coredata 封装

可以作为工具类来封装

#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>

@interface CoredataManager : NSObject

@property (nonatomic) NSManagedObjectContext* managedObjectContext;
@property (nonatomic) NSPersistentStoreCoordinator *persistentStoreCoordinator;
@property (nonatomic) NSManagedObjectModel *managedObjectModel;

+ (CoredataManager *)shareInstance;
- (void)save;

@end

#import "CoredataManager.h"

@implementation CoredataManager

+ (CoredataManager *)shareInstance {
    static CoredataManager *manager = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        manager = [[CoredataManager alloc] init];
    });
    return manager;
}

- (NSManagedObjectContext *)managedObjectContext {
    // Returns the managed object context for the application (which is already bound to the persistent store coordinator for the application.)
    if (_managedObjectContext != nil) {
        return _managedObjectContext;
    }
    
    NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
    if (!coordinator) {
        return nil;
    }
    _managedObjectContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
    [_managedObjectContext setPersistentStoreCoordinator:coordinator];
    return _managedObjectContext;
}

- (NSManagedObjectModel *)managedObjectModel {
    // The managed object model for the application. It is a fatal error for the application not to be able to find and load its model.
    if (_managedObjectModel != nil) {
        return _managedObjectModel;
    }
    NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"CoredataSample" withExtension:@"momd"];
    _managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
    return _managedObjectModel;
}

- (NSPersistentStoreCoordinator *)persistentStoreCoordinator {
    // The persistent store coordinator for the application. This implementation creates and returns a coordinator, having added the store for the application to it.
    if (_persistentStoreCoordinator != nil) {
        return _persistentStoreCoordinator;
    }
    
    // Create the coordinator and store
    _persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
    
    //database auto upgrade support
    NSDictionary *options = @{
                              NSMigratePersistentStoresAutomaticallyOption : @YES,
                              NSInferMappingModelAutomaticallyOption : @YES
                              };
    
    NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"CoredataSample.sqlite"];
    NSError *error = nil;
    if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:options error:&error]) {
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        abort();
    }
    return _persistentStoreCoordinator;
}

- (NSURL *)applicationDocumentsDirectory {
    // The directory the application uses to store the Core Data store file. This code uses a directory named "lisaliu.com.CoredataSample" in the application's documents directory.
    return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}

- (void)save {
    NSError *error;
    if (![_managedObjectContext save:&error]) {
        NSLog(@"save datas failed!");
    } else {
        NSLog(@"save datas succed!");
    }
}