批量更新iOS 7中的數據CoreData

Question

是否有方法通過一個SQL查詢運行某個實體的所有對象的更新？ 不能獲取和運行循環。

例如喜歡跑

UPDATE someEntity SET filed1 = value1 WHERE field2 = value2 

Answer 1

Mercelo的回答不會爲iOS7工作，爲此，您可以

NSFetchRequest *fetchAllRSSItems = [NSFetchRequest fetchRequestWithEntityName:[RSSItem entityName]]; 
NSError *fetchError; 
NSArray *results = [self.managedObjectContext executeFetchRequest:fetchAllRSSItems error:&fetchError]; 

if (results == nil) { 

    NSLog(@"Error: %@", [fetchError localizedDescription]); 
} else { 

    for (RSSItem *rssItem in results) { 
     rssItem.read = [NSNumber numberWithBool:YES]; 
    } 

    [self saveManagedObjectContext]; 
} 

Answer 2

核心數據批量更新引入了在iOS 8：

NSBatchUpdateRequest *batchRequest = [NSBatchUpdateRequest batchUpdateRequestWithEntityName: [RSSItem entityName]]; 
batchRequest.propertiesToUpdate = @{NSStringFromSelector(@selector(read)): @YES}; 
batchRequest.resultType = NSStatusOnlyResultType; // NSStatusOnlyResultType is the default 
batchRequest.affectedStores = @[...]; // Optional, stores this request should be sent to 
batchRequest.predicate = [NSPredicate predicateWithFormat:@"..."]; // Optional, same type of predicate you use on NSFetchRequest 

NSError *requestError; 
NSBatchUpdateResult *result = (NSBatchUpdateResult *)[self.managedObjectContext executeRequest:batchRequest error:&requestError]; 

if (result) { 
    // Batch update succeeded 
} else { 
    NSLog(@"Error: %@", [requestError localizedDescription]); 
} 

但是，它並沒有改變背景：它直接改變了持久性存儲。這意味着沒有進行驗證，您需要更新您的用戶界面後。

這個答案是根據this post by Matthew Morey。