MCFetchedResultsViewController.m

//
//  MCFetchedResultsViewController.m
//  MoneyCarta
//
//  Created by Dave Batton on 5/5/15.
//  Copyright (c) 2015 Project Black. All rights reserved.
//

#import "MCFetchedResultsViewController.h"
#import "AppDelegate.h"
#import "UIAlertView+MCAdditions.h"
#import "MCHeaderView.h"


@interface MCFetchedResultsViewController ()

@property (nonatomic) BOOL hasDoneFirstFetch;

@end


@implementation MCFetchedResultsViewController


#pragma mark - Setup & Teardown


- (instancetype)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        _fetchedResultsManagedObjectContext = APPDELEGATE.managedObjectContext;
    }
    return self;
}


- (instancetype)initWithCoder:(NSCoder *)aDecoder
{
    self = [super initWithCoder:aDecoder];
    if (self) {
        _fetchedResultsManagedObjectContext = APPDELEGATE.managedObjectContext;
    }
    return self;
}


- (void)dealloc
{
    _fetchedResultsController.delegate = nil;
    _fetchedResultsController = nil;
    _tableView.delegate = nil;
    _tableView.dataSource = nil;
}


#pragma mark - UIViewController


- (void)viewDidLoad
{
    [super viewDidLoad];

    [self.tableView registerClass:[MCHeaderView class] forHeaderFooterViewReuseIdentifier:@"MCHeaderView"];
    self.hasDoneFirstFetch = NO;
}


- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];

    if (self.hasDoneFirstFetch == NO) {
        [self performFetch];
    }

    [self.tableView deselectRowAtIndexPath:[self.tableView indexPathForSelectedRow] animated:animated];
}


#pragma mark - Public


- (void)performFetch
{
    [UIAlertView mcShowAssert:([self.fetchedResultsEntityName length] > 0) message:@"MCFetchedResultsViewController requires a fetchedResultsEntityName."];
    [UIAlertView mcShowAssert:(self.fetchedResultsSortDescriptors.count > 0) message:@"MCFetchedResultsViewController requires fetchedResultsSortDescriptors."];

    NSError *error;
    [self.fetchedResultsController performFetch:&error];
    [UIAlertView mcShowError:error];
    [self.tableView reloadData];

    self.hasDoneFirstFetch = YES;
}


- (void)configureCell:(UITableViewCell *)cell atIndexPath:(NSIndexPath *)indexPath
{
    // For subclasses to override. No need to call super.
}


- (NSIndexPath *)mapIndexPathFromFetchResultsController:(NSIndexPath *)indexPath
{
    return indexPath;
}


- (NSIndexPath *)mapIndexPathToFetchResultsController:(NSIndexPath *)indexPath
{
    return indexPath;
}


- (NSInteger)mapSectionFromFetchResultsController:(NSInteger)section
{
    return section;
}


- (NSInteger)mapSectionToFetchResultsController:(NSInteger)section
{
    return section;
}


#pragma mark - UITableViewDataSource


- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return self.fetchedResultsController.sections.count;
}


- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
    id<NSFetchedResultsSectionInfo> sectionInfo = self.fetchedResultsController.sections[section];
    return sectionInfo.name;
}


- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    id<NSFetchedResultsSectionInfo> sectionInfo = self.fetchedResultsController.sections[section];
    return sectionInfo.numberOfObjects;
}


#pragma mark - UITableViewDelegate


- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section
{
    return [self.tableView dequeueReusableHeaderFooterViewWithIdentifier:@"MCHeaderView"];
}


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    // Subclass should override. No need to call super.
    return [[UITableViewCell alloc] init];
}


#pragma mark - NSFetchedResultsControllerDelegate


- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller
{
    [self.tableView beginUpdates];
}


- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type
{
    switch(type) {
        case NSFetchedResultsChangeInsert:
            [self.tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex]
                          withRowAnimation:UITableViewRowAnimationFade];
            break;

        case NSFetchedResultsChangeDelete:
            [self.tableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex]
                          withRowAnimation:UITableViewRowAnimationFade];
            break;

        default:
            break;
    }
}


- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath
{
    switch(type) {
        case NSFetchedResultsChangeInsert:
            [self.tableView insertRowsAtIndexPaths:@[newIndexPath]
                                  withRowAnimation:UITableViewRowAnimationFade];
            break;

        case NSFetchedResultsChangeDelete:
            [self.tableView deleteRowsAtIndexPaths:@[indexPath]
                                  withRowAnimation:UITableViewRowAnimationFade];
            break;

        case NSFetchedResultsChangeUpdate:
            [self configureCell:[self.tableView cellForRowAtIndexPath:indexPath] atIndexPath:indexPath];
            break;

        case NSFetchedResultsChangeMove:
            [self.tableView deleteRowsAtIndexPaths:@[indexPath]
                                  withRowAnimation:UITableViewRowAnimationFade];
            [self.tableView insertRowsAtIndexPaths:@[newIndexPath]
                                  withRowAnimation:UITableViewRowAnimationFade];
            break;
    }
}


- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller
{
    [self.tableView endUpdates];
}


#pragma mark - Accessors


- (void)setFetchedResultsEntityName:(NSString *)entityName
{
    [UIAlertView mcShowAssert:(_fetchedResultsController == nil) message:@"You must set fetchedResultsEntityName before the fetchedResultsController has been created."];

    _fetchedResultsEntityName = entityName;
}


- (void)setFetchedResultsPredicate:(NSPredicate *)predicate
{
    [UIAlertView mcShowAssert:(_fetchedResultsController == nil) message:@"You must set fetchedResultsPredicate before the fetchedResultsController has been created. After that, access its fetchRequest property directly."];

    _fetchedResultsPredicate = predicate;
}


- (void)setFetchedResultsSortDescriptors:(NSArray *)sortDescriptors
{
    [UIAlertView mcShowAssert:(_fetchedResultsController == nil) message:@"You must set fetchedResultsSortDescriptors before the fetchedResultsController has been created. After that, access its fetchRequest property directly."];

    _fetchedResultsSortDescriptors = sortDescriptors;
}


- (void)setFetchedResultsSectionNameKeyPath:(NSString *)keyPath
{
    [UIAlertView mcShowAssert:(_fetchedResultsController == nil) message:@"You must set fetchedResultsSectionNameKeyPath before the fetchedResultsController has been created."];

    _fetchedResultsSectionNameKeyPath = keyPath;
}



- (NSFetchedResultsController *)fetchedResultsController
{
    if (_fetchedResultsController != nil) {
        return _fetchedResultsController;
    }

    NSFetchRequest *fetchRequest = [NSFetchRequest fetchRequestWithEntityName:self.fetchedResultsEntityName];
    fetchRequest.predicate = self.fetchedResultsPredicate;
    fetchRequest.sortDescriptors = self.fetchedResultsSortDescriptors;
    _fetchedResultsController = [[NSFetchedResultsController alloc]initWithFetchRequest:fetchRequest
                                                                   managedObjectContext:self.fetchedResultsManagedObjectContext
                                                                     sectionNameKeyPath:self.fetchedResultsSectionNameKeyPath
                                                                              cacheName:nil];
    _fetchedResultsController.delegate = self;
    return _fetchedResultsController;
}


- (void)setFetchedResultsManagedObjectContext:(NSManagedObjectContext *)context
{
    if (_fetchedResultsManagedObjectContext != context) {
        [UIAlertView mcShowAssert:(_fetchedResultsController == nil) message:@"You can't change the managed object context after creating the fetched results controller."];

        _fetchedResultsManagedObjectContext = context;
    }
}


#pragma mark - Actions


- (IBAction)toggleEdit:(id)sender
{
    [self.view endEditing:YES];

    if (self.tableView.isEditing) {
        [APPDELEGATE saveTemporaryContext:self.fetchedResultsController.managedObjectContext];
    }

    UIBarButtonSystemItem systemItem = self.tableView.isEditing ? UIBarButtonSystemItemEdit : UIBarButtonSystemItemDone;
    self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:systemItem
                                                                                          target:self
                                                                                          action:@selector(toggleEdit:)];
    [self.tableView setEditing:!self.tableView.isEditing animated:YES];
}


@end