dispatch_group_t group = dispatch_group_create();
dispatch_group_enter(group);
dispatch_group_async(group, dispatch_get_global_queue(0,0), ^{
dispatch_group_leave(group);
});
dispatch_group_enter(group);
dispatch_group_async(group, dispatch_get_global_queue(0,0), ^{
dispatch_group_leave(group);
});
dispatch_group_notify(group, dispatch_get_global_queue(0,0), ^{
//汇总mode
dispatch_async(dispatch_get_main_queue(), ^{
});
});
