Core data 用于获取字段所有值的Coredata

我有一个实体（“设置”），我想在一个字段（“状态”）中获取所有值。我使用的是coredata。有人能帮我吗

首先，u可以得到一组值：

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]); 

接下来，u传输NSString中的u阵列：

ComponentsJoinedByString:构造 并返回一个NSString对象，该对象为 插入给定值的结果 元素之间的分隔符 数组

• （NSString*）组件通过字符串连接：（NSString*）分隔符 代码是：

在您可以在UI中的任何位置使用此选项后（binding，setStringValue e.t.c）

在.h文件中声明此选项： NSMutableArray*eventArray

在.m文件中

- (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];
}

-（void）fetchRecords{
//设置获取请求
NSFetchRequest*fetchRequest=[[NSFetchRequest alloc]init]；
//定义要使用的表/实体
NSEntityDescription*实体=[NSEntityDescription entityForName:@“设置”在managedObjectContext:managedObjectContext中]；
NSSortDescriptor*sortDescriptor=[[NSSortDescriptor alloc]initWithKey:@“状态”升序：是]；
NSArray*sortDescriptors=[[NSArray alloc]initWithObjects:sortDescriptor，nil]；
[FetchRequestSetSortDescriptors:sortDescriptors]；
[FetchRequestSetEntity:entity]；
[FetchRequestSetEntity:entity]；
n错误*错误；
//获取结果数组。
NSMutableArray*theResults=[[managedObjectContext executeFetchRequest:fetchRequest错误：&错误]mutableCopy]；
如果（！theResults）{
//处理错误。
//这是一个严重错误，应建议用户重新启动应用程序
} 
//通过NSSet获取独特的社区。
NSSet*uniqueElements=[NSSet setWithArray:[theResults valueForKey:@“Status”]；
//将NSSet UNIQUE转储到新阵列中。
NSMutableArray*sortedResults=[[NSMutableArray alloc]initWithArray:[uniqueElements allObjects]]；
对于（int i=0；i<[sortedResults count]；i++）
{
NSLog（@“%d.%@”，i+1，[sortedResults objectAtIndex:i]）；
}
//将提取的数据保存到数组中
[self-setEventArray:sortedResults]；
}

您是否试图获取所有设置对象中“状态”的所有值的列表？你在乎复制品吗？

- (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];
}