Fix in-app audio

- sound is set by passing in reference
- don't access properties in constructor
- distinguish multiple variables with same name

// FREEBIE

Signal/src/environment/NotificationsManager.m

@@ -25,15 +25,17 @@
 
 @implementation NotificationsManager
 
-- (instancetype)init {
+- (instancetype)init
+{
     self = [super init];
 
-    if (self) {
-        NSURL *newMessageSound =
-            [NSURL URLWithString:[[NSBundle mainBundle] pathForResource:@"NewMessage" ofType:@"aifc"]];
-        self.newMessageSound = AudioServicesCreateSystemSoundID((__bridge CFURLRef)newMessageSound, &_newMessageSound);
+    if (!self) {
+        return self;
     }
 
+    NSURL *newMessageURL = [[NSBundle mainBundle] URLForResource:@"NewMessage" withExtension:@"aifc"];
+    AudioServicesCreateSystemSoundID((__bridge CFURLRef)newMessageURL, &_newMessageSound);
+
     return self;
 }