CoreData with Singleton manager - ios

Question

I want to implement Core Data in my app with a Singleton Class that will manage the managed object context. I have the implementation without Core Data because I dont know how to manage everything.
Now, I have this code:
I have my ListViewController:
#interface YPProjectListViewController () {
SelectionSuccessBlock2 successBlock;
}
#property (nonatomic, strong) UITableView *tableView;
#property (nonatomic, strong) NSMutableArray * data;
#property (nonatomic, strong) UIRefreshControl *spinner ;
#end
#implementation YPProjectListViewController
#synthesize tableView;
#synthesize data;
#synthesize spinner;
- (void)viewDidLoad {
[super viewDidLoad];
spinner = [[UIRefreshControl alloc]initWithFrame:CGRectMake(130, 10, 40, 40)];
[self loadProjectsFromService];
[spinner addTarget:self action:#selector(loadProjectsFromService) forControlEvents:UIControlEventValueChanged];
[tableView addSubview:spinner];
}
-(void)loadProjectsFromService{
[spinner beginRefreshing];
self.data = [[NSMutableArray alloc] init];
[self.tableView reloadData];
[self.view addSubview:self.tableView];
__weak typeof(self) weakSelf = self;
successBlock = ^(NSMutableArray *newData) {
if ([newData count] > 0) {
[weakSelf refreshData:newData];
}
};
[spinner endRefreshing];
[ypNetManager getProjectListWithSuccessBlock:successBlock error:NULL];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#pragma mark - Custom getter
- (UITableView *)tableView {
//custom init of the tableview
if (!tableView) {
// regular table view
tableView = [[UITableView alloc] initWithFrame:UIEdgeInsetsInsetRect(self.view.bounds, tableViewInsets) style:UITableViewStylePlain];
tableView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
tableView.delegate = self;
tableView.dataSource = self;
tableView.backgroundColor = [UIColor clearColor];
return tableView;
}
return tableView;
}
#pragma mark - Private methods
- (void)refreshData:(NSMutableArray *)newData {
self.data = newData;
[self.tableView reloadData];
}
I have my AFNetworking AFHttpClient subclass with my method :
- (void)getProjectListWithSuccessBlock:(SelectionSuccessBlock2)success error:(SelectionErrorBlock)error {
NSMutableURLRequest *request = [self requestWithMethod:#"GET" path:kAPIProjectListDev parameters:nil];
[request setTimeoutInterval:kTimeOutRequest];
AFJSONRequestOperation *requestOperation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
// NSLog(#"%# Susscess JSNON Response: %#", NSStringFromSelector(_cmd),JSON);
NSMutableArray * data = [[NSMutableArray alloc] init];
NSDictionary *projects = [JSON valueForKey:kTagProjects];
for (NSDictionary *projectDic in projects) {
[data addObject:[Project createProjectWithDictionary:projectDic]];
}
if (success) {
success(data);
}
}
failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *aError, id JSON) {
NSLog(#"%# Failure JSNON Error%#", NSStringFromSelector(_cmd), aError);
if (error) {
error(aError);
}
}];
[self enqueueHTTPRequestOperation:requestOperation];
}
The object Project :
#property (nonatomic, strong) NSNumber *projectId;
#property (nonatomic, strong) NSString *title;
#property (nonatomic, strong) NSNumber *estimatedPrice;
and its category helper:
#implementation Project (Helper)
+ (Project *)createProjectWithDictionary:(NSDictionary *)dic {
Project *project = [[Project alloc] init];
project.projectId = [NSNumber numberWithInt:[[dic valueForKey:kTagProjectId] intValue]];
project.title = [dic valueForKey:kTagProjectTitle];
project.estimatedPrice = [NSNumber numberWithInt:[[dic valueForKey:kTagProjectEstimatedPrice] floatValue]];
// NSLog(#"Project ..... %d, Title: %#", [project.projectId intValue], project.title);
return project;
}
#end
Now, I want to use my DataSingleton Class to manage my ListViewController and my object projects in a TableView. I have the singleton. but I dont understand quite well where I have to start the managedObjectContext. or where I have to reload the TableView..
//
// DataSingleton.m
// Yeeplys
//
// Created by Carlos Roig Salvador on 8/31/13.
// Copyright (c) 2013 Carlos Roig Salvador. All rights reserved.
//
#import "DataSingleton.h"
//static instance for singleton implementation
static DataSingleton __strong *manager = nil;
//Private instance methods/properties
#interface DataSingleton()
// Returns the managed object context for the application.
// If the context doesn't already exist, it is created and
// bound to the persistent store coordinator for the application.
#property (readonly, strong, nonatomic) NSManagedObjectContext *managedObjectContext;
// Returns the managed object model for the application.
// If the model doesn't already exist, it is created from the application's model.
#property (readonly, strong, nonatomic) NSManagedObjectModel *managedObjectModel;
// Returns the persistent store coordinator for the application.
// If the coordinator doesn't already exist, it is created and the application's
// store added to it.
#property (readonly,strong,nonatomic) NSPersistentStoreCoordinator *persistentStoreCoordinator;
// Returns the URL to the application's Documents directory.
- (NSURL *)applicationDocumentsDirectory;
#end
#implementation DataSingleton
#synthesize managedObjectContext = __managedObjectContext;
#synthesize managedObjectModel = __managedObjectModel;
#synthesize persistentStoreCoordinator = __persistentStoreCoordinator;
//DataAccessLayer singleton instance shared across application
+ (id)sharedInstance
{
#synchronized(self)
{
if (manager == nil)
manager = [[self alloc] init];
}
return manager;
}
+ (void)disposeInstance
{
#synchronized(self)
{
manager = nil;
}
}
+(NSManagedObjectContext *)context
{
return [[DataSingleton sharedInstance] managedObjectContext];
}
//Saves the Data Model onto the DB
- (void)saveContext
{
NSError *error = nil;
NSManagedObjectContext *managedObjectContext = self.managedObjectContext;
if (managedObjectContext != nil)
{
if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error])
{
//Need to come up with a better error management here.
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
}
}
// Returns the managed object context for the application.
// If the context doesn't already exist, it is created and
// bound to the persistent store coordinator for the application.
- (NSManagedObjectContext *)managedObjectContext
{
if (__managedObjectContext != nil)
return __managedObjectContext;
NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
if (coordinator != nil)
{
__managedObjectContext = [[NSManagedObjectContext alloc] init];
[__managedObjectContext setPersistentStoreCoordinator:coordinator];
}
return __managedObjectContext;
}
// Returns the managed object model for the application.
// If the model doesn't already exist, it is created from the
// application's model.
- (NSManagedObjectModel *)managedObjectModel
{
if (__managedObjectModel != nil)
return __managedObjectModel;
NSURL *modelURL = [[NSBundle mainBundle] URLForResource:#"yeeplyModel"
withExtension:#"momd"];
__managedObjectModel = [[NSManagedObjectModel alloc]
initWithContentsOfURL:modelURL];
return __managedObjectModel;
}
// Returns the persistent store coordinator for the application.
// If the coordinator doesn't already exist, it is created and the
// application's store added to it.
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
if (__persistentStoreCoordinator != nil)
return __persistentStoreCoordinator;
NSURL *storeURL = [[self applicationDocumentsDirectory]
URLByAppendingPathComponent:#"MyData.sqlite"];
NSError *error = nil;
__persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc]
initWithManagedObjectModel:[self managedObjectModel]];
if (![__persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType
configuration:nil URL:storeURL options:nil error:&error])
{
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
return __persistentStoreCoordinator;
}
// Returns the URL to the application's Documents directory.
- (NSURL *)applicationDocumentsDirectory
{
return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory
inDomains:NSUserDomainMask] lastObject];
}
#end

Answer 1

To reload your table view you can attach an NSFetchedResultsController (link to Apple docs) to your view controller in order to get automatic updates every time you update your NSManagedObjectContext. There is a code in this repository made by Javi Soto that is easy to understand in order to implement the NSFetchedResultsController in your project. Take a look at JSBaseCoreDataTableViewController here.