1. OC
使用 CoreData 进行数据的持久化
1、CoreData 是一个Cocoa框架，用于存储和管理应用程序中MVC设计模式中模型层数据。对象的持久化表示CoreData框架可以将模型对象保存到持久化文件中。
2、CoreData 框架中包含了FetchRequest数据查询请求、ManagedObjectContent托管对象上下文、PersistentStoreCoordinate持久化存储协调器和PersistentStore持久化存储等概念。
基本概念
- FetchRequest：数据查询请求
- ManagedObjectContent：托管对象上下文
- ManagedObject：托管对象
- PersistentStoreCoordinate：持久化存储协调器
- PersistentStore：持久化存储
CoreData 支持4种类型的持久化存储
1. SQLiteStore
2. XMLStore
3. BinaryStore
4. InMemoryStore
CoreData.jpeg
代码操作
- 创建managedObjectcontext对象
#pragma mark - lazy
- (NSManagedObjectContext *)managedObjectcontext{
if (_managedObjectcontext == nil) {
AppDelegate * appDelegate = (AppDelegate *)[UIApplication sharedApplication].delegate;
_managedObjectcontext = appDelegate.persistentContainer.viewContext;
}
return _managedObjectcontext;
}
- 创建fecthRequest对象
/**
request
创建fecthRequest 获取请求;
NSFetchRequest * fetchRequest = [NSFetchRequest fetchRequestWithEntityName:@"User"];
用语数据查询的偏移位置;
fetchRequest.fetchOffset = 0;
查询的数据总量;
fetchRequest.fetchLimit = 10;
获取托管对象上下文的User实体;
NSEntityDescription * entityDescription = [NSEntityDescription entityForName:@"User" inManagedObjectContext:self.managedObjectcontext];
设置查询条件;
fetchRequest.entity = entityDescription;
@return request
*/
- (NSFetchRequest *)fetchRequest{
if (_fetchRequest == nil) {
_fetchRequest = [NSFetchRequest fetchRequestWithEntityName:@"User"];
_fetchRequest.fetchOffset = 0;
_fetchRequest.fetchLimit = 10;
_fetchRequest.predicate = nil;
_fetchRequest.entity = [NSEntityDescription entityForName:@"User" inManagedObjectContext:self.managedObjectcontext];
}
return _fetchRequest;
}
- 增删改查
#pragma mark - delete-update-save-inquire
- (void)deleteCurrentObject{
NSError *error = nil;
// 发起查询请求并返回查询结果;
NSArray * result = [self.managedObjectcontext executeFetchRequest:self.fetchRequest error:&error];
if (error) {
NSLog(@"删除数据失败--%@",error);
}else{
NSLog(@"删除数据成功");
for (User * user in result) {
[self.managedObjectcontext deleteObject:user];
[self.managedObjectcontext save:&error];
}
}
}
- (void)updateCurrentObject{
// 设置查询条件;
NSPredicate * predicate = [NSPredicate predicateWithFormat:@"userName = 'tongle'"];
self.fetchRequest.predicate = predicate;
NSError *error = nil;
// 发起查询请求并返回查询结果;
NSArray * result = [self.managedObjectcontext executeFetchRequest:self.fetchRequest error:&error];
if (error) {
NSLog(@"更新数据失败--%@",error);
}else{
NSLog(@"更新数据成功");
for (User * user in result) {
user.password = @"11111111";
[self.managedObjectcontext save:&error];
NSLog(@"%@",user.userName);
NSLog(@"%@",user.password);
}
}
}
- (void)inquireCurrentObject{
// 设置查询条件;
NSPredicate * predicate = [NSPredicate predicateWithFormat:@"userName = 'tongle'"];
self.fetchRequest.predicate = predicate;
NSError *error = nil;
// 发起查询请求并返回查询结果;
NSArray * result = [self.managedObjectcontext executeFetchRequest:self.fetchRequest error:&error];
if (error) {
NSLog(@"获取数据失败--%@",error);
}else{
NSLog(@"获取数据成功");
for (User * user in result) {
NSLog(@"%@",user.userName);
NSLog(@"%@",user.password);
}
}
}
- (void)saveCurrentObject{
// 获取Entity对象;
User * user = [NSEntityDescription insertNewObjectForEntityForName:@"User" inManagedObjectContext:self.managedObjectcontext];
user.userName = @"tongle";
user.password = @"123456";
NSError *error = nil;
// 保存;
[self.managedObjectcontext save:&error];
if (error) {
NSLog(@"保存失败--%@",error.userInfo);
} else{
NSLog(@"保存成功");
}
}
</pre>
# 2. Swift
<pre>
func saveCoreData() -> Void {
let appDelegate:AppDelegate = UIApplication.shared.delegate as!AppDelegate
let managed = appDelegate.persistentContainer.viewContext
let newUser = NSEntityDescription.insertNewObject(forEntityName: "Entity", into: managed)as!Entity
newUser.userName = "tongle"
newUser.password = "123456"
do {
try managed.save()
print("保存成功")
} catch {
print("保存失败")
}
}
func deleteCoreData() -> Void {
let appDelegate:AppDelegate = UIApplication.shared.delegate as!AppDelegate
let managed = appDelegate.persistentContainer.viewContext
let entity:NSEntityDescription = NSEntityDescription.entity(forEntityName: "Entity", in: managed)!
let request = NSFetchRequest<Entity>(entityName: "Entity")
request.fetchOffset = 0
request.fetchLimit = 10
request.entity = entity;
let predicate = NSPredicate(format: "userName = 'tongle'")
request.predicate = predicate
do {
print("删除成功")
let results:[AnyObject]? = try managed.fetch(request)
for user:Entity in results as![Entity] {
managed.delete(user)
}
} catch {
print("删除失败")
}
}
func updateCoreData() -> Void {
let appDelegate:AppDelegate = UIApplication.shared.delegate as!AppDelegate
let managed = appDelegate.persistentContainer.viewContext
let entity:NSEntityDescription = NSEntityDescription.entity(forEntityName: "Entity", in: managed)!
let request = NSFetchRequest<Entity>(entityName: "Entity")
request.fetchOffset = 0
request.fetchLimit = 10
request.entity = entity;
let predicate = NSPredicate(format: "userName = 'tongle'")
request.predicate = predicate
do {
print("更新成功")
let results:[AnyObject]? = try managed.fetch(request)
for user:Entity in results as![Entity] {
user.password = "1111111"
try managed.save()
}
} catch {
print("更新失败")
}
}
func inquireCoreData() -> Void {
let appDelegate:AppDelegate = UIApplication.shared.delegate as!AppDelegate
let managed = appDelegate.persistentContainer.viewContext
let entity:NSEntityDescription = NSEntityDescription.entity(forEntityName: "Entity", in: managed)!
let request = NSFetchRequest<Entity>(entityName: "Entity")
request.fetchOffset = 0
request.fetchLimit = 10
request.entity = entity;
let predicate = NSPredicate(format: "userName = 'tongle'")
request.predicate = predicate
do {
print("查询成功")
let results:[AnyObject]? = try managed.fetch(request)
for user:Entity in results as![Entity] {
print("userName = \(String(describing: user.userName))")
print("userName = \(String(describing: user.password))")
}
} catch {
print("查询失败")
}
}
网友评论