Question

我如何制作它所以我只用指标== 1获取结果。（我在另一个视图上连接到UISwitch的指示符）。所以我想要一个标题表，但前提是指标是1。

-(void)reload
{
    NSFetchRequest *request = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Event" inManagedObjectContext:managedObjectContext];
    [request setEntity:entity];

    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"Title" ascending:YES]; 
    NSSortDescriptor *sortDescriptor2 = [[NSSortDescriptor alloc]initWithKey:@"indicator" ascending:YES];
    NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, sortDescriptor2, nil]; 
    [request setSortDescriptors:sortDescriptors];
    [sortDescriptors release]; 
    [sortDescriptor release];

    NSError *error = nil; 
    NSMutableArray *mutableFetchResults = [[managedObjectContext executeFetchRequest:request error:&error] mutableCopy]; 
    if (mutableFetchResults == nil) {
        // Handle the error.
    }

    [self setList:mutableFetchResults]; 
    [mutableFetchResults release]; 
    [request release];
}

Answer 1

为您的获取请求添加谓词：

[request setPredicate:[NSPredicate predicateWithFormat:@"indicator == 1"]];

这将导致只返回设置它的事件。我还会从排序描述符中删除sortDescriptor2。当指标键全部具有相同的值时，对指标键的排序没有任何意义。

如果FetchRequest上的语句

1 个答案: