Xcode 4核心数据：如何使用在数据模型编辑器中创建的提取属性 [英] Xcode 4 Core Data: How to use fetched property created in Data Model editor

问题描述

如何在Xcode 4中实现获取的属性？

How do you implement a fetched property in Xcode 4?

这里是两个实体，一本书和一个页面的示例：

Here is an example of two entities, a book and a page:

我按照这里的指南创建fetched属性，它使用变量$ FETCH_SOURCE引用源实体的值： http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/CoreData/Articles/cdRelationships.html

I followed the guidelines here to create a fetched property that references a value from the source entity using the variable $FETCH_SOURCE: http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/CoreData/Articles/cdRelationships.html

现在，一旦我保存并生成源代码，我得到：

Now, once I have this saved and I generate the source code I get this:

//  Book.h

#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>

@class Pages;

@interface Book : NSManagedObject {
@private
}
@property (nonatomic, retain) NSString * title;
@property (nonatomic, retain) NSNumber * pageCount;
@property (nonatomic, retain) Pages * pages;

@end

和...

//  Book.m

#import "Book.h"
#import "Pages.h"


@implementation Book
@dynamic title;
@dynamic pageCount;
@dynamic pages;

@end

获取的属性fetchLastPage在哪里？如何在代码中使用它？

Where is the fetched property 'fetchLastPage'? How can I use it in code?

推荐答案

使用 @dynamic 关键字

// In your header
@property (nonatomic, retain) NSArray *fetchLastPage;

// In your class
@dynamic fetchLastPage;

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