Interface Builder IB - 导航控制器，跳过视图

Question

Hello I am new to iOS and have a question about navigating through my views.

I am using IB wiring up the PREVIOUS and NEXT buttons in the nav bar that pushes my views. This all works fine. However I am having trouble finding out where exactly what I need to do or where I need to place the code so I can skip over a view. To simplify my situation...

-I have 1 Nav Controller and 4 View Controllers named VC1, VC2, VC3, VC4. Each VC has a .H/.M -Starting from VC1, they follow one after the other.

Say I want to skip VC3 and jump right to VC4 based on a setting in VC2. Where would I put the code to do this? Would I need to unhook the IBAction method from the NAV buttons at VC3?

I do apologize if this has been covered before. If there is a tut or if you know of a post that answers this, please let me know. I did do a search but the search was returning generic posts probably due to me using the wrong terminology.

Thanks in advance.

Answer 1

A couple of thoughts:

1. If you want to push from VC2 to either VC3 or to VC4, rather than having VC3 immediately push to VC4 in special cases, I think it's better to just have VC2 push directly to the appropriate view controller. Thus you might have an IBAction in VC2 that would do this for you:

    - (IBAction)pushToNext:(id)sender { BOOL skipToVC4 = ... // put in whatever logic you'd use to bypass VC3 and go directly to VC4 UIViewController *nextController; if (skipToVC4) { nextController = [self.storyboard instantiateViewControllerWithIdentifier:@"VC4"]; // obviously, if using NIBs, you'd do something like: // nextController = [[ViewController4 alloc] initWithNibName:@"VC4" bundle:nil]; } else { nextController = [self.storyboard instantiateViewControllerWithIdentifier:@"VC3"]; } [self.navigationController pushViewController:nextController animated:YES]; } 

   This way, when you pop back from VC4, you'll pop back directly to the appropriate view controller (eg if you pushed from VC2 to VC4, when you pop, you'll pop right back to VC2 automatically.

   And, obviously, if you're using storyboards, rather than manually invoking pushViewController , you could have two segues from VC2 (one to VC3 and one to VC4), give them appropriate identifiers, and then just invoke performSegueWithIdentifier to segue to the appropriate view controller. But the idea is the same: You can define an IBAction that performs the appropriate segue depending upon whatever logic you so choose.

2. You say that you have "PREVIOUS and NEXT buttons in the nav bar that pushes my views", I wonder about your "PREVIOUS" button. Is that doing a popViewControllerAnimated ? Generally, a "NEXT" button will push to a new view controller, but the "PREVIOUS" button should not push to the previous view, but pop back to it. If you don't pop back, you can end up with multiple instances of some of your prior view controllers. Thus, the "PREVIOUS" button should be linked to an IBOutlet that does something like:

    - (IBAction)popToPrevious:(id)sender { [self.navigationController popViewControllerAnimated:YES]; } 

3. When popping back, you'll obviously pop back to the view controller that you pushed from. If you want to skip a few of the view controllers as you're popping back in iOS versions prior to 6.0, you would use popToViewController or popToRootViewControllerAnimated . For example, let's say that you pushed from VC1 to VC2, to VC3, to VC4. If you want to pop back from VC4 all the way to VC1, you would hook up and IBAction in VC4 like:

    - (IBAction)popToRoot:(id)sender { [self.navigationController popToRootViewControllerAnimated:YES]; } 

   Or, if you wanted to pop back from VC4 to VC2, you would

    - (IBAction)popToVC2:(id)sender { for (UIViewController *controller in self.navigationController.viewControllers) { if ([controller isKindOfClass:[ViewController2 class]]) { [self.navigationController popToViewController:controller animated:YES]; return; } } } 

   You can avoid this iteration through the navigationController.viewControllers if you passed a reference of VC2 to VC3 and then again to VC4, but sometimes the above technique is easier.

   By the way, if you're supporting iOS 6 and above, only, and are using storyboards, you can also use unwind segues, which are a more elegant way of popping back to a particular view controller. But it's not clear whether (a) you're using storyboards; and (b) you're supporting iOS 6 and above only, so I'll refrain from a discussion of unwind segues at this point.

Answer 2

First:
Show us some code, where you are pushing new view controllers, maybe your whole navigation controller code

Second (Solution) :

I assume:

• Your prev/next buttons are linked to your navigationController class
• you have the appropriate methods (prevPressed:/nextPressed:), which are called, when you click one of the buttons

I can help you with the following:

• you know which controller is visible at the moment with the visibleViewController @property
• each time you click on a button in the navBar you can ask the visibleViewController which next/previous view controller should be pushed/popped

Best solution would be, if all of your controllers VC1/2/3/4 are a subclass of a viewController class, which defines a method in it's interface:

- (Class)nextViewControllerClass;
- (Class)previousViewControllerClass;

and in the implementation:

- (Class)nextViewControllerClass {
    return [VC4 class];
}

- (Class)previousViewControllerClass {
    return [VC1 class];
}

And in your navigationController code the do this:

- (IBAction)next:(id)sender {
    UIViewController *nextViewController = [[[self.visibleViewController nextViewControllerClass] alloc] init];
    [self pushViewController:nextViewController animated:YES];
}