objective-c - NSMutableSet不添加对象

我的代码没有在集合中添加元素。

我的头文件如下:

#import <UIKit/UIKit.h>

@interface NHPSearchViewController : UITableViewController
//For using the local DB
@property (strong, nonatomic) NSManagedObjectContext *managedObjectContext;
//texst field where user enters a substance name or a drug name
@property (weak, nonatomic) IBOutlet UITextField *substanceTextField;

//An array for Drug Names, and another array for NHPs
@property (strong, nonatomic) NSMutableSet *drugList;
@property (strong, nonatomic) NSMutableSet *NHPList;
//Contains both drugList and NHP list as one array for the data to be shown for the user.
@property (strong, nonatomic) NSMutableSet *usersList;

@end

我的.m文件:

@interface NHPSearchViewController ()
- (BOOL) checkAndAddToList: (NSString *) substance;
@end

@implementation NHPSearchViewController

@synthesize managedObjectContext;
@synthesize substanceTextField;
@synthesize drugList, NHPList, usersList;

//"Private" helper methods

-(BOOL) checkAndAddToList:(NSString *)substance{
    //  Set up a predicate for testing if the data exists in the table
    NSPredicate *pred = [NSPredicate predicateWithFormat:@"name == %@", substance];

    //Run the query to see if the substance is in the Substances Table.
    NSMutableArray  *results =[NSMutableArray array];
    results = [CoreDataHelper searchObjectsForEntity:@"Substances" withPredicate:pred andSortKey:nil andSortAscending:NO andContext:self.managedObjectContext];

        if ([results count] > 0){
        //Found the substance return YES
            Substances *sub = [results objectAtIndex:0];
            NSLog(@"Did find a result with name:%@  and class_name as:%@ ",[sub name], [sub class_name]);

            //add the name to the appropriate lists.
            if([[sub class_name] isEqualToString:@"NHP"]){
                NSLog(@"NHP was found adding it to the nhp list");
                [NHPList addObject:[sub name]];  //THIS is not working
                NSLog(@"NHP count after adding %i", [NHPList count]);
            }else if ([[sub class_name] isEqualToString:@"Drugs"]){
                NSLog(@"Drug was found adding it to the drug list");
                [drugList addObject:[sub name]];  //THIS is also not working
            }

            //add the name to our list in the view
            [usersList addObject:[sub name]]; //This is also not working

            return YES;
    }else{
      //
       return YES;

    }
 return NO;
}

日志输出:

[4187:fb03]测试实质文本字段值:Ω3-6-9 [4187:fb03]
确实找到了名称为:Omega 3-6-9和class_name为:NHP的结果
[4187:fb03]已发现NHP将其添加到nhp列表中[4187:fb03] NHP
加0后计数[4187:fb03] NHP列表:0药品列表:0用户列表:0

最佳答案

在使用集合之前的某个时候，您需要创建一个新的NSMutableSet。

为了简化操作，您可以在第一次要求使用新的可变集时使用如下所示的方法自动分配新的可变集。

- (NSMutableSet *)NHPList {
    if (NHPList == nil) {
        NHPList = [[NSMutableSet alloc] init];
    }
    return NHPList;
}

您还必须通常通过将viewDidUnload设置为NHPList来在nil方法中释放内存。

如果这是设置数据的唯一位置，则还可以更改以下行:

[NHPList addObject:[sub name]];

至:

if (self.NHPList == nil) {
    self.NHPList = [[NSMutableSet alloc] init];
}
[self.NHPList addObject:[sub name]];