队列数组，并行执行1

dispatch_queue_t dispatchQueue = dispatch_queue_create("baipeng.queue.com", DISPATCH_QUEUE_CONCURRENT);
dispatch_group_t dispatchGroup = dispatch_group_create();
dispatch_group_async(dispatchGroup, dispatchQueue, ^(){
    NSLog(@"任务一完成");
 });
dispatch_group_async(dispatchGroup, dispatchQueue, ^(){
    NSLog(@"任务二完成");
 });
dispatch_group_async(dispatchGroup, dispatchQueue, ^(){
    NSLog(@"任务三完成");

});
dispatch_group_async(dispatchGroup, dispatchQueue, ^(){
    NSLog(@"任务四完成");

});
dispatch_group_notify(dispatchGroup, dispatch_get_main_queue(), ^(){
    NSLog(@"notify：任务都完成了");



});