Question

我在iOS中使用SWRevealViewController导航抽屉。我有一个主屏幕，默认情况下会在应用启动时显示。我还有其他屏幕，如设置，帮助，关于。因此，当用户在屏幕之间切换时，第一个视图控制器的状态会被重置。如果在屏幕上显示一些数据，我想保持它的状态，那么它就不会被删除。

我使用下面的代码在屏幕之间切换。

-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell=[self.tableView cellForRowAtIndexPath:indexPath];
    if(indexPath.row==0)
    {
        [self performSegueWithIdentifier:@"home" sender:cell];
        [cell setSelected:YES];
    }

    else if(indexPath.row==1)
    {
        [self performSegueWithIdentifier:@"settings" sender:cell];
    }

    else if(indexPath.row==2)
    {
        [self performSegueWithIdentifier:@"help" sender:cell];
    }
    else if(indexPath.row==3)
    {
        [self performSegueWithIdentifier:@“about” sender:cell];
    }

}

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    NSLog(@"Segue");
    NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];
    UINavigationController *destViewController = (UINavigationController*)segue.destinationViewController;
    destViewController.title = [[titles objectAtIndex:indexPath.row] capitalizedString];
   if([segue.identifier isEqualToString:@"settings"])
    {
        self.revealViewController.navigationItem.title = @"Settings";

    }
    else  if([segue.identifier isEqualToString:@"help"])
    {
        self.revealViewController.navigationItem.title = @"help";
    }
    else  if([segue.identifier isEqualToString:@"about"])
    {
        self.revealViewController.navigationItem.title = @"about";
    }

    if([segue isKindOfClass:[SWRevealViewControllerSegue class]])
    {
        SWRevealViewControllerSegue *swSegue = (SWRevealViewControllerSegue*) segue;

        swSegue.performBlock = ^(SWRevealViewControllerSegue* rvc_segue, UIViewController* svc, UIViewController* dvc) {
            UINavigationController* navController = (UINavigationController*)self.revealViewController.frontViewController;
            [navController setViewControllers: @[dvc] animated: NO ];
            [self.revealViewController setFrontViewPosition: FrontViewPositionLeft animated: YES];



        };

    }

  }

我看到一个解决方案是将viewController保留在导航堆栈中以便viewController不被破坏，当用户转到“home”时它将保留在堆栈中，然后从导航堆栈重新启动它，而不是再次初始化视图控制器。

Answer 1

例如，对于HelpVC，您将其属性存储在侧面mennu视图控制器中：

@property (nonatomic, strong) HelpViewContoller* helpVC;

比在行选择而不是调用你的segue，你实例化视图控制器，但在此之前你检查它是否已经实例化你已经使用它：

-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *cell=[self.tableView cellForRowAtIndexPath:indexPath];
if(indexPath.row==0) {
    if (helpVC == nil) {
        helpVC =  [self.storyboard instantiateViewControllerWithIdentifier:@"helpVCidentifier"];
        [self changeFrontVCto:helpVC];
    }
}   
 }


-(void) changeFrontVCto:(UIViewController*)vc {
UINavigationController* navController = (UINavigationController*)self.revealViewController.frontViewController;
[navController setViewControllers: @[vc] animated: NO ];
[self.revealViewController setFrontViewPosition: FrontViewPositionLeft animated: YES];
}

在iOS中的SWRevealViewConttoller中持久查看控制器状态？

1 个答案: