(iphone) два executeSelectorInBackground делят один поток?

Question

Когда я несколько раз вызываю executeSelectorInBackground, будет ли задание поставлено в очередь в том же потоке?
так сначала будет выполняться первый и так далее?

Или это будет работать в отдельном потоке?

Спасибо

Answer 1

Новый поток создается при каждом вызове -performSelectorInBackground:withObject:

С http://developer.apple.com/library/ios/#documentation/cocoa/Conceptual/Multithreading/CreatingThreads/CreatingThreads.html#//apple_ref/doc/uid/10000057i-CH15-SW13

Using NSObject to Spawn a Thread

In iOS and Mac OS X v10.5 and later, all objects have the ability to spawn a new thread and use it to execute one of their methods. The performSelectorInBackground:withObject: method creates a new detached thread and uses the specified method as the entry point for the new thread. For example, if you have some object (represented by the variable myObj) and that object has a method called doSomething that you want to run in a background thread, you could could use the following code to do that:

[myObj performSelectorInBackground:@selector(doSomething) withObject:nil];

The effect of calling this method is the same as if you called the detachNewThreadSelector:toTarget:withObject: method of NSThread with the current object, selector, and parameter object as parameters. The new thread is spawned immediately using the default configuration and begins running. Inside the selector, you must configure the thread just as you would any thread. For example, you would need to set up an autorelease pool (if you were not using garbage collection) and configure the thread’s run loop if you planned to use it. For information on how to configure new threads, see “Configuring Thread Attributes.”

Answer 2

Они будут выполнены одновременно, а НЕ один за другим, попробуйте это, чтобы иметь представление:

-(void)prova1{
    for (int i = 1; i<=10000; i++) {
        NSLog(@"prova UNO:%i", i);
    }
}

-(void)prova2{
    for (int i = 1; i<=10000; i++) {
        NSLog(@"_________prova DUE:%i", i);
    }
}

    SEL mioMetodo = NSSelectorFromString(@"prova1");
    [self performSelectorInBackground:mioMetodo withObject:nil];
    SEL mioMetodo2 = NSSelectorFromString(@"prova2");
    [self performSelectorInBackground:mioMetodo2 withObject:nil];

вы получите:

...

_ _ _prova DUE: 795

prova UNO: 798

_ _ _prova DUE: 796

prova UNO: 799

_ _ _prova DUE: 797

prova UNO: 800

_ _ _prova DUE: 798

prova UNO: 801

_ _ _prova DUE: 799

prova UNO: 802

_ _ _prova DUE: 800

prova UNO: 803

_ _ _prova DUE: 801

...

, если вы хотите очередь с 1 методом последругой, попробуйте добавить 2 метода в NSOperationQueue и установите его setMaxConcurrentOperationCount равным 1 ...