how to pop to different view controller

Question

I have four view controller classes A, B, C, D.

Class D is pushed when the "go" button is pressed from Class A & B.

I have a method in the app delegate which does that for me

-(void)showViewController {
    self.ViewController = [[[ViewController alloc] initWithNibName:@"View"     bundle:nil] autorelease];
    [self.navigationController pushViewController:self.ViewController animated:YES];
}

When the "back" button is pressed from Class D it pops back to either class A & Class B depending on which class pushed Class D

- (void)popViewController {
    [self.navigationController popViewControllerAnimated:YES];
}

What I want to implement is suppose if Class A pushes Class D but when the "back" button is pressed in Class D i want it to go to Class C instead of Class A

I have tried to implement the following code

-(void)popToViewController{
    [self.navigationcontroller popToViewController:self.ClassCViewController animated:YES]
}

This causes changes in Class B which i do not want.

Any Suggestions ?

What about displaying class D using a modalViewController. Then you just need to dismiss it afterwards. — Josiah, Jan 07 '13 at 19:58

score 3 · Accepted Answer · answered Jan 07 '13 at 20:00

So what I would suggest to you is that you take some time and read up on the apple documentation concerning delegates. They will do exactly what you want here where two views can have the same child view. From there have the child view call the delegate to figure out what it needs to do.

Another thing to keep in mind is that it is good practice to have any view that pushes a view to also be the one responsible for popping that view.

EDIT: Just to help you with your original question and get you thinking down the right path. When the back button is pressed in Class D. You would want it to call a method on the delegate (which could be either class A or Class B) from there you could make it go to either the same class. Or if you want to present another view have the delegate view present Class C. Using delegates allows you to have Class A present Class C while allowing Class B to just stay at B when back is pressed. I hope this answers your question.

If you have any further questions about it let me know and I'll try to help in any way I can. — Matt C., Jan 07 '13 at 20:40

score 2 · Answer 2 · answered Jan 07 '13 at 20:06

2

when u pushes ur ViewController in a navigation Controller then all ViewControllers are pushed inside the navigation controller.

find out the viewController from the navigation controller stack and pop to that selected view controller.

Suppose u navigate from A-> B -> C -> D. Then if you normally pop ur view controller from Class D using [self.navigationController popViewControllerAnimated:YES];

then it pops to Class C.

But if you want to pop to Class B or Class A use this:

-(void)popToSelectedViewController
{
  //get all view Controller from Stack of navigation controller
    NSArray *viewControllers=[self.navigationController viewControllers];

  //Declare an Object your selected class
    B  *homeVC=nil;

  //Find out you selected class where u want to pop
    for (int i=0; i<[viewControllers count]; i++)
    {
        UIViewController *tempVC=[viewControllers objectAtIndex:i];
        if([tempVC isKindOfClass:[B class]])
        {
            homeVC=[viewControllers objectAtIndex:i];
            break;
        }
    }


//pop to that selected class if found in stack otherwise popTo RootView
    if(homeVC)
        [self.navigationController popToViewController:homeVC animated:YES];
    else
        [self.navigationController popToRootViewControllerAnimated:YES];

}

I hope this will helps you

answered Jan 07 '13 at 20:06

Satish Azad

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While this will certainly work, it is not good programming style to put a view on the stack that you may never even need. It gets progressively more confusing if you suddenly introduce view E with it's own rules of how to be navigated. Again I want to stress delegates for this matter. It's what they were designed to do. – Matt C. Jan 07 '13 at 20:18
@MechIntel: actually Delegates are used when there is 1-1 interaction of instances. But here the instance is not confirmed. if u use delegate then u need to pass delegate through each class. and i dont think delegate helps for this problem. can u explain how delegate helps to resolve this problem – Satish Azad Jan 07 '13 at 20:23
Delegates are designed specifically not to be used in 1-1 situations. They are designed for this exact scenario. You have two views (A and B) that each push to D. When View D is created the views A and B set themselves as its delegate. Then when D is about to pop it calls its delegate to decide what to do. If A turns out to be D's delegate the code in A will say that it should present view C. If view B is set as D's delegate the code in B will say that it should just stay at B. Then later if you write View E and it also presents D you can have code in E say to present view F. – Matt C. Jan 07 '13 at 20:43
yeah, u r right. I understand what u want to say. thanx man it another good concept for me. :) but the code i have provided, also helps to pop selected viewController if there are more than 4 or 5 ViewControllers. What do u say?? – Satish Azad Jan 07 '13 at 20:47
It will certainly work. You can increase the if to any number of views. My only concern is that it isn't easily extensible especially as you begin to work with more elaborate view hierarchies. You are in essence hard-coding your navigation and making it rigid, which is against what Apple recommends (in this case their recommendations are actually helpful). Delegates allows you to extend your view hierarchy without knowing anything about the hierarchy itself. In my example D doesn't need to know anything about class A or B outside of a predefined protocol that it can guarantee they will resolve – Matt C. Jan 07 '13 at 20:55
Okk... thanxxx. i understand it. :) – Satish Azad Jan 07 '13 at 20:57
To summarize the above comment. It's generally a good idea to write your code so that any view doesn't really care what it's parent view is specifically only that it's parent will be able to handle a specific set of functions that it will define in a protocol and that any view that wishes to present that view must promise to implement. – Matt C. Jan 07 '13 at 20:57

how to pop to different view controller

2 Answers2