如果Predicate中的语句不起作用

Question

我IF中的nsfetchresultscontroller声明无效，我无法弄明白为什么。这是一个简单的IF语句，基于使用if ([self.title isEqual: @"Abdominals"])的viewcontroller的静态标题。我的故事板可以在下面看到：

的ViewController

  - (NSFetchedResultsController *)fetchedResultsController {

    if (_fetchedResultsController != nil) {
        return _fetchedResultsController;
    }

    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription
                                   entityForName:@"ExcerciseInfo" inManagedObjectContext:managedObjectContext];
    [fetchRequest setEntity:entity];


    NSSortDescriptor *sort = [[NSSortDescriptor alloc]
                              initWithKey:@"details.muscle" ascending:NO];
    [fetchRequest setSortDescriptors:[NSArray arrayWithObject:sort]];

    [fetchRequest setFetchBatchSize:20];

// Sort Results    
  if ([self.title isEqual: @"Abdominals"]) {

        NSPredicate *predicate = [NSPredicate predicateWithFormat:@"details.muscle == %@", @"Biceps"];
        [fetchRequest setPredicate:predicate];

    }

    else if ([self.title isEqual: @"Arms"]) {

        NSPredicate *predicate = [NSPredicate predicateWithFormat:@"details.muscle == %@", @"Biceps"];
        [fetchRequest setPredicate:predicate ];

    }

    else {

        NSPredicate *predicate = [NSPredicate predicateWithFormat:@"details.muscle == %@", @"Chest"];
        [fetchRequest setPredicate:predicate ];

 }

有什么建议吗？

Answer 1

我认为你正在寻找isEqualToString:

isEqual:比较对象，看起来您想要比较值。