获取特定项的coredata-ios
我是c目标的新手。我已将记录保存在核心数据中 我想获取一个备用_id=523的记录获取特定项的coredata-ios,ios,objective-c,Ios,Objective C,我是c目标的新手。我已将记录保存在核心数据中 我想获取一个备用_id=523的记录 如何在核心数据中实现这一点 AppDelegate* app = (AppDelegate*)[UIApplication sharedApplication].delegate; MyEntity* entity = nil; NSInteger myID = 523; NSFetchRequest *request = [[NSFetchRequest alloc] init]; [request setE
如何在核心数据中实现这一点
AppDelegate* app = (AppDelegate*)[UIApplication sharedApplication].delegate;
MyEntity* entity = nil;
NSInteger myID = 523;
NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity: [NSEntityDescription entityForName:@"MyEntity" inManagedObjectContext:app.managedObjectContext]];
NSPredicate* predicate = [NSPredicate predicateWithFormat:@"alternate_id = %@",@(myID)];
[request setPredicate:predicate];
NSArray* array = [app.managedObjectContext executeFetchRequest:request error:nil];
if([array count] > 0)
{
entity = [array objectAtIndex:0];
}
请显示您尝试过的代码
NSError *error = nil;
NSManagedObjectContext *managedObjectContext = [Your managedContext];
NSEntityDescription *entityDescription = [NSEntityDescription entityForName:@"YourEntityName" inManagedObjectContext:managedObjectContext];
NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity:entityDescription];
NSPredicate *predicateObj = [NSPredicate predicateWithFormat:@"(alternate_id ==%@)", @"523"];
[request setPredicate:predicateObj];
NSArray *resultArray = [managedObjectContext executeFetchRequest:request error:&error];
YourEntity *yourEntityObj = nil;
if (resultArray && [resultArray count]>0) {
yourEntityObj = [resultArray objectAtIndex:0];
}