NSTimer NSThread

 NSTimer    *timer = [NSTimer scheduledTimerWithTimeInterval:10.0 target:self selector:@selector(UpdateTimerFunc:) userInfo:nil repeats:YES];
        


-(void)UpdateTimerFunc:(NSTimer *)theTimer
{
        
[updateGpsTimer invalidate];//stop timer
        return;
}

NSThread *InitThread = [[NSThread alloc]initWithTarget:self selector:@selector(InitThreadFunc:) object:self];
 [InitThread start];
-(void)InitThreadFunc:(id)sender
{
    ViewController *fSelf = (ViewController*)sender;
    [g_soapReadUserMsgFromSql];
    
    [selfloadWeather];
    
}

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

GCD实现异步

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    // 耗时的操作
    dispatch_async(dispatch_get_main_queue(), ^{
        // 更新界面
    });
});

一组任务

    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    dispatch_group_t group = dispatch_group_create();
    dispatch_group_async(group, queue, ^{
        [NSThread sleepForTimeInterval:1];
        NSLog(@"group1");
    });
    dispatch_group_async(group, queue, ^{
        [NSThread sleepForTimeInterval:2];
        NSLog(@"group2");
    });
    dispatch_group_async(group, queue, ^{
        [NSThread sleepForTimeInterval:3];
        NSLog(@"group3");
    });
    dispatch_group_notify(group, dispatch_get_main_queue(), ^{
        NSLog(@"updateUi");
    });
    dispatch_release(group);