uiviewcontroller - 错误切换视图objective-c

Question

当我想从 viewcontroller 切换到 Register.xib 时，我得到一个错误并最终进入 main.m。当我在我的 Register.h 中没有任何变量时它起作用了，但是一旦我添加了一个变量它就不起作用了。

-(IBAction)Register:(UIButton *)sender
{
    //[[NSBundle mainBundle] loadNibNamed:@"Register" owner:self options:nil];
    if(!reg)
    {
        reg = [[Register alloc]initWithNibName:@"Register" bundle:nil];
    }

    UIBarButtonItem *backBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"Back" style:UIBarButtonItemStylePlain target:nil action:nil];
    self.navigationItem.backBarButtonItem = backBarButtonItem;
    [self.navigationController pushViewController:reg animated:YES];

}

当我按下注册按钮时，我在这里结束：

int main(int argc, char *argv[])
{
    @autoreleasepool {
        return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
    }
}