UIActivityViewController/UIPopoverPresentationController Crash on iPads running iOS 8

[jaredsinclair]

In iOS 8, Apple has "soft-deprecated" UIPopoverController, replacing it with UIPopoverPresentationController. Behind the scenes this means that sometimes a UIPopoverPresentationController is being used without the developer's explicit intent to do so.

Case in point the 1Password app extension. The following line of code leads to a crash on iPads running iOS 8:

- (void)findLoginForURLString:(NSString *)URLString forViewController:(UIViewController *)viewController sender:(id)sender completion:(void (^)(NSDictionary *loginDictionary, NSError *error))completion {
    // ...
    [viewController presentViewController:activityViewController animated:YES completion:nil];
}

With the following crash log:

*** Terminating app due to uncaught exception 'NSGenericException', reason: 'UIPopoverPresentationController (<_UIAlertControllerActionSheetRegularPresentationController: 0x13ed0d8f0>) should have a non-nil sourceView or barButtonItem set before the presentation occurs.'

What's happening is that UIKit is forcing the activity view controller to be presented in a popover, but it isn't setting a sourceView/sourceRect pair nor a barButtonItem, leading to the above crash. This is undocumented behavior but I've seen it in other apps and contexts.

Suggested workarounds (both assume getting a reference to the activity view controller's popover presentation controller and setting the required properties):

1. Hacky Bullshit – Just use viewController's view as the sourceView/sourceRect on iPad.
2. Better – Provide an alternate public API for implementers to explicitly provide a sourceRect/sourceView pair or barButtonItem when calling the extension.

[jaredsinclair]

Here's a link to a sample project: https://www.dropbox.com/s/yu62ul8i8vwfkto/Crasher.zip?dl=0

[radazzouz]

Hi @jaredsinclair,

Thanks so much for taking the time to write a demo app. This really helps us tremendously 👍

I'm pretty sure that - (void)findLoginForURLString:(NSString *)URLString forViewController:(UIViewController *)viewController sender:(id)sender completion:(void (^)(NSDictionary *loginDictionary, NSError *error))completion is already designed to take a bar button item as a sender. So the better scenario that you suggested already works.

Below you'll see the changes that I made to your code and it works fine here. No crash whatsoever.

- (void)onePasswordButtonTapped:(id)sender {
    [[OnePasswordExtension sharedExtension] findLoginForURLString:@"twitter.com" forViewController:self sender:self.navigationItem.rightBarButtonItem completion:^(NSDictionary *loginDict, NSError *error) {
        // do stuff
    }];
}

Please let me know whether this helps.

Cheers!

[jaredsinclair]

Okay. sender wasn't typed or documented, so that wasn't clear. In any case I still recommend Option 2 since not all iPad apps are going to be able to use a bar button item, but will need an explicit sourceView/sourceRect pair. Thanks for following up.

[radazzouz]

Hi @jaredsinclair,

Thanks for getting back to me so quickly 👍

We already do an explicit sourceView/sourceRect pair in - (UIActivityViewController *)activityViewControllerForItem:(NSDictionary *)item viewController:(UIViewController*)viewController sender:(id)sender typeIdentifier:(NSString *)typeIdentifier, which is called in - (void)findLoginForURLString:(NSString *)URLString forViewController:(UIViewController *)viewController sender:(id)sender completion:(void (^)(NSDictionary *loginDictionary, NSError *error))completion

- (UIActivityViewController *)activityViewControllerForItem:(NSDictionary *)item viewController:(UIViewController*)viewController sender:(id)sender typeIdentifier:(NSString *)typeIdentifier {
#ifdef __IPHONE_8_0

    NSItemProvider *itemProvider = [[NSItemProvider alloc] initWithItem:item typeIdentifier:typeIdentifier];

    NSExtensionItem *extensionItem = [[NSExtensionItem alloc] init];
    extensionItem.attachments = @[ itemProvider ];

    UIActivityViewController *controller = [[UIActivityViewController alloc] initWithActivityItems:@[ extensionItem ]  applicationActivities:nil];

    if ([sender isKindOfClass:[UIBarButtonItem class]]) {
        controller.popoverPresentationController.barButtonItem = sender;
    }
    else if ([sender isKindOfClass:[UIView class]]) {
        controller.popoverPresentationController.sourceView = [sender superview];
        controller.popoverPresentationController.sourceRect = [sender frame];
    }
    else {
        NSLog(@"sender can be nil on iPhone");
    }

    return controller;
#else
    return nil;
#endif
}

I just filed issue #148 to improve the in-code documentation.

Please let me know if there's anything else that I can do to help 😉

Cheers!

[radazzouz]

Closing this issue. The documentation will be addressed in issue #148