iOS使用自带的UIViewController实现qq加号下拉菜单的功能(实例代码)

//重置控制器的大小 -(CGSize)preferredContentSize{  if (self.popoverPresentationController != nil) {   CGSize tempSize ;   tempSize.height = self.view.frame.size.height;   tempSize.width = 150;   CGSize size = [_tableVIew sizeThatFits:tempSize];   return size;  }else{   return [super preferredContentSize];  } } 

environmentView.addMenuCallBack = ^(UIButton *sender){   // 设置大小   weakPopView.preferredContentSize = CGSizeMake(120, 150);   // 设置 Sytle   weakPopView.modalPresentationStyle = UIModalPresentationPopover;   // 需要通过 sourceView 来判断位置的   weakPopView.popoverPresentationController.sourceView = sender;   //可以指示小箭头颜色   weakPopView.popoverPresentationController.backgroundColor = [UIColor whiteColor];   // 设置指示箭头的位置   weakPopView.popoverPresentationController.sourceRect = CGRectMake(0, 0, sender.frame.size.width*3/4, sender.frame.size.height);   // 箭头方向   weakPopView.popoverPresentationController.permittedArrowDirections = UIPopoverArrowDirectionUp;   // 设置代理   weakPopView.popoverPresentationController.delegate = weakSelf;   [weakSelf presentViewController:weakPopView animated:YES completion:nil];  };