iOS 备忘

添加视图控制器
// add child viewController
    UIViewController* controller =[[UIViewController alloc]init];
    [self addChildViewController:controller];
    controller.view.frame = CGRectMake(0, 44, WIDHT, HEIGHT - 44);
    [self.view addSubview:controller.view];
    [controller didMoveToParentViewController:self];

删除视图控制器
// remove child viewController
    UIViewController *vc = [self.childViewControllers lastObject];
    [vc.view removeFromSuperview];
    [vc removeFromParentViewController];

常用手势
UIPanGestureRecognizer（拖动）

UIPinchGestureRecognizer（捏合）

UIRotationGestureRecognizer（旋转）

UITapGestureRecognizer（点按）

UILongPressGestureRecognizer（长按）

​UISwipeGestureRecognizer（轻扫）

消除最后一根分割线
cell.separatorInset = UIEdgeInsetsMake(0, 0, 0, cell.bounds.size.width);

dispatch_group_t group = dispatch_group_create();
 dispatch_group_async(group, dispatch_get_global_queue(0,0), ^{
      //线程一
 });
 dispatch_group_async(group, dispatch_get_global_queue(0,0), ^{
      // 线程二
 });
 dispatch_group_notify(group, dispatch_get_global_queue(0,0), ^{
    //汇总
 });