将NSString发送到另一个UIViewController给出null

在您的代码中,您做错了,您应该初始化正在推送到navigationController的viewController,您正在初始化 viewTo 但你在努力 self.subViewController .

应该这样初始化;

self.subViewController= [[SubViewViewController alloc] initWithNibName:@"SubViewViewController" bundle:[NSBundle mainBundle]];

在这里找零

[self.navigationController pushViewController:viewTwo animated:YES];

在SecondViewcontroller.h文件中进行更改

{
NSString             *queryValue;
}
@property (nonatomic, strong) NSString *queryValue;

你在推 self.subViewController 但你正在将字符串传递给 viewTwo 。这是两个不同的对象。请改用此行:

[self.navigationController pushViewController:viewTwo animated:YES];

添加:
self.subViewController = viewTwo;

请使用以下代码

-FirstView控制器:

  - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
    {

        [_tableView deselectRowAtIndexPath:indexPath animated:YES];

self.subViewController = [[SubViewViewController alloc] initWithNibName:@"SubViewViewController" bundle:[NSBundle mainBundle]];


        viewTwo.queryValue = [NSString stringWithFormat:@"%d",indexPath.row];

        [self.navigationController pushViewController:self.subViewController animated:YES];
    }

-SecondView控制器.h:

@property (nonatomic, retain) NSString *queryValue;

-SecondView控制器.m:

- (void)viewDidLoad
{
    [super viewDidLoad];

    NSLog(@"%@", self.queryValue);
}