How to save nsdictionary of a subview to a mainview based off tableviewcell selection

Question

I am currently parsing some xml that looks like this

&         


        

Answer 1

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

Answer 2

You have a few options, one is to use user defaults. It might be the easiest.

http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSUserDefaults_Class/Reference/Reference.html

Another is to post a notification with the information.

http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/nsnotificationcenter_Class/Reference/Reference.html

Answer 3

You could use the application delegate to achieve your goals here.

I'm going to assume your app has a structure a bit like this. Please excuse the crudity of this model.

Application delegate (A) --> Search Options View (B) --> Table where you do selections (C)
                      |
                      |
                      --> Some other view where you need the selection (D)

Your problem is that you need information to flow from C to D.

Your application delegate has the merit of being universally accessible via [[UIApplication sharedApplication] delegate]. So you can get a pointer to it from anywhere. From C, you can send your selection information back to A. A can either send this on automatically to D, or D can request it from A whenever it wants it.

A couple of points:

• I won't expand any further on my answer at the moment because it's beer o' clock here now, plus I might have misunderstood your requirement. If you do need anything else, I will be up at baby o' clock in the morning UK time so there might be some delay.
• Some people frown on using the application delegate as a "data dump" in the way I have suggested. Some of those people would rather set up a whole singleton class and treat that as a data dump instead. It seems to be one of those neverending arguments so I try not to get involved.