Understanding UISplitViewController and UITableViewController within it

As we navigate through the world of iOS development, one question that often arises is how to manage multiple views and controllers seamlessly. In this article, we’ll delve into the specifics of using UITableViewController as the detail view of a UISplitViewController. This will involve exploring the intricacies of view hierarchy, navigation controllers, and delegates.

The View Hierarchy

To understand the problem at hand, let’s first look at the view hierarchy:

UISplitViewController 
--> 
    UINavigationController 
    --> UITableViewController (DetailViewController)

    UINavigationController
    --> UIViewController (ColorViewController)

Here, we have a UISplitViewController as the root view controller. It has two navigation controllers: one for the detail view (UITableViewController) and another for the master view (UIViewController). The detail view is supposed to be pushed onto the navigation controller of the master view when a cell is selected.

The Problem

The issue here is that when a cell is selected in ColorViewController, it creates a new instance of TableViewController and adds its view to the view controller’s view. This approach seems like a viable solution, but let’s examine why it doesn’t quite work as expected.

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    UIViewController *controller = (UIViewController *)self.splitViewController.delegate;

    TableViewController *tvc = [[TableViewController alloc] init];

    [controller.view addSubview:tvc.view];
}

In this code, we’re essentially trying to force-fit the TableViewController into the view of another UIViewController. However, since UITableViewController is a custom view controller that inherits from UITableViewDataSource and UITableViewDelegate, it doesn’t behave like other view controllers.

The Correct Approach

The correct approach involves using the navigation controller to push the new table view controller. This way, the navigation controller will handle the transition and update the detail view accordingly.

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    UIViewController *controller = self.splitViewController.delegate;

    TableViewController *tvc = [[TableViewController alloc] init];

    [self.splitViewController navigationController].pushViewController(tvc, animated:YES);
}

In this revised code, we’re using the splitViewController to access the navigation controller of the detail view. We then use the pushViewController:animated: method to push the new table view controller onto the navigation stack.

Keeping References to Navigation Controllers

To make this approach more robust, it’s a good idea to keep references to both navigation controllers as properties in the app delegate.

@interface AppDelegate : NSObject

@property (nonatomic, strong) UINavigationController *detailNav;
@property (nonatomic, strong) UINavigationController *masterNav;

@end

By doing so, we can easily access and manipulate these navigation controllers throughout our code.

Moving splitViewController to the App Delegate

Another suggestion from the answer is to move the splitViewController method into the app delegate. This would allow us to keep references to both navigation controllers as properties.

- (UIViewController *) splitViewController {
    // Create the navigation-run root view
    ColorViewController *rootVC = [ColorViewController controller];

    UINavigationController *rootNav = [[UINavigationController alloc] initWithRootViewController:rootVC];

    // Create the navigation-run detail view
    DetailViewController *detailVC = [DetailViewController controller];

    UINavigationController *detailNav = [[UINavigationController alloc] initWithRootViewController:detailVC];

    // Add both to the split view controller
    self.detailNav = rootNav;
    self.masterNav = detailNav;

    return self;
}

By doing so, we can easily access and manipulate these navigation controllers throughout our code.

Conclusion

In conclusion, using UITableViewController as the detail view of a UISplitViewController requires careful consideration of the view hierarchy and navigation controllers. By understanding how to push new table view controllers onto the navigation stack and keeping references to both navigation controllers, we can create a seamless user experience. Remember to move the splitViewController method into the app delegate to make your code more robust and maintainable.

Example Use Case

Here’s an example of how you might use this approach in your code:

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    UIViewController *controller = self.splitViewController.delegate;

    TableViewController *tvc = [[TableViewController alloc] init];

    [self.detailNav pushViewController:tvc animated:YES];
}

In this example, we’re using the detailNav property to push the new table view controller onto the navigation stack.

Tips and Variations

• Make sure to initialize your navigation controllers properly to avoid any issues.
• Consider using a more robust approach to managing your view hierarchy and navigation controllers.
• Don’t forget to update your detail view accordingly when a cell is selected in the master view.

Last modified on 2024-07-21