Question

I have a master-detail controller for my app. The master controller is a UITabBarController and each tab is a UITableViewController that contains different types of data.

I plan on having a main header / image on the main detail view but then need to add different subviews to the main detail view to detail specific information depending on which tab I am using.

I am currently adding the relevant subview in my

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath

Function like so:

UIViewController *subview = [[UIViewController alloc] initWithNibName:@"ItemNotFoundViewController" bundle:nil];
subview.view.frame = CGRectMake(20, 160, subview.view.frame.size.width, subview.view.frame.size.height);  
[self.detailViewController.view addSubview:subview.view];

However, I believe that this is a poor way of doing things – every time someone clicks on a table cell another subview will be thrown on top of the stack of previously added subviews, creating memory issues.

What I am wondering is, does ARC take care of this for me? Is my approach passable? and even if it is passable, is there a better way of doing this?

Answer 1

First of all, no. ARC does not take care of this for you. It’s not it’s purpose to do that and even if it was, how could it know, that you don’t want the previously added subviews anymore?
You have to remove those subviews yourself and then ARC will take care of deallocating them (if there are no other references to them).

Anyway that’s not the way you’re supposed to use a UISplitViewController (the master-detail view controller). As you noticed the split view controller handles two other view controllers. The master- and the detailViewController. In most cases the master view controller isn’t changing while the app runs (it’s content changes, but usually that’s handled by a container view controller like UINavigationController which is assigned as the masterViewController), but the detail view controller does.

Instead of adding subviews to your existing detailViewController you should replace it by a new one. So you should create separate XIBs (what you’ve apparently done already) for all the view controllers that you want to present in the detail-section. And modify your code to

self.detailViewController = newDetailViewController; //newDetailViewController would be the vc you called subview in your code

instead of

[self.detailViewController.view addSubview:subview.view];

Edit: Notice that this assumes that your detailViewController property does ‘the right things’ when you set it’s value. By default the UISplitViewController only has a property called viewControllers which is an NSArray in which the first object is the masterVC and the second is the detailVC.

Take a look at MultipleDetailViews for an example of how to manage that.

Since you want to have a header view in all your detail view controllers you have various choice of achieving that (which may or may not be applicable in your case, depending on your design):

• add the header view to every details vc’s XIB
• instead of creating many XIBs for all detailVCs, create a new custom UIViewController subclass that modifies it’s content based on some parameters you give it, i.e. which tableViewCell was tapped by the user
• create a custom container view controller that manages two child view controllers, one for the headline and one for the content above it.

For more information about UISplitViewController and custom container view controller, please refer to:

View Controller Basics

Creating Custom Container View Controllers