NSThread与_NSAutoreleaseNoPool错误

Question

我有一种方法可以将文件保存到互联网上,它可以工作但速度很慢.然后我想让用户界面更加流畅,所以我创建了一个NSThread来处理缓慢的任务.

我看到一个错误列表,如:

_NSAutoreleaseNoPool(): Object 0x18a140 of class NSCFString autoreleased with no pool in place - just leaking

没有NSThread,我称之为:

[self save:self.savedImg];

我使用以下内容使用NSThread来调用方法:

NSThread* thread1 = [[NSThread alloc] initWithTarget:self
                                        selector:@selector(save:)
                                              object:self.savedImg];
[thread1 start];

谢谢.

Answer 1

首先,您要为保存代码创建一个新线程,然后异步使用NSUrlConnection.NSUrlConnection在它自己​​的实现中也会分拆另一个线程并在你新创建的线程上回调,这主要不是你想要做的事情.我假设您只是想确保在保存时UI不会阻塞...

NSUrlConnection也有同步版本,它将阻塞你的线程,如果你想启动你自己的线程做事情,最好使用它.签名是

+ sendSynchronousRequest:returningResponse:error:

然后,当您收到响应时,您可以回调您的UI线程.下面的东西应该工作:

- (void) beginSaving {
   // This is your UI thread. Call this API from your UI.
   // Below spins of another thread for the selector "save"
   [NSThread detachNewThreadSelector:@selector(save:) toTarget:self withObject:nil];    

}

- (void) save {
   NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];  

   // ... calculate your post request...
   // Initialize your NSUrlResponse and NSError

   NSUrlConnection *conn = [NSUrlConnection sendSyncronousRequest:postRequest:&response error:&error];
   // Above statement blocks until you get the response, but you are in another thread so you 
   // are not blocking UI.   

   // I am assuming you have a delegate with selector saveCommitted to be called back on the
   // UI thread.
   if ( [delegate_ respondsToSelector:@selector(saveCommitted)] ) {
    // Make sure you are calling back your UI on the UI thread as below:
    [delegate_ performSelectorOnMainThread:@selector(saveCommitted) withObject:nil waitUntilDone:NO];
   }

   [pool release];
}

Answer 2

您需要主要为线程创建自动释放池.尝试将保存方法更改为:

- (void) save:(id)arg {
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

    //Existing code

    [pool drain];
}

你不会认为上述内容不会在NSAutoreleasePool上调用release.这是一个特例.对于NSAutoreleasePool,相当于在没有GC的情况下运行时释放,并转换为收集器的提示,可能是运行集合的好点.