Create a new ViewController object only if it doesnt exist

Question

I use the following code to bring up a view

-(IBAction) openSomeView{
SomeView *sv = [[SomeView alloc]initWithNibName:@"SomeView" bundle:nil];
[self presentModalViewController:sv animated:NO];
[sv release];

}

How can I detect if this view has been created already and if so, then just show it now create a new object?

Thanks

Answer 1

You cannot create more than one instance using this code, since you present modally the view controller.

Else, you'd probably keep a member variable in your class and check it against nil.

EDIT: or you can implement the 'Singleton' design pattern, if that's the meaning you search.

Answer 2

I have a couple of heavy-weight view controllers in my app. Right now I'm handling this situation as follows:

• save MyViewController to appDelegate

• in "openSomeView" method I'm checking if MyViewController was already created, if no - create it:

  -(IBAction) openSomeView {
      MyAppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
  
  
      if ( !appDelegate.myViewController ) {
          appDelegate.myViewController = [[SomeViewController alloc] initWithNibName:@"SomeViewController" 
                                                                              bundle:nil];
      }
  
  
      [self presentModalViewController:appDelegate.myViewController animated:NO];
  }
  
  
  

Answer 3

first declare in @interface

SomeView *sv; 

and the you can check it

-(IBAction) openSomeView{
if(sv==nil)
sv = [[SomeView alloc]initWithNibName:@"SomeView" bundle:nil];
[self presentModalViewController:sv animated:NO];
[sv release];
}