GKSession displayNameForPeer阻止释放会话(iOS 4.0，4.1)

Question

在为另一个对等体（而不是自己）调用displayNameForPeer后，我可以在发布GKSession时可靠地使模拟器崩溃，我不确定这是我做错了什么，还是苹果Gamekit框架的错误（我是否需要担心，因为我只在4.0和4.1下看到崩溃，而不是4.2+）。

输出为：

found available peer; checking name and ID... m4, 26176566
*** -[GKSessionInternal lock]: message sent to deallocated instance 0x7508900

这是可重复的最小代码集——请注意，另一个GKSession必须在网络上可见（这样就可以找到一个可用的对等点来调用displayNameForPeer）来触发崩溃。在另一台设备上运行相同的代码，但不使用makeUnavailable和killSession调用就足够了。

- (void)viewDidLoad
{
[self createSession];
[self makeAvailable];
peerListAvailable = [[NSMutableArray alloc] initWithArray:[currentSession peersWithConnectionState:GKPeerStateAvailable]];
for (NSString *peer in peerListAvailable)
{
    // this method guarantees the crash on session release
    NSLog(@"found available peer; checking name and ID... %@, %@",[currentSession displayNameForPeer:peer], peer);
}
[peerListAvailable release];
peerListAvailable = nil;

[self makeUnavailable];
[self killSession];
[super viewDidLoad];
}

- (void) createSession
{
if (!currentSession)
{
    currentSession = [[GKSession alloc] initWithSessionID:@"GKTester" displayName:nil sessionMode:GKSessionModePeer];
    currentSession.delegate = self;
    currentSession.disconnectTimeout = 30;
    [currentSession setDataReceiveHandler: self withContext:nil];
}
}
-(void) killSession
{
if (currentSession) 
{
    [currentSession disconnectFromAllPeers];
    [currentSession setDelegate:nil];
    [currentSession setDataReceiveHandler:nil withContext:nil];
    [currentSession release]; // crash occurs after this
    currentSession = nil;   
}
}
-(void) makeAvailable
{
while (currentSession && !currentSession.available)
{
    [currentSession setAvailable:YES];
    [NSThread sleepForTimeInterval:.5];
}
}
-(void) makeUnavailable
{
while (currentSession && currentSession.available)
{
    [NSThread sleepForTimeInterval:.5];
    [currentSession setAvailable:NO];
}

}

Answer 1

您的代码中存在过度发布：

[currentSession disconnectFromAllPeers];
[currentSession setDelegate:nil];
[currentSession setDataReceiveHandler:nil withContext:nil];
[currentSession release]; // This is an over-release
currentSession = nil; // You are trying to access a variable after it's been released

您应该只在dealloc中释放currentSession成员变量，如下所示：

- (void)dealloc
{
    [currentSession release];
    [super dealloc];
}