How to wait for a thread to finish in Objective-C

Question

I\'m trying to use a method from a class I downloaded somewhere. The method executes in the background while program execution continues. I do not want to allow program exec

Answer 1

Several technical ways to synchronize multi-threads, such as NSConditionLock(mutex-lock), NSCondition(semaphore)。But they are common programming knowledge for other languages(java...) besides objective-c. I prefer to introduce run loop(special in Cocoa) to implement thread join:

NSThread *A; //global
A = [[NSThread alloc] initWithTarget:self selector:@selector(runA) object:nil]; //create thread A
[A start];

- (void)runA    
{
　　[NSThread detachNewThreadSelector:@selector(runB) toTarget:self withObject:nil]; //create thread B    
　　while (1)    
　　{    
　　　　if ([[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]]) //join here, waiting for thread B    
　　　　{    
　　　　　　NSLog(@"thread B quit...");    
　　　　　　break;    
　　　　}    
　　}    
}

- (void)runB    
{    
　　sleep(1);    
　　[self performSelector:@selector(setData) onThread:A withObject:nil waitUntilDone:YES modes:@[NSDefaultRunLoopMode]];    
}