How can I present a ModalViewController from a UIActivity item picked from UIActivity View Controller?

问题

I am working on an app that presents some data in a detailViewController. I have a rightBarButton in the navbar that presents a UIActivityViewController that is filled with my own UIActivity sublclassed items. Most of them work fine as they are just changing a small aspect to the data from the detail view, but I need one of them to open a modalViewController when selected. I keep getting the following warning from the console.....

    Warning: Attempt to present <UINavigationController: 0x1fd00590>  
on <UITabBarController: 0x1fde1070> which is already presenting <MPActivityViewController: 0x1fd2f970>

I suppose it is worth noting that the app doesn't crash but the modal view doesn't appear either. I am assuming that the UIActivityViewController is a modal view itself and you can only display one of those at a time so the task is to figure out how to perform my segue after the ActivityView has disappeared, but thats where I am stumped. I welcome any help, thoughts or feedback. I've tried google but haven't had much luck, I assume because The UIActivityViewController is so new.

Here is my setup so far, my UIActivity objects have a delegate set to the detailViewController for a custom protocol that lets the detailViewController perform the data changes and then update its view.

for the activities in question that should present the modalView controller I have tried a few approaches that all get the same warning.

None of These Works!!!

1) simply tried performing segue from my delegate method

- (void) activityDidRequestTransactionEdit
{
    NSLog(@"activityDidRequestTransactionEdit");
    [self performSegueWithIdentifier:@"editTransaction" sender:self];
}

2)tried setting a completion block on the UIActivityViewController and having my delegate method set a bool flag that the modal view should be shown(self.editor)

[activityViewController setCompletionHandler:^(NSString *activityType, BOOL completed) {
    NSLog(@"completed dialog - activity: %@ - finished flag: %d", activityType, completed);
    if (completed && self.editor) {
        [self performSegueWithIdentifier:@"editTransaction" sender:self];
    }
}];

3) subclassing the UIActivityViewController itself, giving it the detailView as a delegate, and overriding it's dismissViewControllerAnimated: method with my own completion block

- (void) dismissViewControllerAnimated:(BOOL)flag completion:(void (^)(void))completion
{
    [super dismissViewControllerAnimated:flag completion:^{
        [self.MPActivityDelegate activityDidRequestTransactionEdit];

    }];
}

The working Solution

In the UIActivity subclass you need to override this method like so

- (UIViewController *) activityViewController {
    MPEditMyDataViewController *controller = [[MPEditMyDataViewController alloc] init];
    controller.activity = self; // more on this property below
    UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:controller];
    return navController;
}

in your MPEditMyDataViewController.h (the view controller the chosen action should produce) You need a property back to the activity subclass like so

@property (strong, nonatomic) MPEditMyDataActivity *activity;

in your MPEditMyDataViewController.m

- (void)viewDidLoad
{
    [super viewDidLoad];
    UIBarButtonItem *cancelButton = [[UIBarButtonItem alloc]
                                     initWithBarButtonSystemItem:UIBarButtonSystemItemCancel
                                     target:self
                                     action:@selector(cancel)];

    self.navigationItem.leftBarButtonItem = cancelButton;
}
// here's how you dismiss the view controller when you are done with it
// after saving the changes to your data or whatever the view controller is supposed to do.
-(void) cancel
{
    NSLog(@"Cancel Button Pushed");
    [self.activity activityDidFinish:YES];
}
@end

回答1:

Did some more documentation digging and found this method for UIActivity subclassing

- (UIViewController *) activityViewController

it gets my view controller to pop up like I wanted by returning it from here instead of trying to segue it from my detailViewController. Now to figure out how to dismiss it when I'm done with it!!!!

来源：https://stackoverflow.com/questions/15369911/how-can-i-present-a-modalviewcontroller-from-a-uiactivity-item-picked-from-uiact

标签

ios6

presentmodalviewcontroller

uiactivityviewcontroller