演示正在进行时演示?尝试在使用parse登录facebook后显示新视图

Question

我正在尝试展示我已经制作的UITableView，供用户放入数据并保存在解析中。我很确定我没有显示导航视图。

当我登录时，我得到错误：

Checklists[4516:c07] Warning: Attempt to present <ChecklistsViewController: 0x10525e90> 
on <UINavigationController: 0x9648270> while a presentation is in progress!

谢谢你的帮助。

#import "LoginViewController.h"
#import "ChecklistsViewController.h"
#import "SetupViewController.h"
#import <Parse/Parse.h>
@interface LoginViewController ()
@end
@implementation LoginViewController
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}
- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    PFLogInViewController *login = [[PFLogInViewController alloc] init];
    login.fields = PFLogInFieldsFacebook;
    // Need to set the delegate to be this controller.
    login.delegate = self;
    login.signUpController.delegate = self; //signUpController is a property on the login view controller
    [self presentModalViewController:login animated:NO];
}
    - (void)logInViewController:(PFLogInViewController *)logInController didLogInUser:(PFUser *)user
{
    [self dismissModalViewControllerAnimated:YES];
    NSLog(@"Successfully logged in.");
    ChecklistsViewController *controller = [[ChecklistsViewController alloc] initWithStyle:UITableViewStylePlain];
    controller.modalTransitionStyle = UITableViewStylePlain;
    [self presentModalViewController:controller animated:YES];
}

Answer 1

在

     presentModalViewController:animated:

你应该用这个代替

    presentViewController:animated:completion:

这个也是如此

    dismissModalViewControllerAnimated:

现在我们使用这个

    dismissViewControllerAnimated:completion:

当我们不想要一个完成块时，我们只需将其设置为零。

但在你的情况下，完成块可以解决你的问题。。。它确保了事件的正确顺序，即在解雇完成之前不会进行演示。

    - (void)logInViewController:(PFLogInViewController *)logInController 
                   didLogInUser:(PFUser *)user
{
    [self dismissViewControllerAnimated:YES completion:^{
        NSLog(@"Successfully logged in.");
        ChecklistsViewController *controller = 
              [[ChecklistsViewController alloc] initWithStyle:UITableViewStylePlain];
        controller.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
        [self presentViewController:controller animated:YES completion:nil];
    }];
}

[NB-modalTransitionStyle在您的原始代码中是不正确的，我也更改了它。感谢Daniel G指出这一点]