我有一个基于核心数据的项目。其中的属性之一称为“日期”,我想从该属性获取值,并且值以字符串“2013-03”开始,但我只能获取最新值,例如字符串“2013-03-30”,如何将所有以“2013-03”开头的值放入NSArray?
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Database" inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"date beginsWith %@",value];
[fetchRequest setPredicate:predicate];
NSSortDescriptor *sortDescription = [[NSSortDescriptor alloc] initWithKey:@"date" ascending:YES];
[fetchRequest setSortDescriptors:@[sortDescription]];
最佳答案
我自己解决了 NSMutableArray *array = [[NSMutableArray alloc] init];
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Database" inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"date beginsWith %@",value];
[fetchRequest setPredicate:predicate];
NSSortDescriptor *sortDescription = [[NSSortDescriptor alloc] initWithKey:@"date" ascending:YES];
[fetchRequest setSortDescriptors:@[sortDescription]];
NSError *fetchError = nil;
NSArray *fetchArray = [self.managedObjectContext executeFetchRequest:fetchRequest error:&fetchError];
if ([fetchArray count] > 0)
{
for (Database *fetchResult in fetchArray)
{
[array addObject:fetchResult.date];
}
}
return array;
关于iphone - 如何在核心数据中使用 NSPredicate 从属性之一获取值,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/15720141/