Add some nullability annotations (#62)

* fix compiler warnings about info message initializers

// FREEBIE

SignalServiceKit.podspec

@@ -8,7 +8,7 @@
 
 Pod::Spec.new do |s|
   s.name             = "SignalServiceKit"
-  s.version          = "0.5.2"
+  s.version          = "0.5.3"
   s.summary          = "An Objective-C library for communicating with the Signal messaging service."
 
   s.description      = <<-DESC

src/Messages/Interactions/TSInfoMessage.h

@@ -1,13 +1,10 @@
-//
-//  TSInfoMessage.h
-//  TextSecureKit
-//
 //  Created by Frederic Jacobs on 15/11/14.
 //  Copyright (c) 2014 Open Whisper Systems. All rights reserved.
-//
 
 #import "TSMessage.h"
 
+NS_ASSUME_NONNULL_BEGIN
+
 @interface TSInfoMessage : TSMessage
 
 typedef NS_ENUM(NSInteger, TSInfoMessageType) {
@@ -25,6 +22,8 @@ typedef NS_ENUM(NSInteger, TSInfoMessageType) {
 @property TSInfoMessageType messageType;
 @property NSString *customMessage;
 
+- (instancetype)initWithCoder:(NSCoder *)coder NS_DESIGNATED_INITIALIZER;
+
 - (instancetype)initWithTimestamp:(uint64_t)timestamp
                          inThread:(TSThread *)contact
                       messageType:(TSInfoMessageType)infoMessage NS_DESIGNATED_INITIALIZER;
@@ -32,6 +31,15 @@ typedef NS_ENUM(NSInteger, TSInfoMessageType) {
 - (instancetype)initWithTimestamp:(uint64_t)timestamp
                          inThread:(TSThread *)thread
                       messageType:(TSInfoMessageType)infoMessage
-                    customMessage:(NSString *)customMessage NS_DESIGNATED_INITIALIZER;
+                    customMessage:(NSString *)customMessage;
+
+- (instancetype)initWithTimestamp:(uint64_t)timestamp
+                         inThread:(nullable TSThread *)thread
+                      messageBody:(nullable NSString *)body
+                    attachmentIds:(NSArray<NSString *> *)attachmentIds
+                 expiresInSeconds:(uint32_t)expiresInSeconds
+                  expireStartedAt:(uint64_t)expireStartedAt NS_UNAVAILABLE;
 
 @end
+
+NS_ASSUME_NONNULL_END

src/Messages/Interactions/TSInfoMessage.m

@@ -1,21 +1,28 @@
-//
-//  TSInfoMessage.m
-//  TextSecureKit
-//
 //  Created by Frederic Jacobs on 15/11/14.
 //  Copyright (c) 2014 Open Whisper Systems. All rights reserved.
-//
 
 #import "NSDate+millisecondTimeStamp.h"
 #import "TSInfoMessage.h"
 
+NS_ASSUME_NONNULL_BEGIN
+
 @implementation TSInfoMessage
 
+- (instancetype)initWithCoder:(NSCoder *)coder
+{
+    return [super initWithCoder:coder];
+}
+
 - (instancetype)initWithTimestamp:(uint64_t)timestamp
                          inThread:(TSThread *)thread
                       messageType:(TSInfoMessageType)infoMessage
 {
-    self = [super initWithTimestamp:timestamp inThread:thread];
+    self = [super initWithTimestamp:timestamp
+                           inThread:thread
+                        messageBody:nil
+                      attachmentIds:@[]
+                   expiresInSeconds:0
+                    expireStartedAt:0];
 
     if (!self) {
         return self;
@@ -64,3 +71,5 @@
 }
 
 @end
+
+NS_ASSUME_NONNULL_END

src/Security/OWSFingerprintBuilder.m

@@ -31,7 +31,7 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (OWSFingerprint *)fingerprintWithTheirSignalId:(NSString *)theirSignalId
 {
-    NSData *theirIdentityKey = [self.storageManager identityKeyForRecipientId:theirSignalId];
+    NSData *_Nullable theirIdentityKey = [self.storageManager identityKeyForRecipientId:theirSignalId];
 
     return [self fingerprintWithTheirSignalId:theirSignalId theirIdentityKey:theirIdentityKey];
 }