Core Data with Mantle(一)

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?
      1. #import
      3. @interface BannerWrapper : MTLModel
      5. @property (nonatomic, readonly) bool result;
      6. @property (copy, nonatomic, readonly) NSNumber *resultId;
      7. @property (copy, nonatomic, readonly) NSString *resultMsg;
      8. @property (copy, nonatomic) NSArray *bannerList;
      9. +(NSSortDescriptor *)sortDescriptor;
      10. @end
      12. @interface Banner : MTLModel
      14. @property (copy, nonatomic, readonly) NSNumber *bannerId;
      15. @property (copy, nonatomic, readonly) NSString *picUrl;
      16. @property (copy, nonatomic, readonly) NSString *toDetailUrl;
      17. @property (copy, nonatomic, readonly) NSNumber *width;
      18. @property (copy, nonatomic, readonly) NSNumber *height;
      20. @end
          
          

          .m文件

          [objc] view plaincopyprint?
          1. #import "Banner.h"
          3. @implementation BannerWrapper
          5. #pragma mark - JSON serialization
          7. + (NSDictionary *)JSONKeyPathsByPropertyKey {
          8. return @{
          9. @"result" : @"result",
          10. @"resultId" : @"resultId",
          11. @"resultMsg" : @"resultMSG",
          12. @"bannerList" : @"banner"
          13. };
          14. }
          16. + (NSValueTransformer *)bannerListJSONTransformer
          17. {
          18. return [NSValueTransformer mtl_JSONArrayTransformerWithModelClass:[Banner class]];
          19. }
          21. #pragma mark - Managed object serialization
          23. + (NSString *)managedObjectEntityName {
          24. return @"BannerWrapper";
          25. }
          27. + (NSDictionary *)managedObjectKeysByPropertyKey {
          28. return nil;
          29. }
          31. +(NSDictionary *)relationshipModelClassesByPropertyKey{
          32. return @{
          33. @"bannerList" : [Banner class],
          34. };
          35. }
          37. //在从coredata中取数据时的数据排序方式
          38. +(NSSortDescriptor *)sortDescriptor{
          39. return [[NSSortDescriptor alloc] initWithKey:@"resultId" ascending:YES];
          40. }
          42. @end
          44. @implementation Banner
          46. #pragma mark - JSON serialization
          48. + (NSDictionary *)JSONKeyPathsByPropertyKey {
          49. return @{
          50. @"bannerId" : @"id",
          51. @"picUrl" : @"picUrl",
          52. @"toDetailUrl" : @"toDetailUrl",
          53. @"width":@"width",
          54. @"height":@"height"
          55. };
          56. }
          58. #pragma mark - Managed object serialization
          60. + (NSString *)managedObjectEntityName {
          61. return @"Banner";
          62. }
          64. + (NSDictionary *)managedObjectKeysByPropertyKey {
          65. return nil;
          66. }
          68. @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