List Creation: Creating from a set.

Creating a list based on a set

Instead of using a fetched data controller, sometimes it's nice to take a set or are and display the contents of that array.  This is a reference directly supported by the core data, it reveals items 'related' to your current one in a set.   I was already using this for sight word display and editing.

The goal is to expand my list controller so that I can take in a set, and operate on it.  The usage will be:

- (IBAction) editList:(id) sender

{

JLTableContainer *container=

[JLTableContainer createSetController:nil forList:currentWordList.containedWords

  sortKey:@"wordName"   inContext:[SightWordState Instance].control.managedObjectContext 

controlledBy:nil];

UISelectionMaster * selector=[[UISelectionMaster alloc] init];

selector.listToSelect=container;

[self.navigationController pushViewController:selector animated:true];

}

In this case, I'm just creating a table that displays the 'contained words' set.  The rest of my logic is the same, and I can even decorate it with a selector in the same fashion as my FetchedController table display.  

The implementation is fairly simple given the above:

Initializing the container

First I expand a routine that creates the container, and initializes it.  This needs some refactoring with the other API creation routines, but for now I'll leave it alone.

+ (JLTableContainer*) createSetController:(UITableView *)table

forList:(NSSet *) setToUse

  sortKey:(NSString *) key

  inContext:(NSManagedObjectContext *) context

controlledBy:(NSObject<JLTableController>*) controller

{

JLTableContainer *returnValue=[[JLTableContainer alloc]init];

SimpleDescriptionCellProvider *simpleCellProvider=[[SimpleDescriptionCellProvider alloc] init];

returnValue.table=table;

JLSetSource *source=[[JLSetSource alloc] initWithSet:setToUse sortKey:key];

source.fetchContext=context;

JLStandardCallbackHandler *callHandler=[[JLStandardCallbackHandler alloc]init];

returnValue.tableController=controller;

returnValue.cellProvider=simpleCellProvider;

returnValue.tableSource=source;

returnValue.callbackHandler=callHandler;

[returnValue connectObjects];

return [returnValue autorelease];

}

The header file for the data source

This is the definition of a table source that has a 'set' (converted to a sorted array) as a backing store.  Note that it currently does not support reloading.  This will have to be added.

#import "JLTableControl.h"

@interface JLSetSource : NSObject {

id<JLCellProvider> cellProvider;

NSSet *set;

UITableView *table;

NSArray *currentList;

NSManagedObjectContext *fetchContext;

}

@property (retain,nonatomic) NSSet *set;

@property (retain,nonatomic) NSManagedObjectContext *fetchContext;

@property (retain,nonatomic) NSArray *currentList;

- (JLSetSource *) initWithSet:(NSSet*)set sortKey:(NSString*) sort;

@end

The source for the above

@implementation JLSetSource

@synthesize set;

@synthesize table;

@synthesize cellProvider;

@synthesize currentList;

@synthesize fetchContext;

- (JLSetSource*) initWithSet:(NSSet*)setToUse sortKey:(NSString*) sort

{

self.set=setToUse;

self.currentList=[setToUse getSortedArray:sort];

return self;  

 

}

// Standard section headers.

//- (NSArray *)sectionIndexTitlesForTableView:(UITableView *)tableView {

//    return [[UILocalizedIndexedCollation currentCollation] sectionIndexTitles];

//}

// Get the cell for the current object.  Default to a simple description cell if no actual cell provider is created.

- (UITableViewCell *)tableView:(UITableView *)tableViewb cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    if (self.cellProvider==nil)

self.cellProvider=[[SimpleDescriptionCellProvider alloc] initWithIdentifier:@"GenericQueue"];

NSManagedObject *managedObject=[self.currentList objectAtIndex:indexPath.row];

if (managedObject !=nil)

{

  UITableViewCell *returnValue=[cellProvider cellForObject:managedObject atIndexPath:indexPath forTable:tableViewb];

return returnValue;

}

return nil;

}

- (NSInteger) numberOfSectionsInTableView:(UITableView*) tableView{

return 1;

}

- (id) objectAtIndexPath:(NSIndexPath *) path

{

return [self.currentList objectAtIndex:path.row];

}

// Customize the number of rows in the table view.

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {

return [self.currentList count];

}

All in all its pretty straightforward stuff, but it's nice to have it isolated and implemented once.