pcwiki的部落格

.h

#import <CoreData/CoreData.h>

@property (nonatomic, strong, readonly) NSManagedObjectModel *managedObjectModel;

@property (nonatomic, strong, readonly) NSManagedObjectContext *managedObjectContext;

@property (nonatomic, strong, readonly) NSPersistentStoreCoordinator *persistentStoreCoordinator;

- (NSURL *)applicationDocumentsDirectory; // nice to have to reference files for core data

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.m

@synthesize managedObjectContext = _managedObjectContext;

@synthesize managedObjectModel = _managedObjectModel;

@synthesize persistentStoreCoordinator = _persistentStoreCoordinator;

- (void)saveContext{

    NSError *error = nil;

    NSManagedObjectContext *managedObjectContext = self.managedObjectContext;

    if (managedObjectContext != nil) {

        if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) {

            NSLog(@"Unresolved error %@, %@", error, [error userInfo]);

            abort();

        }

    }

}

- (NSManagedObjectContext *)managedObjectContext{

    if (_managedObjectContext != nil) {

        return_managedObjectContext;

    }

    NSPersistentStoreCoordinator *coordinator = [selfpersistentStoreCoordinator];

    if (coordinator != nil) {

        _managedObjectContext = [[NSManagedObjectContextalloc] init];

        [_managedObjectContextsetPersistentStoreCoordinator:coordinator];

    }

    return_managedObjectContext;

}

- (NSManagedObjectModel *)managedObjectModel{

    if (_managedObjectModel != nil) {

        return_managedObjectModel;

    }

    NSURL *modelURL = [[NSBundlemainBundle] URLForResource:@"Rank"withExtension:@"momd"];

    _managedObjectModel = [[NSManagedObjectModelalloc] initWithContentsOfURL:modelURL];

    return_managedObjectModel;

}

- (NSPersistentStoreCoordinator *)persistentStoreCoordinator

{

    if (_persistentStoreCoordinator != nil) {

        return_persistentStoreCoordinator;

    }

    NSURL *storeURL = [[selfapplicationDocumentsDirectory] URLByAppendingPathComponent:@"Rank.sqlite"];

    NSError *error = nil;

    _persistentStoreCoordinator = [[NSPersistentStoreCoordinatoralloc] initWithManagedObjectModel:[selfmanagedObjectModel]];

    if (![_persistentStoreCoordinatoraddPersistentStoreWithType:NSSQLiteStoreTypeconfiguration:nilURL:storeURL options:nilerror:&error]) {

        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);

        abort();

    }

    return_persistentStoreCoordinator;

}

#pragma mark - Application's Documents directory

// Returns the URL to the application's Documents directory.

- (NSURL *)applicationDocumentsDirectory{

    return [[[NSFileManagerdefaultManager] URLsForDirectory:NSDocumentDirectoryinDomains:NSUserDomainMask] lastObject];

}

---------------------

.h

#import <Foundation/Foundation.h>

#import <CoreData/CoreData.h>

@interface DatabaseManager : NSObject

+ (id)sharedInstance;

-(void)insertWithName:(NSString*)name withScore:(int)score;

-(NSArray*)load;

@property (nonatomic,strong) NSManagedObjectContext* managedObjectContext;

@end

----------------

.m

#import "DatabaseManager.h"

staticDatabaseManager* instance;

@implementation DatabaseManager

+ (id)sharedInstance {

    staticdispatch_once_t onceToken;

    dispatch_once(&onceToken, ^{

        instance = [selfnew];

    });

    returninstance;

}

-(NSManagedObjectContext *)managedObjectContext{

    NSManagedObjectContext* context = nil;

    id delegate = [[UIApplicationsharedApplication] delegate];

    if([delegate performSelector:@selector(managedObjectContext)]){

        context = [delegate managedObjectContext];

    }

    return context;

}

-(void)insertWithName:(NSString*)name withScore:(int)score{

    NSManagedObjectContext* context = [selfmanagedObjectContext];

    NSManagedObject* entity = [NSEntityDescriptioninsertNewObjectForEntityForName:@"Entity"inManagedObjectContext:context];

    [entity setValue:name forKey:@"name"];

    [entity setValue:[NSNumbernumberWithInt:score] forKey:@"score"];

    NSError *error;

    if (![context save:&error]) {

        NSLog(@"Whoops, couldn't save: %@", [error localizedDescription]);

    }

}

-(NSArray*)load{

    NSManagedObjectContext* context = [selfmanagedObjectContext];

    NSFetchRequest *fetchRequest = [[NSFetchRequestalloc] init];

    NSEntityDescription *entity = [NSEntityDescription

                                   entityForName:@"Entity"inManagedObjectContext:context];

    NSSortDescriptor *sortByScore = [NSSortDescriptorsortDescriptorWithKey:@"score"ascending:NO];

    [fetchRequest setEntity:entity];

    [fetchRequest setSortDescriptors:@[sortByScore]];

    NSError *error;

    NSArray *fetchedObjects = [context executeFetchRequest:fetchRequest error:&error];

    return fetchedObjects;

}

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