;
         self.receivedResp = nil;
         self.afterHook = nil;
         self.recHooks = [NSMutableArray new];
@@ -51,7 +49,7 @@ - (id)initWithChannel:(PhxChannel*)channel
 }
 
 - (void)send {
-    const NSString *ref = [self.channel.socket makeRef];
+    NSString *ref = [self.channel.socket makeRef];
     self.refEvent = [self.channel replyEventName:ref];
     self.receivedResp = nil;
     self.sent = NO;
@@ -76,12 +74,16 @@ - (PhxPush*)onReceive:(NSString *)status callback:(OnMessage)callback {
     return self;
 }
 
-- (PhxPush*)after:(int)ms callback:(After)callback {
+- (PhxPush*)after:(NSTimeInterval)timeInterval callback:(After)callback {
     if (self.afterHook) {
         // ERROR
     }
-    self.afterTimer = [NSTimer scheduledTimerWithTimeInterval:ms target:self selector:@selector(afterTimerFire:) userInfo:nil repeats:NO];
-    self.afterInterval = ms;
+    self.afterTimer = [NSTimer scheduledTimerWithTimeInterval:timeInterval
+                                                       target:self
+                                                     selector:@selector(afterTimerFire:)
+                                                     userInfo:nil
+                                                      repeats:NO];
+    self.afterInterval = timeInterval;
     self.afterHook = callback;
     return self;
 }
@@ -129,3 +131,5 @@ - (void)matchReceive:(NSDictionary*)payload {
 }
 
 @end
+
+NS_ASSUME_NONNULL_END
diff --git a/Pod/Classes/PhxPush_Private.h b/Pod/Classes/PhxPush_Private.h
index 492ed0d..28f58de 100644
--- a/Pod/Classes/PhxPush_Private.h
+++ b/Pod/Classes/PhxPush_Private.h
@@ -8,9 +8,12 @@
 
 #import <Foundation/Foundation.h>
 
+NS_ASSUME_NONNULL_BEGIN
 
 @interface PhxPush()
 
-@property (nonatomic, retain) NSDictionary *payload;
+@property (nonatomic, strong) NSDictionary *payload;
 
-@end
\ No newline at end of file
+@end
+
+NS_ASSUME_NONNULL_END
diff --git a/Pod/Classes/PhxSocket.h b/Pod/Classes/PhxSocket.h
index c44eeca..48e819d 100644
--- a/Pod/Classes/PhxSocket.h
+++ b/Pod/Classes/PhxSocket.h
@@ -9,6 +9,8 @@
 #import <Foundation/Foundation.h>
 #import "PhxTypes.h"
 
+NS_ASSUME_NONNULL_BEGIN
+
 @protocol PhxSocketDelegate <NSObject>
 
 - (void)phxSocketDidOpen;
@@ -22,13 +24,13 @@
 @interface PhxSocket : NSObject
 
 @property (nonatomic, weak) id<PhxSocketDelegate> delegate;
-@property (nonatomic, readwrite) BOOL reconnectOnError;
+@property (nonatomic) BOOL reconnectOnError;
 
-- (id)initWithURL:(NSURL*)url;
-- (id)initWithURL:(NSURL*)url heartbeatInterval:(int)interval;
+- (instancetype)initWithURL:(NSURL*)url;
+- (instancetype)initWithURL:(NSURL*)url heartbeatInterval:(NSTimeInterval)interval;
 
 - (void)connect;
-- (void)connectWithParams:(NSDictionary*)params;
+- (void)connectWithParams:(nullable NSDictionary*)params;
 - (void)disconnect;
 - (void)reconnect;
 
@@ -47,3 +49,5 @@
 - (void)push:(NSDictionary*)data;
 
 @end
+
+NS_ASSUME_NONNULL_END
diff --git a/Pod/Classes/PhxSocket.m b/Pod/Classes/PhxSocket.m
index 2578a44..776d6bf 100644
--- a/Pod/Classes/PhxSocket.m
+++ b/Pod/Classes/PhxSocket.m
@@ -13,39 +13,41 @@
 #import "PhxChannel_Private.h"
 #import "NSDictionary+QueryString.h"
 
-static NSTimeInterval reconnectInterval = 5;
+NS_ASSUME_NONNULL_BEGIN
+
+static NSTimeInterval kReconnectInterval = 5;
 
 @interface PhxSocket () <SRWebSocketDelegate>
 
-@property (nonatomic, retain) SRWebSocket *socket;
-@property (nonatomic, retain) NSURL *URL;
-@property (nonatomic, assign) int heartbeatInterval;
+@property (nullable, nonatomic) SRWebSocket *socket;
+@property (nonatomic, strong) NSURL *URL;
+@property (nonatomic) NSTimeInterval heartbeatInterval;
 
-@property (nonatomic, retain) NSMutableArray *channels;
+@property (nonatomic, strong) NSMutableArray *channels;
 @property (nonatomic, strong) NSOperationQueue *queue;
 
-@property (nonatomic, retain) NSTimer *sendBufferTimer;
-@property (nonatomic, retain) NSTimer *reconnectTimer;
-@property (nonatomic, retain) NSTimer *heartbeatTimer;
+@property (nonatomic, strong) NSTimer *sendBufferTimer;
+@property (nullable, nonatomic, strong) NSTimer *reconnectTimer;
+@property (nullable, nonatomic, strong) NSTimer *heartbeatTimer;
 
-@property (nonatomic, retain) NSMutableArray *openCallbacks;
-@property (nonatomic, retain) NSMutableArray *closeCallbacks;
-@property (nonatomic, retain) NSMutableArray *errorCallbacks;
-@property (nonatomic, retain) NSMutableArray *messageCallbacks;
+@property (nonatomic, strong) NSMutableArray *openCallbacks;
+@property (nonatomic, strong) NSMutableArray *closeCallbacks;
+@property (nonatomic, strong) NSMutableArray *errorCallbacks;
+@property (nonatomic, strong) NSMutableArray *messageCallbacks;
 
-@property (nonatomic, retain) NSDictionary *params;
+@property (nullable, nonatomic) NSDictionary *params;
 
-@property (readwrite) int ref;
+@property int ref;
 
 @end
 
 @implementation PhxSocket
 
-- (id)initWithURL:(NSURL*)url {
+- (instancetype)initWithURL:(NSURL*)url {
     return [self initWithURL:url heartbeatInterval:0];
 }
 
-- (id)initWithURL:(NSURL*)url heartbeatInterval:(int)interval {
+- (instancetype)initWithURL:(NSURL*)url heartbeatInterval:(NSTimeInterval)interval {
     self = [super init];
     if (self) {
         self.URL = url;
@@ -70,7 +72,7 @@ - (void)connect {
     [self connectWithParams:nil];
 }
 
-- (void)connectWithParams:(NSDictionary*)params {
+- (void)connectWithParams:(nullable NSDictionary*)params {
     NSURL *url;
     self.params = params;
     if (self.params != nil) {
@@ -211,7 +213,11 @@ - (void)onConnClose:(id)event {
     
     if (self.reconnectOnError) {
         [self discardReconnectTimer];
-        self.reconnectTimer = [NSTimer scheduledTimerWithTimeInterval:reconnectInterval target:self selector:@selector(reconnect) userInfo:nil repeats:YES];
+        self.reconnectTimer = [NSTimer scheduledTimerWithTimeInterval:kReconnectInterval
+                                                               target:self
+                                                             selector:@selector(reconnect)
+                                                             userInfo:nil
+                                                              repeats:YES];
     }
     [self discardHeartbeatTimer];
     
@@ -302,3 +308,5 @@ - (void)webSocket:(SRWebSocket *)webSocket didCloseWithCode:(NSInteger)code reas
 }
 
 @end
+
+NS_ASSUME_NONNULL_END
diff --git a/Pod/Classes/PhxSocket_Private.h b/Pod/Classes/PhxSocket_Private.h
index e60be2e..c1f8744 100644
--- a/Pod/Classes/PhxSocket_Private.h
+++ b/Pod/Classes/PhxSocket_Private.h
@@ -8,7 +8,7 @@
 
 #import <Foundation/Foundation.h>
 
-
+NS_ASSUME_NONNULL_BEGIN
 
 @class PhxSocket;
 @class PhxChannel;
@@ -18,4 +18,6 @@
 - (void)addChannel:(PhxChannel*)channel;
 - (void)removeChannel:(PhxChannel*)channel;
 
-@end
\ No newline at end of file
+@end
+
+NS_ASSUME_NONNULL_END