使用NSPredicate如何使用1个实体过滤来自核心数据的值
我有一个实体和三个属性，称为项目，比率，类别。 我想过滤来自category属性的值。
if (managedObjectContext==nil) { AppDelegate *appDelegate = (AppDelegate *)[UIApplication sharedApplication].delegate; managedObjectContext = appDelegate.managedObjectContext; } NSFetchRequest *request = [[NSFetchRequest alloc] init]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"Restaurantmenu" inManagedObjectContext:managedObjectContext]; [request setEntity:entity]; NSPredicate *predicate = [NSPredicate predicateWithFormat:@"('category' contains[c] 'Fast Foood')"]; [request setPredicate:predicate]; NSLog(@"Pre %@",predicate); NSError *error = nil; NSMutableArray *mutableFetchResults = [[managedObjectContext executeFetchRequest:request error:&error] mutableCopy]; if (mutableFetchResults == nil) { // Handle the error. } // Set self's events array to the mutable array, then clean up. [self setDataarr:mutableFetchResults]; 但我不能这样做帮助我。
用下面的代码replace谓词的初始化并尝试
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"category CONTAINS[c] %@", @"Fast Foood"];