UIAlerView、UIActionSheet 和UIAlertViewController(点击注销确认按钮实现）

 - (IBAction)loginOut:(UIBarButtonItem *)sender {

     UIActionSheet *actionSheet = [[UIActionSheet alloc] initWithTitle:@"确定要退出登陆吗" delegate:self cancelButtonTitle:@"取消" destructiveButtonTitle:@"确定退出" otherButtonTitles:nil];

     [actionSheet showInView:self.view];

 }

 -(void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex{

     if (buttonIndex == ) {

         //退出

         [self.navigationController popViewControllerAnimated:YES];

     }

 }

从IOS8之后，UIAlerView和UIActionSheet 两个合并在了一起，使用了一个新的控制器UIAlertViewController，好处就是不用实现代理

UIActionSheetDelegate和UIAlerViewDelegate

UIAlertViewController使用步骤如下：

//第一步，创建控制器

    UIAlertController *alertVC = [UIAlertController alertControllerWithTitle:@"确定退出吗" message:nil preferredStyle:UIAlertControllerStyleActionSheet];

    //第二步，创建按钮

    UIAlertAction *action1 = [UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleCancel handler:^(UIAlertAction * _Nonnull action) {

        NSLog(@"%s",__func__);

    }];

    UIAlertAction *action2 = [UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleDestructive handler:^(UIAlertAction * _Nonnull action) {

        [self.navigationController popViewControllerAnimated:YES];

    }];

    //第三步，添加按钮

    [alertVC addAction:action1];

    [alertVC addAction:action2];

    //第四步，显示弹窗，相当于show操作

    [self presentViewController:alertVC animated:YES completion:nil];