iOS开发学习之Core Data
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1.添加DataModel文件
2.添加实体和属性
@interface AppDelegate ()
@property (nonatomic,strong) NSManagedObjectContext *managedObjectContext;
@property (nonatomic,strong) NSManagedObjectModel *managedObjectModel;
@property (nonatomic,strong) NSPersistentStoreCoordinator *persistentStoreCoordinator;
@end
5.在AppDelegate.m文件的@implementation底部添加以下代码：
#pragma mark - Core Data
-(NSManagedObjectModel *)managedObjectModel
{
if(_managedObjectModel == nil)
{
NSString *modelPath = [[NSBundle mainBundle] pathForResource:@"DataModel" ofType:@"momd"];
NSURL *modelURL = [NSURL fileURLWithPath:modelPath];
_managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
}
return _managedObjectModel;
}
-(NSString *)documentsDirectory
{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths lastObject];
//NSLog(@"%@",documentsDirectory);
return documentsDirectory;
}
-(NSString *)dataStorePath
{
return [[self documentsDirectory] stringByAppendingPathComponent:@"DataStore.sqlite"];
}
-(NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
if(_persistentStoreCoordinator == nil)
{
NSURL *storeURL = [NSURL fileURLWithPath:[self dataStorePath]];
_persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:self.managedObjectModel];
NSError *error;
if(![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error])
{
NSLog(@"Error adding persistent store %@,%@",error,[error userInfo]);
abort();
}
}
return _persistentStoreCoordinator;
}
-(NSManagedObjectContext *)managedObjectContext
{
if(_managedObjectContext == nil)
{
NSPersistentStoreCoordinator *coordinator = self.persistentStoreCoordinator;
if(coordinator != nil)
{
_managedObjectContext = [[NSManagedObjectContext alloc] init];
[_managedObjectContext setPersistentStoreCoordinator:coordinator];
}
}
return _managedObjectContext;
}
6.在需要应用Core Data进行数据操控的视图控制器的.h头文件中添加以下代码：
@property (nonatomic,strong) NSManagedObjectContext *managedObjectContext;
7.在AppDelegate.m文件中分别#import以上视图控制器的.h文件，并将AppDelegate创建的managedObjectContext的指针传递给以上控制器
如：
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// Override point for customization after application launch.
UITabBarController *tabBarController = (UITabBarController *)self.window.rootViewController;
CurrentLocationViewController *currentLocationViewController = (CurrentLocationViewController *)tabBarController.viewControllers[0];
currentLocationViewController.managedObjectContext = self.managedObjectContext;//传递指针
UINavigationController *navigationController = (UINavigationController *)tabBarController.viewControllers[1];
LocationsViewController *locationsViewController = (LocationsViewController *)navigationController.viewControllers[0];
locationsViewController.managedObjectContext = self.managedObjectContext;//传递指针
MapViewController *mapViewController = (MapViewController *)tabBarController.viewControllers[2];
mapViewController.managedObjectContext = self.managedObjectContext;//传递指针
return YES;
}
当以上视图控制器切换到其他需要应用Core Data操控数据的视图控制器时，可通过prepareForSegue将managedObjectContext的指针传递过去
如：
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if([segue.identifier isEqualToString:@"TagLocation"])
{
UINavigationController *navigationController = segue.destinationViewController;
LocationDetailsViewController *controller = (LocationDetailsViewController *)navigationController.topViewController;
controller.coordinate = _location.coordinate;
controller.placemark = _placemark;
controller.managedObjectContext = self.managedObjectContext;//传递指针
}
}
（1）添加数据：
（2）修改数据：
（3）删除数据：
（4）查找数据：
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