RestKit学习5：Loading Remote Objects
本系列的前面几篇：
RestKit学习1：引用RestKit项目
RestKit学习2：使用RestKit发送和接受请求
RestKit学习3：CoreData 从模型到实体
RestKit学习4：Database Seeding（生成数据库文件）
这篇是从服务器的一个json接口直接获得数据，并把数据解析成对象。
需要解析的json字符串：
{"error":0,"message":"成功","list":[{"id":1,"name":"传祺","domestic":"国产","logo_ext":"jpg","logo_hash":"4081269f8b182a263b2e881e6c402a5c","seating":5},{"id":2,"name":"传祺GS5","domestic":"国产","logo_ext":"jpg","logo_hash":"b6da2a07ccd3ba7e48e0284524509a64","seating":5},{"id":3,"name":"E系列","domestic":"国产","logo_ext":null,"logo_hash":"d41d8cd98f00b204e9800998ecf8427e","seating":5},{"id":4,"name":"D系列","domestic":"进口","logo_ext":null,"logo_hash":"d41d8cd98f00b204e9800998ecf8427e","seating":3},{"id":5,"name":"V系列","domestic":"国产","logo_ext":null,"logo_hash":"d41d8cd98f00b204e9800998ecf8427e","seating":3}]}
json串对应的实体设置
注意图中的提示，一些保留字不应该出现。
如果中间出现错误：
“*** Assertion failure in -[RKManagedObjectMapping initWithEntity:] Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'The managedObjectClass for an object mapped entity cannot be nil.'”时，解决方法是DataModel.xcdatamodel重新生成一下实体类。
项目的引用看前面的文章。
AppDelegate.m 中Code
定义服务的地址，定义实体类跟json的映射关系
//
// AppDelegate.m
// testRestKit02
//
// Created by cybercare on 12-7-30.
// Copyright (c) 2012年 cybercare. All rights reserved.
//
#import "AppDelegate.h"
#import <RestKit/RestKit.h>
#import <RestKit/CoreData.h>
#define DBNAME @"BAWSeed.sqlite"
@implementation AppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
// Setup the object manager
RKObjectManager* objectManager = [RKObjectManagerobjectManagerWithBaseURLString:@"http://www.in4s.cn:8080/Inpads/android/"];
// 需要存储的文件名
objectManager.objectStore = [RKManagedObjectStoreobjectStoreWithStoreFilename:DBNAME];
// json 文件和 Core Data对象属性映射关系。
RKManagedObjectMapping* mapping = [RKManagedObjectMappingmappingForEntityWithName:@"Series"inManagedObjectStore:objectManager.objectStore];
mapping.primaryKeyAttribute = @"sid";
mapping.rootKeyPath = @"list";
[mapping mapKeyPath:@"id"toAttribute:@"sid"];
[mapping mapKeyPath:@"name"toAttribute:@"sname"];
[mapping mapKeyPath:@"domestic"toAttribute:@"domestic"];
[mapping mapKeyPath:@"logo_ext"toAttribute:@"logo_ext"];
[mapping mapKeyPath:@"logo_hash"toAttribute:@"logo_hash"];
[mapping mapKeyPath:@"seating"toAttribute:@"seating"];
// Register our mappings with the provider
[objectManager.mappingProvidersetObjectMapping:mapping forResourcePathPattern:@"/sync/series"];
#ifdef RESTKIT_GENERATE_SEED_DB
// 需要生成数据库时用
// Load all the data from the file series.json into a seed database
// The seeder will print instructions for how to copy the data to your app
RKManagedObjectSeeder * seeder = [RKManagedObjectSeederobjectSeederWithObjectManager:objectManager];
[seeder seedObjectsFromFile:@"series.json"withObjectMapping:mapping];
[seeder finalizeSeedingAndExit];
#endif
returnYES;
}
- (void)applicationWillResignActive:(UIApplication *)application
{
}
- (void)applicationDidEnterBackground:(UIApplication *)application
{
}
- (void)applicationWillEnterForeground:(UIApplication *)application
{
}
- (void)applicationDidBecomeActive:(UIApplication *)application
{
}
- (void)applicationWillTerminate:(UIApplication *)application
{
}
@end
ViewController.m 中 Code
点击一个按钮是，向服务器的服务发送请求，并获得对象实例。
//
// ViewController.m
// testRestKit02
//
// Created by cybercare on 12-7-30.
// Copyright (c) 2012年 cybercare. All rights reserved.
//
#import "ViewController.h"
#import <RestKit/RestKit.h>
#import "Series.h"
@interfaceViewController ()
@end
@implementation ViewController
- (void)viewDidLoad
{
[superviewDidLoad];
}
- (void)viewDidUnload
{
[superviewDidUnload];
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
}
#pragma mark RKObjectLoaderDelegate methods
- (void)objectLoader:(RKObjectLoader*)objectLoader didLoadObjects:(NSArray*)objects {
NSLog(@"4444" );
if ([objectLoader wasSentToResourcePath:@"/sync/series"]) {
for(Series* item in objects)
{
NSLog(@"%@,%@",item.sid,item.sname);
}
}
}
- (void)objectLoader:(RKObjectLoader*)objectLoader didFailWithError:(NSError*)error {
UIAlertView* alert = [[UIAlertViewalloc] initWithTitle:@"Error"
message:[error localizedDescription]
delegate:nil
cancelButtonTitle:@"OK" otherButtonTitles:nil] ;
[alert show];
NSLog(@"Hit error: %@", error);
NSLog(@"Rats! Failed to load objects: %@", [error localizedDescription]);
}
- (void) ButtonWasPressed:(id)sender {
RKObjectManager * objectManager = [RKObjectManagersharedManager];
[objectManager loadObjectsAtResourcePath:@"/sync/series"delegate:self];
}
@end
这个过程中发生了什么？
1、在 AppDelegate.m 中配置json对象跟实体类的映射关系，在AppDelegate.m中定义是为了重复利用；
2、异步向服务器发送请求 loadObjectsAtResourcePath
3、服务器返回200，以及JSON body
4、RKObjectMapper parsed payload and mapped JSON data to 实体类
5、Callback invoked with array of Contacts
参考资料：
https://github.com/RestKit/RestKit/wiki/Tutorial-%3A-Introduction-to-RestKit