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我有一个 NSOperation 在我使用的 -main 方法中[NSThread detachNewThreadSelector:@selector(aMethod:) toTarget:self withObject:anArgument];

aObject（我的 NSOperation 子类的实例变量）是对在 -main 方法内返回的自动释放数组的对象的弱引用... 

-(void)main {

    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

    NSArray *clients = [group produceClients]; // clients array is an autorelease instance
    self->aObject = [clients objectAtIndex:3]; // a weak reference, Lets say at index three!

    [NSThread detachNewThreadSelector:@selector(aMethod:) 
                             toTarget:self 
                           withObject:@"I use this for another thing"];

    // Do other things here that may take some time

    [pool release];
}

-(void)aMethod:(NSString*)aStr {

    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

    // aStr object is reserved for another functionality
    // I know that I could pass a NSDictionary with a number of entries, which would be
    // retained by `detachNewThreadSelector` but then ... 
    // I wouldn't have to ask this question ! :)

    // Do several things with aObject, which is a weak reference as described above.
    NSLog(@"%@", [self->aObject.id]);
    // Is it safe ?

    [pool release];
}

我知道 NSThread 的 detachNewThreadSelector 方法保留self和 withObject: anArgument，但是 aObject 会发生什么？是否确定在执行分离线程（aMethod:) 期间会存在？自我被保留detachNewThreadSelector，这是否意味着-主线程的池将被延迟释放，因为它被保留，因此clients将存在，因此aObject将存在？
或者-main（NSOperation）线程将在-aMethod（NSThread）完成之前完成执行并释放，所以在aObject那里使用不安全？

真正的问题是：当从线程内部调用[NSThread detachNewThreadSelector:@selector(aMethod:) ...toTarget:self ...]时，最后一个线程是否被保留，其自动释放的实例（clients数组）可以安全地在aMethod( self->aObject) 中使用（让我们说通过弱引用）？

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1 回答 1

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您的方法似乎非常不稳定，但我不是多线程专家，所以我可能是错的。您的客户端数组位于主自动释放池中，您不能保证会等到您的 aMethod 线程完成耗尽。那这个呢：

-(void)main {

    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

    [NSThread detachNewThreadSelector:@selector(aMethod:) 
                             toTarget:self 
                           withObject:@"I use this for another thing"];

    [pool release];
}

-(void)aMethod:(NSString*)aStr {

    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

    NSArray *clients = [group produceClients]; // clients array is an autorelease instance
    self->aObject = [clients objectAtIndex:3]; // a weak reference, Lets say at index three!

    [pool release];
}

使用这种方法，您的客户端数组位于线程的自动释放池中。

于 2011-06-04T01:00:01.003 回答