cannot jump from switch statement to this case

用switch case出现了一个错误，cannot jump from switch statement to this case....

 查阅资料发现，是因为switch case 中是不能定义对象的，因为只要是在大括号内定义的对象

例如    switch (doBtn.tag) {

        case 107:

       

            NSLog(@"结束");

            

            UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"温馨提示" message:@"确定要结束当前的活动吗" preferredStyle:UIAlertControllerStyleAlert];

            

            UIAlertAction* defaultAction = [UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleDefault

                                                                  handler:^(UIAlertAction * action) {

                                                                      //响应事件

                                                                     [self endActivityRequest];

                                                                  }];

            UIAlertAction* cancelAction = [UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleDefault

                                                                 handler:^(UIAlertAction * action) {

                                                                     //响应事件

                                                                     return ;

                                                                 }];

            [alert addAction:defaultAction];

            [alert addAction:cancelAction];  

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

            

            break;

       

}这样就报错，只要加上一个大括号即可以

    switch (doBtn.tag) {

        case 107:

        {

            NSLog(@"结束");

            

            UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"温馨提示" message:@"确定要结束当前的活动吗" preferredStyle:UIAlertControllerStyleAlert];

            

            UIAlertAction* defaultAction = [UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleDefault

                                                                  handler:^(UIAlertAction * action) {

                                                                      //响应事件

                                                                     [self endActivityRequest];

                                                                  }];

            UIAlertAction* cancelAction = [UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleDefault

                                                                 handler:^(UIAlertAction * action) {

                                                                     //响应事件

                                                                     return ;

                                                                 }];

            [alert addAction:defaultAction];

            [alert addAction:cancelAction];  

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

            

            break;

        }

}