iPhone，後臺線程無法正常工作

我想先顯示視圖，然後在後臺線程中加載數據。當我從根控制器導航到視圖控制器時，我想首先顯示視圖。截至目前，它保持在根控制器上，直到視圖控制器被加載。這是我的根控制器的代碼。iPhone，後臺線程無法正常工作

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath 
{ 
ProductDetailViewController *tempProductDetail = [[ProductDetailViewController alloc] init]; 

[self.navigationController pushViewController:tempProductDetail animated:YES]; 

[tempProductDetail release]; 
}

ProductDetailViewController，在這裏我要首先顯示視圖，然後加載數據...

- (void)viewWillAppear:(BOOL)animated{ 
[super viewWillAppear:YES]; 
[self performSelectorOnMainThread:@selector(workerThread) withObject:nil waitUntilDone:NO]; 
} 

-(void) workerThread{ 

NSAutoreleasePool *arPool = [[NSAutoreleasePool alloc] init]; 
[arPool release]; 
}

不知道我做錯了什麼。請幫忙。

來源

2011-04-27 donito

performSelectorOnMainThread不創建一個新的thread.detachNewThreadSelector將創建一個新的線程。 – rckoenes 2011-04-27 12:43:28

這樣做 \t [NSThread detachNewThreadSelector：@selector（workerThread）toTarget：self withObject：nil]; 顯示我一個錯誤..... bool _WebTryThreadLock（布爾），0x664e200：試圖從主線程或Web線程以外的線程獲取Web鎖。這可能是從輔助線程調用UIKit的結果。現在崩潰... – donito 2011-04-27 13:55:04

發現這個問題的答案，

- (void)viewWillAppear:(BOOL)animated{ 
[super viewWillAppear:YES]; 
[self performSelectorInBackground:@selector(workerThread) withObject:nil]; 
} 

- (void) workerThread 
{ 
// Set up a pool for the background task. 
NSAutoreleasePool* pool = [[NSAutoreleasePool alloc] init]; 

// only do data fetching here, in my case from a webservice. 
//... 

// Always update the components back on the main UI thread. 
[self performSelectorOnMainThread:@selector(displayView) withObject:nil waitUntilDone:YES]; 

[pool release]; 
} 

// Called once the background thread task has finished. 
- (void) displayView 
{ 
//here in this method load all the UI components 
}

來源

2011-04-28 09:27:54 donito

使用[self performSelectorInBackground:@selector(workerThread) withObject:nil];，而不是

[self performSelectorOnMainThread:@selector(workerThread) withObject:nil waitUntilDone:NO];

來源

2011-04-27 12:43:03 PgmFreek

使用這種方法，它告訴我這個錯誤 bool _WebTryThreadLock（布爾），0x6232b10：試圖從主線程或Web線程以外的線程獲取Web鎖。這可能是從輔助線程調用UIKit的結果。立即崩潰... [切換到進程19034] 編程接收信號：「EXC_BAD_ACCESS」。 – donito 2011-04-27 13:45:16

考慮使用以下格式而非用於線程，在我看來，這是更清潔：

- (void)viewWillAppear:(BOOL)animated 
{ 
    NSInvocationOperation *operation = [[NSInvocationOperation alloc] 
             initWithTarget:self 
             selector:@selector(someFunction) 
             object:nil]; 
    [[NSOperationQueue currentQueue] addObject:operation]; // this will actually start the thread 
    [operation release]; 
} 

- (void)someFunction 
{ 
    // don't need to initialize and release an autorelease pool here, 
    // you can just write a function as usual ... 

    [self updateUI]; 
} 

- (void)updateUI 
{ 
    if (![NSThread isMainThread]) // if we need a UI update, force it on main thread 
    { 
     [self performSelectorOnMainThread:@selector(updateUI) withObject:nil waitUntilDone:YES]; 
     return; 
    } 

    // do UI updates here 
}

通過這種方式編寫代碼，您可以更動態地決定因爲沒有自動釋放池的要求，所以你想要線程的功能。如果你需要做UI更新，函數將確保它自己在主線程上運行，所以調用者不需要考慮這一點。

來源

2011-04-27 12:52:20

iPhone，後臺線程無法正常工作

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