Question

我有大约20个实体：Event1 ... Event20 在每个实体中，我有属性值1 ... values20

我需要记录数据，例如Event5 values8

但是出了点问题 - 可能是每个值8中的数据记录（Event1 ... Event20）

怎么做对了？

    NSString *str = [NSString stringWithFormat:@"Event%d", variable];
 NSString *value  = [NSString stringWithFormat:@"values%d", vari];


 TermometrAppDelegate *app;
 app = (TermometrAppDelegate *)[UIApplication sharedApplication].delegate;

 NSFetchRequest *fetchRequests = [[NSFetchRequest alloc] init];
NSEntityDescription *entit = [NSEntityDescription entityForName:str      inManagedObjectContext:app.managedObjectContext];

   [fetchRequests setEntity:entit] ;
   [fetchRequests setPropertiesToFetch :[NSArray arrayWithObject:value]];  
    [fetchRequests setReturnsDistinctResults:YES];
   NSError *error;
      NSArray *fetchedObject = [app.managedObjectContext executeFetchRequest:fetchRequests error:&error];
      NSManagedObject *fetched = nil;
     NSManagedObject *fetch = nil;
      printf("\n%d", [fetchedObject count]);

Answer 1

下面的代码检索Entity5中Value8的值等于someValueForEight.text（UITextField）。这应该可以帮到你。

        TermometrAppDelegate *app;
        app = (TermometrAppDelegate *)[UIApplication sharedApplication].delegate;

        NSManagedObjectContext *context = [app managedObjectContext];
        NSEntityDescription *entityDesc = [NSEntityDescription entityForName:@"Entity5" inManagedObjectContext:context];
        NSFetchRequest *request = [[NSFetchRequest alloc] init];

        [request setEntity:entityDesc];
        NSPredicate *pred = [NSPredicate predicateWithFormat:@"(value8 = %@)", someValueForEight.text];
        [request setPredicate:pred];

        NSManagedObject *matches = nil;
        NSError *error;

        NSArray *objects = [context executeFetchRequest:request error:&error];

将数据记录到核心数据Iphone中的属性

1 个答案: