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Core Data with Mantle
Mantle makes it easy to write a simple model layer for your Cocoa or Cocoa Touch application. Mantle can still be a convenient translation layer between the API and your managed model objects.
本文使用mantle作data model,并使用其对coredata的interface创建数据持久化的过程。
操作过程很简单,就是数据的转换:
1.Manle data model
Mantle中用于持久化的方法:
// A MTLModel object that supports being serialized to and from Core Data as an
// NSManagedObject.
- @protocol MTLManagedObjectSerializing
- @required
// The name of the Core Data entity that the receiver serializes to and
// deserializes from.
- + (NSString *)managedObjectEntityName;
// Specifies how to map property keys to different keys on the receiver‘s
// +managedObjectEntity.
- + (NSDictionary *)managedObjectKeysByPropertyKey;
.h 文件
[objc] view plaincopyprint?
- #import <Foundation/Foundation.h>
- @interface BannerWrapper : MTLModel <MTLJSONSerializing,MTLManagedObjectSerializing>
- @property (nonatomic, readonly) bool result;
- @property (copy, nonatomic, readonly) NSNumber *resultId;
- @property (copy, nonatomic, readonly) NSString *resultMsg;
- @property (copy, nonatomic) NSArray *bannerList;
- +(NSSortDescriptor *)sortDescriptor;
- @end
- @interface Banner : MTLModel <MTLJSONSerializing, MTLManagedObjectSerializing>
- @property (copy, nonatomic, readonly) NSNumber *bannerId;
- @property (copy, nonatomic, readonly) NSString *picUrl;
- @property (copy, nonatomic, readonly) NSString *toDetailUrl;
- @property (copy, nonatomic, readonly) NSNumber *width;
- @property (copy, nonatomic, readonly) NSNumber *height;
- @end
.m文件
[objc] view plaincopyprint?
- #import "Banner.h"
- @implementation BannerWrapper
- #pragma mark - JSON serialization
- + (NSDictionary *)JSONKeyPathsByPropertyKey {
- return @{
- @"result" : @"result",
- @"resultId" : @"resultId",
- @"resultMsg" : @"resultMSG",
- @"bannerList" : @"banner"
- };
- }
- + (NSValueTransformer *)bannerListJSONTransformer
- {
- return [NSValueTransformer mtl_JSONArrayTransformerWithModelClass:[Banner class]];
- }
- #pragma mark - Managed object serialization
- + (NSString *)managedObjectEntityName {
- return @"BannerWrapper";
- }
- + (NSDictionary *)managedObjectKeysByPropertyKey {
- return nil;
- }
- +(NSDictionary *)relationshipModelClassesByPropertyKey{
- return @{
- @"bannerList" : [Banner class],
- };
- }
- //在从coredata中取数据时的数据排序方式
- +(NSSortDescriptor *)sortDescriptor{
- return [[NSSortDescriptor alloc] initWithKey:@"resultId" ascending:YES];
- }
- @end
- @implementation Banner
- #pragma mark - JSON serialization
- + (NSDictionary *)JSONKeyPathsByPropertyKey {
- return @{
- @"bannerId" : @"id",
- @"picUrl" : @"picUrl",
- @"toDetailUrl" : @"toDetailUrl",
- @"width":@"width",
- @"height":@"height"
- };
- }
- #pragma mark - Managed object serialization
- + (NSString *)managedObjectEntityName {
- return @"Banner";
- }
- + (NSDictionary *)managedObjectKeysByPropertyKey {
- return nil;
- }
- @end
2.coredata 持久化类
Coredata主要元素简要介绍
网上有很多图,但,还是觉得一本书上的这个图最好:
- 1, Managed Object Model
Managed Object Model 是描述应用程序的数据模型,这个模型包含实体(Entity),特性(Property),读取请求(Fetch Request)等。(下文都使用英文术语。)
2,Managed Object Context
Managed Object Context 参与对数据对象进行各种操作的全过程,并监测数据对象的变化,以提供对 undo/redo 的支持及更新绑定到数据的 UI。
3,Persistent Store Coordinator
Persistent Store Coordinator 相当于数据文件管理器,处理底层的对数据文件的读取与写入。一般我们无需与它打交道。
4,Managed Object
Managed Object 数据对象,与 Managed Object Context 相关联。
5,Controller
图中绿色的 Array Controller, Object Controller, Tree Controller 这些控制器,一般都是通过 control+drag 将 Managed Object Context 绑定到它们,这样我们就可以在 nib 中可视化地操作数据。
.h文件
[objc] view plaincopyprint?
- #import <Foundation/Foundation.h>
- @interface Persistence : NSObject
- //数据模型对象
- @property(strong,nonatomic) NSManagedObjectModel *managedObjectModel;
- //上下文对象
- @property(strong,nonatomic) NSManagedObjectContext *managedObjectContext;
- //持久性存储区
- @property(strong,nonatomic) NSPersistentStoreCoordinator *persistentStoreCoordinator;
- //确定sqlite文件存储路径
- -(NSURL *)storeURL;
- //初始化Core Data使用的数据库
- -(NSPersistentStoreCoordinator *)persistentStoreCoordinator;
- //managedObjectModel的初始化赋值函数
- -(NSManagedObjectModel *)managedObjectModel;
- //managedObjectContext的初始化赋值函数
- -(NSManagedObjectContext *)managedObjectContext;
- //保存MTLModel对象至coredata
- -(BOOL)saveMTLModel:(MTLModel<MTLManagedObjectSerializing> *)mtlModel
- error:(NSError * __autoreleasing *)error;
- //从coredata中提取出MTLModel
- -(MTLModel *)getMTLmodel:(MTLModel<MTLManagedObjectSerializing> *)mtlModel
- error:(NSError *__autoreleasing *)error;
- //+ (NSFetchRequest *)fetchRequest;
- @end
.m文件
[objc] view plaincopyprint?
- #import "Persistence.h"
- @implementation Persistence
- @synthesize managedObjectContext;
- @synthesize managedObjectModel;
- @synthesize persistentStoreCoordinator;
- //确定sqlite文件存储路径
- -(NSURL *)storeURL{
- //得到数据库的路径
- // NSString *docs = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
- // //CoreData是建立在SQLite之上的,数据库名称需与Xcdatamodel文件同名
- // NSURL *storeUrl = [NSURL fileURLWithPath:[docs stringByAppendingPathComponent:@"CoreData.sqlite"]];
- NSArray *documnetDir=NSSearchPathForDirectoriesInDomains(NSDocumentationDirectory, NSUserDomainMask, YES);
- NSString *docDir=[documnetDir objectAtIndex:0];
- NSString *path=[docDir stringByAppendingPathComponent:@"CoreData.sqlite"];
- NSURL *storeURL=[NSURL fileURLWithPath:path];
- return storeURL;
- }
- //初始化Core Data使用的数据库
- -(NSManagedObjectModel *)managedObjectModel
- {
- if (managedObjectModel != nil) {
- return managedObjectModel;
- }
- return [NSManagedObjectModel mergedModelFromBundles:nil];
- }
- //managedObjectModel的初始化赋值函数
- -(NSPersistentStoreCoordinator *)persistentStoreCoordinator
- {
- if (persistentStoreCoordinator != nil) {
- return persistentStoreCoordinator;
- }
- NSError *error = nil;
- persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc]
- initWithManagedObjectModel:self.managedObjectModel];
- if (![persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType
- configuration:nil
- URL:[self storeURL]
- options:nil
- error:&error]) {
- NSLog(@"Error: %@,%@",error,[error userInfo]);
- [NSException raise:@"open failed" format:@"Reason:%@",[error localizedDescription]];
- }
- return persistentStoreCoordinator;
- }
- //managedObjectContext的初始化赋值函数
- -(NSManagedObjectContext *)managedObjectContext
- {
- if (managedObjectContext != nil) {
- return managedObjectContext;
- }
- NSPersistentStoreCoordinator *coordinator =self.persistentStoreCoordinator;
- if (coordinator != nil) {
- managedObjectContext = [[NSManagedObjectContext alloc]init];
- [managedObjectContext setPersistentStoreCoordinator:coordinator];
- }
- return managedObjectContext;
- }
- //保存MTLModel对象至coredata
- -(BOOL)saveMTLModel:(MTLModel<MTLManagedObjectSerializing> *)mtlModel
- error:(NSError *__autoreleasing *)error{
- //-----Need Add Remove the Entity First START---------
- NSManagedObject *exsitManagedObject=[self getManagedObject:mtlModel
- error:error];
- if (exsitManagedObject!=nil) {
- [self.managedObjectContext deleteObject:exsitManagedObject];
- [self.managedObjectContext save:error];
- };
- //-----Need Add Remove the Entity First END-----------
- NSManagedObject *managedObject = [MTLManagedObjectAdapter
- managedObjectFromModel:mtlModel
- insertingIntoContext:self.managedObjectContext
- error:error];
- if (managedObject==nil) {
- NSLog(@"[NSManagedObject] Error:%@",*error);
- return NO;
- }
- if (![self.managedObjectContext save:error]) {
- NSLog(@"[self.managedObjectContext] Error:%@",*error);
- return NO;
- };
- return YES;
- };
- //从coredata中提取出MTLModel
- -(MTLModel *)getMTLmodel:(MTLModel<MTLManagedObjectSerializing> *)mtlModel
- error:(NSError *__autoreleasing *)error{
- NSManagedObject *managedObject=[self getManagedObject:mtlModel error:error];
- MTLModel *mrlMotel=[[MTLModel alloc] init];
- mrlMotel = [MTLManagedObjectAdapter modelOfClass:[mtlModel class]
- fromManagedObject:managedObject error:error];
- if (error) {
- NSLog(@"[mrlMotel] Error:%@",*error);
- }
- return mrlMotel;
- };
- //从coredata中获取已存的ManagedObject
- -(NSManagedObject *)getManagedObject:(MTLModel<MTLManagedObjectSerializing> *)mtlModel
- error:(NSError *__autoreleasing *)error{
- NSString *entityName=[[mtlModel class] managedObjectEntityName];
- //获取entity中对象数量
- NSFetchRequest *requestCount=[NSFetchRequest fetchRequestWithEntityName:entityName];
- NSUInteger count=[self.managedObjectContext countForFetchRequest:requestCount
- error:error];
- NSLog(@"count result:%d",count);
- NSLog(@"sortDescriptor result:%@",[[mtlModel class] sortDescriptor]);
- //获取entity中第一个对象.这个对象必须存在且唯一。
- if (count==1) {
- NSFetchRequest *request=[[NSFetchRequest alloc] init];
- [request setEntity:[NSEntityDescription entityForName:entityName
- inManagedObjectContext:self.managedObjectContext]];
- NSSortDescriptor *sort=[[mtlModel class] sortDescriptor];
- NSArray *sortDes=[[NSArray alloc] initWithObjects:sort, nil nil];
- [request setSortDescriptors:sortDes];
- NSArray *getObject=[self.managedObjectContext
- executeFetchRequest:request
- error:error];
- return [getObject objectAtIndex:0];
- }
- return nil;
- }
- //从文件系统中删除sqlite文件
- -(bool)deleteAllEntities{
- bool status=NO;
- NSError *error;
- @try{
- [[NSFileManager defaultManager] removeItemAtPath:[self storeURL].path
- error:&error];
- status=YES;
- }
- @catch (NSException *exception) {
- status=NO;
- }
- @finally {
- return status;
- }
- }
- @end
3.后台执行程序
[objc] view plaincopyprint?
- - (void)loadBannerList:(void (^)(NSArray *bannerList, NSError *error))block {
- NSParameterAssert(block);
- [self POST:@"webresources/homePage"
- parameters:nil
- resultClass:BannerWrapper.class
- resultKeyPath:nil
- completion:^(AFHTTPRequestOperation *operation, id responseObject, NSError *error) {
- //-----------------------Persistence DEMO---------------------
- //If network error, get data from CoreData, else save data into CoreData
- if (!error) {
- NSError *err;
- Persistence *persistence=[[Persistence alloc] init];
- BOOL save=[persistence saveMTLModel:responseObject error:&err];
- if (save==NO) {
- NSLog(@"Save ERROR!");
- }
- }else{
- NSError *err;
- Persistence *persistence=[[Persistence alloc] init];
- BannerWrapper *resObject=[[BannerWrapper alloc] init];
- BannerWrapper *object=[[BannerWrapper alloc] init];
- object=[persistence getMTLmodel:resObject error:&err];
- responseObject=object;
- //这个地方异常的奇怪,从coredata中应该返回打Array类型变成了set类型,所以这里暂时作了一个转换。
- if ([object.bannerList isKindOfClass:[NSSet class]]) {
- NSArray *objectArray = [(NSSet *)object.bannerList allObjects];
- ((BannerWrapper *)responseObject).bannerList=objectArray;
- }
- }
- //-----------------------------------------------------------
- BannerWrapper *wrapper = responseObject;
- block(wrapper.bannerList, error);
- }];
- }
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