Coredata获取一个字段的所有值

Question

我有一个实体（“设置”），我想在一个字段（“状态”）中获得所有的值，我正在使用coredata。任何人都可以帮助我吗？

Answer 1

起初，u能获得值的数组：

NSFetchRequest *requestSettings = [[NSFetchRequest alloc] init]; 
[requestCodesList setEntity:[NSEntityDescription entityForName:@"Setting" inManagedObjectContext:managedObjectContext]]; 
NSArray *setting = [managedObjectContext executeFetchRequest:requestCodesList error:&error]; 
if (error) NSLog(@"Failed to executeFetchRequest to data store: %@", [error localizedDescription]); 

接着，U传输U阵列中的NSString：

ComponentsJoinedByString：构造 并返回一个NSString对象，它是 结果在 阵列的元素之间插入给定的 分隔符。

• （的NSString *）componentsJoinedByString：（的NSString *）分离器 代码：

NSString *settingChanged = [setting componentsJoinedByString:@","]; 

和U可以使用üUI这在任何地方后（结合，setStringValue等）

Answer 2

在.h文件中声明这个： NSMutableArray * eventArray;

和.m文件

- (void)fetchRecords { 
    // Setup the fetch request 
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; 

    // Define our table/entity to use 
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Settings" inManagedObjectContext:managedObjectContext]; 

    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"Status" ascending:YES]; 

    NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil]; 

    [fetchRequest setSortDescriptors:sortDescriptors]; 

    [fetchRequest setEntity:entity]; 

    [fetchRequest setEntity:entity]; 

    NSError *error; 

    // Get array of results. 

    NSMutableArray *theResults = [[managedObjectContext executeFetchRequest:fetchRequest error:&error] mutableCopy]; 

    if (!theResults) { 
     // Handle the error. 
     // This is a serious error and should advise the user to restart the application 
    } 

    // Grab unique neighborhoods through NSSet. 

    NSSet *uniqueElements = [NSSet setWithArray:[theResults valueForKey:@"Status"]]; 
    // Dump NSSet uniques into new array. 

    NSMutableArray *sortedResults = [[NSMutableArray alloc] initWithArray:[uniqueElements allObjects]]; 

    for(int i = 0; i < [sortedResults count];i++) 
    { 
     NSLog(@"%d. %@", i+1, [sortedResults objectAtIndex:i]); 
    } 

    // Save our fetched data to an array 

    [self setEventArray: sortedResults]; 
}