实现收藏有很多方式，我在自己练习的项目中用CoreData实现了一下收藏功能，注释很少，算是自己做的一个笔记。
首先创建一个工具类继承NSObject,在里面实现所需要的方法.

工具类的.h文件:

<pre>
typedef NS_ENUM(NSUInteger, SelectInEntities) {

InEntities,
NotInEntities,
SelectError,

};

typedef NS_ENUM(NSUInteger, Entities) {

   NewsEntity,
   PostEntity,
  TypeEntity,
  ForumEntity,

};

@interface BFFCoreDataManager : NSObject

// 管理对象上下文(管理者)
@property (readonly, strong, nonatomic) NSManagedObjectContext *managedObjectContext;
// 管理对象模型(表结构)
@property (readonly, strong, nonatomic) NSManagedObjectModel *managedObjectModel;
// 持久化存储协调器(助理)
@property (readonly, strong, nonatomic) NSPersistentStoreCoordinator *persistentStoreCoordinator;
// 保存上下文(保存对数据的修改)

• (void)saveContext;
  // 沙盒路径
• (NSURL *)applicationDocumentsDirectory;

//-(SelectInEntities)isInEntities:(Entities)entities
// Model:(id)model;

+(BFFCoreDataManager *)shareBFFCoreDataManager;

• (id)isInEntities:(Entities)entities model:(id)model;

• (BOOL)has:(NSMutableDictionary *)dic arr:(NSArray *)array;
  ///地方分会
• (BOOL)hass:(NSMutableDictionary *)dic arr:(NSArray *)array;
  ///推荐论坛
• (BOOL)hasss:(BFFDiscussModel *)model arr:(NSArray *)array;
• (BOOL)haspost:(BFFSelectModel *)model arr:(NSArray *)array;
• (BOOL)state:(NSArray *)arr url:(NSString *)url;
• (BOOL)states:(NSArray *)arr ids:(NSString *)ids;

• (id)myModel:(id)model;
  @property (nonatomic, strong) BFFCoreDataManager *manager;
  @end</pre>

工具类的.m文件

<pre>
@implementation BFFCoreDataManager
#pragma mark - Core Data stack

@synthesize managedObjectContext = _managedObjectContext;
@synthesize managedObjectModel = _managedObjectModel;
@synthesize persistentStoreCoordinator = _persistentStoreCoordinator;

• (BFFCoreDataManager *)shareBFFCoreDataManager
  {
  /// 单例不能释放
  static BFFCoreDataManager *manager = nil;
  // 保证线程安全, 该方法只走一次
  static dispatch_once_t onceToken;
  dispatch_once(&onceToken, ^{
  manager = [BFFCoreDataManager new];
  });
  return manager;
  }
  // 获取到沙盒的Document路径

• (NSURL *)applicationDocumentsDirectory {
  // The directory the application uses to store the Core Data store file. This code uses a directory named "com.lanou3g.TheWorldCar" in the application's documents directory.
  return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
  }

• (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:@"TheWorldCar" 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]];
  NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"TheWorldCar.sqlite"];
  NSError *error = nil;
  NSString *failureReason = @"There was an error creating or loading the application's saved data.";

  NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption, [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil];

  if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:options error:&error]) {
  // Report any error we got.
  NSMutableDictionary *dict = [NSMutableDictionary dictionary];
  dict[NSLocalizedDescriptionKey] = @"Failed to initialize the application's saved data";
  dict[NSLocalizedFailureReasonErrorKey] = failureReason;
  dict[NSUnderlyingErrorKey] = error;
  error = [NSError errorWithDomain:@"YOUR_ERROR_DOMAIN" code:9999 userInfo:dict];
  // Replace this with code to handle the error appropriately.
  // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
  NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
  abort();
  }

  return _persistentStoreCoordinator;
  }

• (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;
  }

pragma mark - Core Data Saving support

• (void)saveContext {
  NSManagedObjectContext *managedObjectContext = self.managedObjectContext;
  if (managedObjectContext != nil) {
  NSError *error = nil;
  if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) {
  // Replace this implementation with code to handle the error appropriately.
  // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
  NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
  abort();
  }
  }
  }

• (id)myModel:(id)model{
  NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
  NSEntityDescription *entity = [NSEntityDescription entityForName:@"Type" inManagedObjectContext:self.managedObjectContext];
  [fetchRequest setEntity:entity];
  NSError *error = nil;
  NSArray *fetchedObjects = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
  if (fetchedObjects == nil) {
  NSLog(@"%@", error);
  }
  BFFCollectModel *newsModel = model;
  for (Type *type in fetchedObjects) {
  if ([type.name isEqualToString:newsModel.name]) {
  return type;
  } else {
  return nil;
  }
  }

  return nil;
  }

// 判断是否在数据库中

• (id)isInEntities:(Entities)entities model:(id)model
  {
  switch (entities) {
  case NewsEntity:
  {
  NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
  NSEntityDescription *entity = [NSEntityDescription entityForName:@"News" inManagedObjectContext:self.managedObjectContext];
  [fetchRequest setEntity:entity];
  NSError *error = nil;
  NSArray *fetchedObjects = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
  if (fetchedObjects == nil) {
  NSLog(@"%@", error);
  }
  BFFNewsModel *newsModel = model;
  for (News *news in fetchedObjects) {
  if ([news.newsLink isEqualToString:newsModel.newsLink]) {
  return news;
  }
  }
  return nil;
  }
  break;
  case PostEntity:
  {
  NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
  NSEntityDescription *entity = [NSEntityDescription entityForName:@"Post" inManagedObjectContext:self.managedObjectContext];
  [fetchRequest setEntity:entity];
  NSError *error = nil;
  NSArray *fetchedObjects = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
  if (fetchedObjects == nil) {
  NSLog(@"%@", error);
  }
  BFFHotModel *hot = model;
  for (Post *post in fetchedObjects) {
  if ([post.postLink isEqualToString:hot.postLink]) {
  return post;
  }
  }
  return nil;
  }
  break;
  case TypeEntity:
  {

    }
        break;
    case ForumEntity:
    {
        NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
        NSEntityDescription *entity = [NSEntityDescription entityForName:@"Line" inManagedObjectContext:self.managedObjectContext];
        [fetchRequest setEntity:entity];
        NSError *error = nil;
        NSArray *fetchedObjects = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
        if (fetchedObjects == nil) {
            NSLog(@"%@", error);
        }
        BFFCarDetailModel *carDetail = model;
        for (Line *line in fetchedObjects) {
            if ([line.seriesId isEqualToString:[NSString stringWithFormat:@"%@", carDetail.seriesId]]) {
                return line;
            }
        }
        return nil;
    }
  
        break;
    default:
        break;
  

  }
  return nil;
  }

//爱车俱乐部.人车生活

• (BOOL)has:(NSMutableDictionary *)dic arr:(NSArray *)array{
  NSNumber *num = dic[@"forumId"];
  for (Forum *forum in array) {
  if ([forum.postId isEqualToString:num.description]) {
  return YES;
  }
  }
  return NO;
  }

///地方分会

• (BOOL)hass:(NSMutableDictionary *)dic arr:(NSArray *)array{
  NSNumber *num = dic[@"id"];
  for (Forum *forum in array) {
  if ([forum.postId isEqualToString:num.description]) {
  return YES;
  }
  }
  return NO;
  }

///论坛推荐

• (BOOL)hasss:(BFFDiscussModel *)model arr:(NSArray *)array{
  for (Forum *forum in array) {
  if ([forum.postId isEqualToString:model.forumId.description]) {
  return YES;
  }
  }
  return NO;
  }

///帖子收藏

• (BOOL)haspost:(BFFSelectModel *)model arr:(NSArray *)array{
  for (Post *post in array) {
  if ([post.postLink isEqualToString:model.postLink]) {
  return YES;
  }
  }
  return NO;
  }

///改变帖子收藏按钮图标

• (BOOL)state:(NSArray *)arr url:(NSString *)url{
  for (Post *post in arr) {
  if ([post.postLink isEqualToString:url]) {
  return YES;
  }
  }
  return NO;
  }

///改变论坛收藏按钮图标

• (BOOL)states:(NSArray *)arr ids:(NSString *)ids{
  for (Forum *forum in arr) {
  if ([forum.postId.description isEqualToString:ids]) {
  return YES;
  }
  }
  return NO;
  }

/**-(SelectInEntities)isInEntities:(Entities)entities
Model:(id)model
{
switch (entities) {
case NewsEntity:
{
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"News" inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];
NSError *error = nil;
NSArray *fetchedObjects = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
if (fetchedObjects == nil) {
NSLog(@"%@", error);
}
BFFNewsModel *newsModel = model;

        for (News *news in fetchedObjects) {

            if ([news.newsLink isEqualToString:newsModel.newsLink]) {
                return InEntities;
            } else {
                return NotInEntities;
            }

        }

    }
        break;
        case PostEntity:
    {

   }
        break;
        case LineEntity:
    {

   }
        break;
        case ForumEntity:
    {

    }
       break;
   default:
        break;
}
return SelectError;

}
@end

*/
</pre>

接下来在收藏页面创建一个Button实现收藏

<pre>

• (void)collectionBut:(id)sender{

  BFFCollectModel *model = self.tempModel;
  if ([self.manager myModel:model] == nil) {
  Type *type = [NSEntityDescription insertNewObjectForEntityForName:@"Type" inManagedObjectContext:self.manager.managedObjectContext];
  type.name = model.name;
  type.priceRange = model.priceRange;
  type.photo = model.photo;
  type.uid = [NSString stringWithFormat:@"%@", model.uid];
  [self.manager saveContext];

    self.collectLabel.text = @"已经收藏";
    self.collectLabel.hidden = NO;
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        self.collectLabel.hidden = YES;
    });
  

  } else {
  [self.manager.managedObjectContext deleteObject:[self.manager myModel:model]];
  [self.manager saveContext];
  self.collectLabel.text = @"已取消收藏";
  self.collectLabel.hidden = NO;
  dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
  self.collectLabel.hidden = YES;
  });
  }
  }

///在我的收藏页面把数据取出

• (void)createLineData
  {
  self.typeArr = [NSMutableArray array];
  NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
  NSEntityDescription *entity = [NSEntityDescription entityForName:@"Type" inManagedObjectContext:self.manager.managedObjectContext];
  [fetchRequest setEntity:entity];
  NSError *error = nil;
  NSArray *fetchedObjects = [self.manager.managedObjectContext executeFetchRequest:fetchRequest error:&error];

  if (fetchedObjects == nil) {
  NSLog(@"%@", error);
  }
  [self.typeArr addObjectsFromArray:fetchedObjects];
  [self.tableView reloadData];

}

///这些数据都铺在了tableView上接下来实现删除的操作

• (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
  {
  if (editingStyle == UITableViewCellEditingStyleDelete) {
  if (self.titleSegment.selectedSegmentIndex == 0) {
  News *news = self.newsArr[indexPath.row];
  [self.manager.managedObjectContext deleteObject:news];
  [self.manager saveContext];
  [self.newsArr removeObjectAtIndex:indexPath.row];
  [self.tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationLeft];
  }else if (self.titleSegment.selectedSegmentIndex == 1){
  Post *post = self.postArr[indexPath.row];
  [self.manager.managedObjectContext deleteObject:post];
  [self.manager saveContext];
  [self.postArr removeObjectAtIndex:indexPath.row];
  [self.tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationLeft];
  }else if (self.titleSegment.selectedSegmentIndex == 2){
  Forum *forum = self.forumArr[indexPath.row];
  [self.manager.managedObjectContext deleteObject:forum];
  [self.manager saveContext];
  [self.forumArr removeObjectAtIndex:indexPath.row];
  [self.tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationLeft];

    }else{
    
        Type *type = self.typeArr[indexPath.row];
        [self.manager.managedObjectContext deleteObject:type];
         [self.manager saveContext];
        [self.typeArr removeObjectAtIndex:indexPath.row];
        [self.tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationLeft];
    
    }
  

  }
  [self.tableView reloadData];
  }</pre>

  这些就是实现收藏的过程