The common pattern for passing information backwards in your view controller hierarchy is to use delegation. You can achieve this in your scenario by implementing the following:
1) Define a protocol in the SearchParametersViewController, which represents your the parent view controller you mentioned.
@protocol SearchParametersViewControllerDelegate <NSObject>
@optional
- (void)searchOptionsSelected:(NSArray *)selectedSearchOptions;
@end
2) Conform to that protocol in your SearchOptionsSelectionViewController, which represents the table view controller that has a list of selections to choose from. Make sure to import or forward-declare the class the protocol is defined in (e.g. SearchParametersViewController) .
#import "SearchParametersViewController.h"
@interface SearchOptionsSelectionViewController <SearchParametersViewControllerDelegate>
3) Define a delegate property in your SearchOptionsSelectionViewController (assumes you are using ARC on iOS 5.0, 4.x use unsafe_unretained instead of weak. Use assign if the project is using manual memory management). This delegate object will contain a reference to your parent view controller (e.g. SearchParametersViewController). You do not want this property to be retained as to avoid retain cycles/circular references where one object references another, which in turn has a reference back to the first and neither object is ever deallocated.
@property (nonatomic, weak) id<SearchParametersViewControllerDelegate> delegate;
4) When instantiating the SearchOptionsSelectionViewController instance inside your parent view controller (SearchParametersViewController), set the delegate property to the parent view controller instance as represented by the self keyword. This ensures you can send the message (and corresponding data) backward in your view controller hierarchy, yet the object relationships remain loosely coupled. This delegate protocol could be conformed to in any other view controller, there are no tight relationships in the selection view controller back to the parent view controller, the only thing linking them is the flexible delegate protocol adoption by the selection view controller.
SearchOptionsSelectionViewController *selectionViewController = [[SearchOptionsSelectionViewController alloc] init];
selectionViewController.delegate = self;
5) Finally, in your SearchOptionsSelectionViewController table view's -tableView:didSelectRowAtIndexPath: delegate method, pass the data corresponding to the selected row back to your parent view controller (SearchParametersViewController) via the delegate method you defined in the SearchParametersViewControllerDelegate protocol. You must use the -respondsToSelector: method to ensure that the delegate object actually implements the -searchOptionsSelected: delegate method. To force this implementation, change @optional to @required above the method prototype in the protocol definition in step #1. self.someDataArray represents a the data source you are using with the selection table view controller. The specifics of the delegate protocol method and data object(s) sent back to the parent view controller can be changed, the important thing here is the delegation pattern and not having any tightly coupled relationships between the instances of either class, but especially backwards in the view controller hierarchy.
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
if ([self.delegate respondsToSelector:@selector(searchOptionsSelected:)])
{
NSArray *selectedObjs = [NSArray arrayWithObject:[self.someDataArray objectAtIndex:indexPath.row]];
[self.delegate searchOptionsSelected:selectedObjs]
}
}
6) Implement the delegate method inside SearchOptionsSelectionViewController.m
- (void)searchOptionsSelected:(NSArray *)selectedSearchOptions
{
// do what you need to with selectedSearchOptions array
}
Further reading:
Cocoa Fundamentals Guide - Delegates and Data Sources
Cocoa Core Competencies - Protocol
