我在core data
中有一列存储日期(eg:2006-01-26)
。我使用了一个数组来存储所有年份,在这些存储日期上使用NSDateComponents
(例如:如果我使用NSDateComponents
,那么我将2006年作为一年)。这些年份是NSNumbers
,并且在我的谓词中使用它们,我想要获取包含所有Date组件的列NSDate
。提取的记录应该只有特定的一年。我现在对如何将一年的组件与一个数组匹配并创建谓词感到困惑。如何使用NSPredicate获取具有NSDate类型的属性?
- (void)viewDidLoad
{
[super viewDidLoad];
NSFetchRequest *request = [[NSFetchRequest alloc]init];
NSError *error;
//AppDelegate *app = [[UIApplication sharedApplication]delegate];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Movies" inManagedObjectContext:self.managedObjectContxt];
[request setEntity:entity];
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc]
initWithKey:@"releaseDate" ascending:YES];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor,nil];
[request setSortDescriptors:sortDescriptors];
//[request setReturnsDistinctResults:YES ];
// [request setEntity:entity];
[sortDescriptors release];
[sortDescriptor release];
[request setPropertiesToFetch:[NSArray arrayWithObject:@"releaseDate"]];
NSMutableArray *arrOfdMovies = [[self.managedObjectContxt executeFetchRequest:request error:&error]mutableCopy];
[self setArrOfFetchdMovies:arrOfdMovies];
arrOfDistinctYr = [[NSMutableArray alloc]init];
NSMutableArray *temp = [[NSMutableArray alloc]init];
for (int i = 0; i<[arrOfdMovies count]; i++) {
// NSLog(@"%@",[[arrOfdMovies objectAtIndex:i] valueForKey:@"releaseDate"]);
//date to its components
NSDate *now = [[arrOfdMovies objectAtIndex:i]valueForKey:@"releaseDate"];
// Specify which units we would like to use
unsigned units = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit;
NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *component_s = [calendar components:units fromDate:now];
NSInteger year = [component_s year];
NSLog(@"%i", year);
// NSInteger month = [components month];
// NSInteger day = [components day];
NSNumber *num= [NSNumber numberWithInteger:year];
[temp addObject:num];
}
[self setArrOfDistinctYr:temp];
//distinct value logic.
NSSet *uniqueYrs = [NSSet setWithArray:arrOfDistinctYr];
arr = [[NSArray alloc]initWithArray:[uniqueYrs allObjects]];
//sorting
NSArray *ar = [arr sortedArrayUsingSelector:@selector(compare:)];
self.arr = ar;
[self.managedObjectContxt retain];
[request release];
}
数组“ar”以不同的和排序的方式仅包含年。但是这个数组元素的数据类型是“NSNumbr” 现在我怎样才能构成一个谓词,它将利用这个数组来显示特定年份的记录(如何检查核心数据的日期字段[ 2006-01-26])。 我试着在下面的方式 -
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
// return 2;
NSFetchRequest *requst=[[NSFetchRequest alloc]init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Movies" inManagedObjectContext:self.managedObjectContxt];
[requst setEntity:entity];
requst.predicate = [NSPredicate predicateWithFormat:@"releaseDate CONTAINS%@", [arr objectAtIndex:section]];
NSError *error = nil;
NSMutableArray *array = [[self.managedObjectContxt executeFetchRequest:requst error:&error]mutableCopy];
[requst release];
return [array count];
}
一旦我得到这个,我可以显示纪录N个我的viewController。
一些代码请..... – iamsult 2012-04-04 05:15:46
我在这里是新的。你可以告诉我如何附加代码? – PriyankaJ 2012-04-04 05:41:24
您可以将您的代码复制并粘贴到您的问题中。然后突出显示您的代码并点击{}按钮。它位于您输入问题的文本框的正上方。这样做会缩进突出显示的区域并显示代码。 – Linger 2012-04-04 15:55:01