一.CoreData主要的几个类
NSManagedObjectContext
托管对象上下文,进行数据操作时大多都是和这个类打交道。
NSManagedObjectModel
托管对象模型,一个托管对象模型关联一个模型文件(.xcdatamodeld),存储着数据库的数据结构。
NSPersistentStoreCoordinator
持久化存储协调器,负责协调存储区和上下文之间的关系。
NSManagedObject
托管对象类,所有CoreData中的托管对象都必须继承自当前类,根据实体创建托管对象类文件。
二.写一个manage管理类
头文件
@interface QBZCoreDataManage : NSObject
@property (nonatomic, strong) NSManagedObjectContext *managedObjectContext;
@property (nonatomic, strong) NSManagedObjectModel *managedObjectModel;
@property (nonatomic, strong) NSPersistentStoreCoordinator *persistentStoreCoordinator;
+(instancetype)sharedInstance;
//增删改查
//增
- (id)insertObject:(NSString *)type;
//删
- (void)deleteObject:(NSString *)type predicate:(NSPredicate *)predicate;
//改
- (id)changeObject:(NSString *)type predicate:(NSPredicate *)predicate;
//查
- (id)searchObject:(NSString *)type predicate:(NSPredicate *)predicate;
//保存
- (void)saveContext;
@end
实现
+ (instancetype)sharedInstance
{
static id instance = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
instance = [[self alloc] init];
[instance managedObjectContext];
});
return instance;
}
- (NSManagedObjectContext *)managedObjectContext
{
if(!managedObjectContext)
{
managedObjectContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
managedObjectContext.persistentStoreCoordinator = self.persistentStoreCoordinator;
}
return managedObjectContext;
}
- (NSManagedObjectModel *)managedObjectModel
{
if(managedObjectModel == nil){
NSURL *url = [[NSBundle mainBundle] URLForResource:@"QBZCoreData" withExtension:@"momd"];
managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:url];
}
return managedObjectModel;
}
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
if(!persistentStoreCoordinator)
{
persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:self.managedObjectModel];
NSString *dataPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).lastObject;
dataPath = [dataPath stringByAppendingFormat:@"/%@.sqlite", @"QBZCoreData"];
NSLog(@"%@",dataPath);
// NSDictionary *options = {};
[persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:[NSURL fileURLWithPath:dataPath] options:nil error:nil];
}
return persistentStoreCoordinator;
}
- (id)insertObject:(NSString *)type
{
id some = [NSEntityDescription insertNewObjectForEntityForName:type inManagedObjectContext:[QBZCoreDataManage sharedInstance].managedObjectContext];
return some;
}
- (void)deleteObject:(NSString *)type predicate:(NSPredicate *)predicate
{
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:type];
request.predicate = predicate;
NSError *error;
NSArray *reqestArray = [[QBZCoreDataManage sharedInstance].managedObjectContext executeFetchRequest:request error:&error];
[reqestArray enumerateObjectsUsingBlock:^(id _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
[[QBZCoreDataManage sharedInstance].managedObjectContext deleteObject:obj];
}];
}
//改
- (id)changeObject:(NSString *)type predicate:(NSPredicate *)predicate
{
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:type];
request.predicate = predicate;
NSError *error;
NSArray *resultArray = [[QBZCoreDataManage sharedInstance].managedObjectContext executeFetchRequest:request error:&error];
if(resultArray.count>0){
return resultArray[0];
}
return nil;
}
//查
- (id)searchObject:(NSString *)type predicate:(NSPredicate *)predicate
{
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:type];
request.predicate = predicate;
NSError *error;
NSArray *resultArray = [[QBZCoreDataManage sharedInstance].managedObjectContext executeFetchRequest:request error:&error];
return resultArray;
}
- (void)saveContext
{
NSError *error;
if ([QBZCoreDataManage sharedInstance].managedObjectContext.hasChanges) {
[[QBZCoreDataManage sharedInstance].managedObjectContext save:&error];
}
if(error)
{
NSLog(@"CoreData save error:%@",error);
}
}
@end
其他方法见demo