RestKit iOS應用程序的在線和離線支持

Question

我想爲需要在離線和離線狀態下工作的應用程序使用RestKit。

我可能會誤解RestKit的工作方式，但我認爲這是相當容易實現的。

在劃痕試驗iOS應用餘設置的東西，如下：根據需要CoreData支持

// setup the client 
NSString* URL = @"http://10.211.55.5:3000/api"; 
RKClient* client = [RKClient clientWithBaseURL:URL]; 
client.username = @"me@email.com"; 
client.password = @"password"; 

// setup caching 
client.cachePolicy = RKRequestCachePolicyLoadIfOffline | RKRequestCachePolicyLoadOnError | RKRequestCachePolicyTimeout; 
client.requestCache.storagePolicy = RKRequestCacheStoragePolicyPermanently; 

// setup managed object store 
RKObjectManager* objectManager = [RKObjectManager objectManagerWithBaseURL:URL]; 
RKManagedObjectStore* objectStore = [RKManagedObjectStore objectStoreWithStoreFilename:@"RestKitCoreDataTest.sqlite"]; 

// connect my cache implementation 
MyCache* cache = [[MyCache alloc] init]; 
objectStore.managedObjectCache = cache; 
objectManager.objectStore = objectStore; 

// setup mapping  
RKManagedObjectMapping* userMapping = [RKManagedObjectMapping mappingForClass:[User class]]; 
[userMapping mapKeyPath:@"id" toAttribute:@"identifier"]; 
[userMapping mapKeyPath:@"email" toAttribute:@"email"]; 
[userMapping mapKeyPath:@"firstname" toAttribute:@"firstname"]; 
[userMapping mapKeyPath:@"surname" toAttribute:@"surname"]; 
userMapping.primaryKeyAttribute = @"identifier"; 
[objectManager.mappingProvider setMapping:userMapping forKeyPath:@""]; 

// setup routes 
RKObjectRouter* router = [objectManager router]; 
[router routeClass:[User class] toResourcePath:@"https://stackoverflow.com/users/:identifier"]; 

用戶對象被實現：

@interface User : NSManagedObject 

@property (nonatomic, retain) NSNumber * identifier; 
@property (nonatomic, retain) NSString * email; 
@property (nonatomic, retain) NSString * firstname; 
@property (nonatomic, retain) NSString * surname; 

@end 

@implementation User 

@dynamic identifier; 
@dynamic email; 
@dynamic firstname; 
@dynamic surname; 

@end 

這裏是MyCache。請注意，我並不打算檢查resourcePath，因爲這僅僅用於試用，而且我有一條路徑。

@implementation MyCache 
- (NSArray*)fetchRequestsForResourcePath:(NSString*)resourcePath 
{ 
    NSFetchRequest* fetchRequest = [User fetchRequest]; 
    return [NSArray arrayWithObject:fetchRequest]; 
} 

-(BOOL)shouldDeleteOrphanedObject:(NSManagedObject *)managedObject 
{ 
    return true; 
} 
@end 

我然後對服務器的呼叫ID爲123來獲得用戶，在路徑 「/ API /用戶/ 123」：

User* user = [User object]; 
user.identifier = [NSNumber numberWithInt:123]; 
RKObjectManager* manager = [RKObjectManager sharedManager]; 
[manager getObject:user delegate:self]; 

這工作得很好。但是，當我斷開我的Mac上的WiFi時，上面的代碼不會從sqlite數據庫中檢索用戶。

我收到以下錯誤，而不是在代理的objectLoader:didFailWithError：

憑藉指定緩存應該當有超時，搭配使用的

2012-03-01 11:44:09.402 RestKitCoreDataTest[1989:fb03] error: Error Domain=NSURLErrorDomain Code=-1001 "The request timed out." UserInfo=0x6b89aa0 {NSErrorFailingURLStringKey=http://10.211.55.5:3000/api/users/123, NSErrorFailingURLKey=http://10.211.55.5:3000/api/users/123, NSLocalizedDescription=The request timed out., NSUnderlyingError=0x6b81ac0 "The request timed out."} 

心想：「RKRequestCachePolicyTimeout」，我本來期望用戶將從本地緩存中檢索。

緩存確實包含ID 123的用戶記錄 - 在ZUSER表中，在ZIDENTIFIER列中包含123。

有沒有一個步驟，我錯過了這個工作？也許 需要處理或調用另一個委託方法，當超時時間後 超時後命中緩存？或者我正在嘗試做什麼，這不一定是你用RestKit「開箱即用」的東西？

乾杯。

Answer 1

您可能使用可達性類來確定您的客戶端是否處於脫機狀態。我經常在每個需要互聯網連接的項目中使用這個優秀的課程。

您只需將通知程序啓動到特定主機即可。在所有viewController中，您現在只需向NSNotificationCenter註冊方法即可設置BOOL isOnline。

做這個練習，你可以在你的應用程序中做出漂亮的東西，就像用平滑的「離線」消息覆蓋應用程序一樣。

https://gist.github.com/1182373

編輯

繼承人從我的項目之一登錄畫面一個例子（對不起，這個代碼量，但是這是我的完整的實現）：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 
{ 
    //// Some stuff //// 
    [[Reachability reachabilityWithHostname:@"apple.com"] startNotifier]; 
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(reachabilityChanged:) name:kReachabilityChangedNotification object:nil]; 
} 
- (void)reachabilityChanged:(NSNotification *)note 
{ 
    if ([[note object] isReachable]) { 
     CAKeyframeAnimation *scale = [CAKeyframeAnimation animationWithKeyPath:@"transform.scale"]; 
     [scale setValues:[NSArray arrayWithObjects:[NSNumber numberWithFloat:1.0], [NSNumber numberWithFloat:0.0], nil]]; 
     [scale setDuration:0.3]; 
     [scale setRemovedOnCompletion:NO]; 

     [[offlineView layer] setTransform:CATransform3DMakeScale(0, 0, 1.0)]; 
     [[offlineView layer] addAnimation:scale forKey:@"scale"]; 
     [[offlineView layer] setTransform:CATransform3DIdentity]; 

     [UIView animateWithDuration:0.3 animations:^{ 
      [offlineView setAlpha:0]; 
     } completion:^(BOOL finished){ 
      if (finished) { 
       [offlineView removeFromSuperview]; 
      } 
     }]; 

     [[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleDefault animated:YES]; 
    } 
    else { 
     CGRect screenFrame = CGRectMake(0, 0, 320, 480); 

     offlineView = [[UIView alloc] initWithFrame:screenFrame]; 
     [offlineView setBackgroundColor:[UIColor colorWithWhite:0 alpha:0.7]]; 
     [offlineView setAlpha:0]; 

     offlineLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 200, 30)]; 
     [offlineLabel setFont:[UIFont fontWithName:@"Verdana" size:30.0]]; 
     [offlineLabel setBackgroundColor:[UIColor clearColor]]; 
     [offlineLabel setTextAlignment:UITextAlignmentCenter]; 
     [offlineLabel setTextColor:[UIColor whiteColor]]; 
     [offlineLabel setCenter:[offlineView center]]; 
     [offlineLabel setText:@"OFFLINE"]; 

     [offlineView addSubview:offlineLabel]; 
     [[self window] addSubview:offlineView]; 

     [UIView animateWithDuration:0.3 animations:^{ 
      [offlineView setAlpha:1.0]; 
     }]; 

     [[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleBlackTranslucent animated:YES]; 
    } 
} 

Answer 2

請檢查RestKit的版本;在較新版本的RestKit中，從託管對象存儲中獲取緩存數據的方法略有改變。 我沒有這臺機器的例子;但如果您再需要幫助（因爲這是一個相當古老的問題），請回復。