Fix timer retain cycle.

// FREEBIE

Signal.xcodeproj/project.pbxproj

@@ -61,6 +61,7 @@
 		34B3F89F1E8DF5490035BE1A /* OWSTableViewController.m in Sources */ = {isa = PBXBuildFile; fileRef = 34B3F89E1E8DF5490035BE1A /* OWSTableViewController.m */; };
 		34B3F8A21E8EA6040035BE1A /* ViewControllerUtils.m in Sources */ = {isa = PBXBuildFile; fileRef = 34B3F8A11E8EA6040035BE1A /* ViewControllerUtils.m */; };
 		34D5CC961EA6AFAD005515DB /* OWSContactsSyncing.m in Sources */ = {isa = PBXBuildFile; fileRef = 34D5CC951EA6AFAD005515DB /* OWSContactsSyncing.m */; };
+		34D5CCA61EA934A4005515DB /* NSTimer+OWS.m in Sources */ = {isa = PBXBuildFile; fileRef = 34D5CCA51EA934A4005515DB /* NSTimer+OWS.m */; };
 		34DFCB851E8E04B500053165 /* AddToBlockListViewController.m in Sources */ = {isa = PBXBuildFile; fileRef = 34DFCB841E8E04B500053165 /* AddToBlockListViewController.m */; };
 		34FD93701E3BD43A00109093 /* OWSAnyTouchGestureRecognizer.m in Sources */ = {isa = PBXBuildFile; fileRef = 34FD936F1E3BD43A00109093 /* OWSAnyTouchGestureRecognizer.m */; };
 		450573FE1E78A06D00615BB4 /* OWS103EnableVideoCalling.m in Sources */ = {isa = PBXBuildFile; fileRef = 450573FD1E78A06D00615BB4 /* OWS103EnableVideoCalling.m */; };
@@ -438,6 +439,8 @@
 		34D5CC951EA6AFAD005515DB /* OWSContactsSyncing.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = OWSContactsSyncing.m; sourceTree = "<group>"; };
 		34D5CC981EA6EB79005515DB /* OWSMessageCollectionViewCell.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = OWSMessageCollectionViewCell.h; sourceTree = "<group>"; };
 		34D5CC9B1EA6ED17005515DB /* OWSMessageMediaAdapter.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = OWSMessageMediaAdapter.h; sourceTree = "<group>"; };
+		34D5CCA41EA934A4005515DB /* NSTimer+OWS.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "NSTimer+OWS.h"; sourceTree = "<group>"; };
+		34D5CCA51EA934A4005515DB /* NSTimer+OWS.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = "NSTimer+OWS.m"; sourceTree = "<group>"; };
 		34DFCB831E8E04B400053165 /* AddToBlockListViewController.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = AddToBlockListViewController.h; sourceTree = "<group>"; };
 		34DFCB841E8E04B500053165 /* AddToBlockListViewController.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = AddToBlockListViewController.m; sourceTree = "<group>"; };
 		34FD936E1E3BD43A00109093 /* OWSAnyTouchGestureRecognizer.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = OWSAnyTouchGestureRecognizer.h; path = views/OWSAnyTouchGestureRecognizer.h; sourceTree = "<group>"; };
@@ -1199,6 +1202,8 @@
 				76EB04EB18170B33006006FC /* FunctionalUtil.m */,
 				B62F5E0E1C2980B4000D370C /* NSData+ows_StripToken.h */,
 				B62F5E0F1C2980B4000D370C /* NSData+ows_StripToken.m */,
+				34D5CCA41EA934A4005515DB /* NSTimer+OWS.h */,
+				34D5CCA51EA934A4005515DB /* NSTimer+OWS.m */,
 				76EB04EC18170B33006006FC /* NumberUtil.h */,
 				76EB04ED18170B33006006FC /* NumberUtil.m */,
 				BFB074C519A5611000F2947C /* ObservableValue.h */,
@@ -2057,6 +2062,7 @@
 				34B3F88D1E8DF1700035BE1A /* OWSQRCodeScanningViewController.m in Sources */,
 				34B3F8811E8DF1700035BE1A /* LockInteractionController.m in Sources */,
 				45F659731E1BD99C00444429 /* CallKitCallUIAdaptee.swift in Sources */,
+				34D5CCA61EA934A4005515DB /* NSTimer+OWS.m in Sources */,
 				45BB93381E688E14001E3939 /* UIDevice+featureSupport.swift in Sources */,
 				458DE9D61DEE3FD00071BB03 /* PeerConnectionClient.swift in Sources */,
 				451DE9FD1DC1A28200810E42 /* SyncPushTokensJob.swift in Sources */,

Signal/src/ViewControllers/OWSAudioAttachmentPlayer.m

@@ -3,6 +3,7 @@
 //
 
 #import "OWSAudioAttachmentPlayer.h"
+#import "NSTimer+OWS.h"
 #import "TSAttachment.h"
 #import "TSAttachmentStream.h"
 #import "TSVideoAttachmentAdapter.h"
@@ -117,11 +118,11 @@ NS_ASSUME_NONNULL_BEGIN
 
     [self.audioPlayer prepareToPlay];
     [self.audioPlayer play];
-    self.audioPlayerPoller = [NSTimer scheduledTimerWithTimeInterval:.05
-                                                              target:self
-                                                            selector:@selector(audioPlayerUpdated:)
-                                                            userInfo:nil
-                                                             repeats:YES];
+    self.audioPlayerPoller = [NSTimer weakScheduledTimerWithTimeInterval:.05f
+                                                                  target:self
+                                                                selector:@selector(audioPlayerUpdated:)
+                                                                userInfo:nil
+                                                                 repeats:YES];
 }
 
 - (void)pause

Signal/src/util/NSTimer+OWS.h

@@ -0,0 +1,15 @@
+//
+//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//
+
+@interface NSTimer (OWS)
+
+// This method avoids the classic NSTimer retain cycle bug
+// by using a weak reference to the target.
++ (NSTimer *)weakScheduledTimerWithTimeInterval:(NSTimeInterval)timeInterval
+                                         target:(id)target
+                                       selector:(SEL)selector
+                                       userInfo:(nullable id)userInfo
+                                        repeats:(BOOL)repeats;
+
+@end

Signal/src/util/NSTimer+OWS.m

@@ -0,0 +1,65 @@
+//
+//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//
+
+#import "NSTimer+OWS.h"
+#import <objc/runtime.h>
+
+@interface NSTimerProxy : NSObject
+
+@property (nonatomic, weak) id target;
+@property (nonatomic) SEL selector;
+
+@end
+
+#pragma mark -
+
+@implementation NSTimerProxy
+
+- (void)timerFired:(NSDictionary *)userInfo
+{
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Warc-performSelector-leaks"
+    [self.target performSelector:self.selector withObject:userInfo];
+#pragma clang diagnostic pop
+}
+
+@end
+
+#pragma mark -
+
+static void *kNSTimer_OWS_Proxy = &kNSTimer_OWS_Proxy;
+
+@implementation NSTimer (OWS)
+
+- (NSTimerProxy *)proxy
+{
+    return objc_getAssociatedObject(self, kNSTimer_OWS_Proxy);
+}
+
+- (void)setProxy:(NSTimerProxy *)proxy
+{
+    OWSAssert(proxy);
+
+    objc_setAssociatedObject(self, kNSTimer_OWS_Proxy, proxy, OBJC_ASSOCIATION_RETAIN);
+}
+
++ (NSTimer *)weakScheduledTimerWithTimeInterval:(NSTimeInterval)timeInterval
+                                         target:(id)target
+                                       selector:(SEL)selector
+                                       userInfo:(nullable id)userInfo
+                                        repeats:(BOOL)repeats
+{
+    NSTimerProxy *proxy = [NSTimerProxy new];
+    proxy.target = target;
+    proxy.selector = selector;
+    NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:timeInterval
+                                                      target:proxy
+                                                    selector:@selector(timerFired:)
+                                                    userInfo:userInfo
+                                                     repeats:repeats];
+    [timer setProxy:proxy];
+    return timer;
+}
+
+@end