如何使iOS UIViewController成为singleton？

我有两个

UIViewController

，RootViewController和SecondViewController

SecondViewController连接到服务器，现在我返回到RootViewController（

UINavigationController

），但当我从

RootViewController

转到SecondViewController时，有一个新的SecondViewController

我怎样才能使用旧的SecondViewController

---

我使用了singleton，但当我返回到RootViewController时，我不能再次转到SecondViewController

应该有一个MainViewController，在MainViewController内部，您应该初始化RootViewController（或ServerViewController）和SecondViewController

当你点击后退按钮时，一个视图应该是隐藏的。如果您可以共享代码，请参阅更多。

AppDelegate.h

@property (strong, nonatomic) UIViewController *sc;

AppDelegate.m

_sc = nil;

RootViewController.m

- (IBAction)tiaozhuian:(UIButton *)sender {
    AppDelegate *appDelegate=[[UIApplication sharedApplication] delegate];
    if(appDelegate.sc == nil)
    {
      appDelegate.sc=[self.storyboard instantiateViewControllerWithIdentifier:@"SecondViewController"];
      [self.navigationController pushViewController:appDelegate.sc animated:YES];
      NSLog(@"%@",appDelegate.sc);
    } else {
      [self.navigationController pushViewController:appDelegate.sc animated:YES];
    }
}

定义一个全局变量sc，sc=nil，sc=appDelegate.sc=

[self.storyboard实例化eviewcontrollerwhiteIdentifier:@“SecondViewController”]

当第一次转到SecondView时，返回RootView并再次转到SecondView，无论sc是否为零，如果不是，则转到SecondView

AppDelegate.h
@property (strong, nonatomic) UIViewController *sc;
AppDelegate.m
_sc = nil;
RootViewController.m
- (IBAction)tiaozhuian:(UIButton *)sender {
    AppDelegate *appDelegate=[[UIApplication sharedApplication] delegate];
    if(appDelegate.sc == nil)
    {
    appDelegate.sc=[self.storyboard instantiateViewControllerWithIdentifier:@"SecondViewController"];
    [self.navigationController pushViewController:appDelegate.sc animated:YES];
    NSLog(@"%@",appDelegate.sc);
    }else{
    [self.navigationController pushViewController:appDelegate.sc animated:YES];
    }
}

---

//定义一个全局变量sc，sc=nil，sc=appDelegate.sc=[self.storyboard instanceeviewcontrollerwhiteIdentifier:@“SecondViewController”]当第一次转到SecondView时，无论sc是否为nil，都返回RootView并再次转到SecondView，如果不是，则转到SecondView。

不要为此使用单例。这是一个糟糕的主意。您应该创建一些帮助器类来实现这一点，就像rmaddy说的：不要为此使用单例！是否有演示？如果我使用helper类，如何连接到UIViewController？helper类是singleton？不要只是发布代码。解释你的答案是如何解决问题的。

AppDelegate.h
@property (strong, nonatomic) UIViewController *sc;
AppDelegate.m
_sc = nil;
RootViewController.m
- (IBAction)tiaozhuian:(UIButton *)sender {
    AppDelegate *appDelegate=[[UIApplication sharedApplication] delegate];
    if(appDelegate.sc == nil)
    {
    appDelegate.sc=[self.storyboard instantiateViewControllerWithIdentifier:@"SecondViewController"];
    [self.navigationController pushViewController:appDelegate.sc animated:YES];
    NSLog(@"%@",appDelegate.sc);
    }else{
    [self.navigationController pushViewController:appDelegate.sc animated:YES];
    }
}