单行宏定义

#define TOKEN [[NSUserDefaults standardUserDefaults] objectForKey:@"USER_TOKEN"]

多行宏定义

#define Login \
    LoginOrRegister *loginOrRegister = [[LoginOrRegister alloc]init]; \
    MainNavVC *nav = [[MainNavVC alloc]initWithRootViewController:loginOrRegister]; \
    nav.modalPresentationStyle = UIModalPresentationOverFullScreen; \
    [self presentViewController:nav animated:YES completion:nil]; \

#define USER_No_Login \
    if (USER_TOKEN) \
    { \
        Login return; \
    } \