Bug 30250 - UIActivityItemProvider is missing the subject method
Summary: UIActivityItemProvider is missing the subject method
Alias: None
Product: iOS
Classification: Xamarin
Component: Xamarin.iOS.dll ()
Version: master
Hardware: PC Mac OS
: --- normal
Target Milestone: Untriaged
Assignee: Bugzilla
Depends on:
Reported: 2015-05-19 19:06 UTC by George Cook
Modified: 2015-05-20 09:22 UTC (History)
2 users (show)

Is this bug a regression?: ---
Last known good build:

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Description George Cook 2015-05-19 19:06:25 UTC
I can't provide a subject for UIActivityItemProvider, as per this stack overflow answer. it appears to be missing from the class!! That makes it impossible to provide a subject.

Comment 1 Sebastien Pouliot 2015-05-19 21:14:37 UTC
It's not missing since it's not an API that's part of that type, even in ObjC.

`UIActivityItemProvider` is too general to know details about each provider. However you can pass data along (just like the ObjC answer did on SO) like this:

	UIActivityViewController avc = new UIActivityViewController (...);
	avc.SetValueForKey (new NSString ("Your email Subject"), new NSString ("subject"));

At that point it's up to the provider to retrieve the data (subject) and do something with it.
Comment 2 George Cook 2015-05-19 23:17:31 UTC
Okay, that actually worked. Thanks for clarifying. I was confused because:

NS_CLASS_AVAILABLE_IOS(6_0) @interface UIActivityItemProvider : NSOperation <UIActivityItemSource>

in objective c it conforms to UIActivityItemSource
@protocol UIActivityItemSource <NSObject>


- (id)activityViewControllerPlaceholderItem:(UIActivityViewController *)activityViewController;	// called to determine data type. only the class of the return type is consulted. it should match what -itemForActivityType: returns later
- (id)activityViewController:(UIActivityViewController *)activityViewController itemForActivityType:(NSString *)activityType;	// called to fetch data after an activity is selected. you can return nil.


- (NSString *)activityViewController:(UIActivityViewController *)activityViewController subjectForActivityType:(NSString *)activityType; // if activity supports a Subject field. iOS 7.0
- (NSString *)activityViewController:(UIActivityViewController *)activityViewController dataTypeIdentifierForActivityType:(NSString *)activityType; // UTI for item if it is an NSData. iOS 7.0. will be called with nil activity and then selected activity
- (UIImage *)activityViewController:(UIActivityViewController *)activityViewController thumbnailImageForActivityType:(NSString *)activityType suggestedSize:(CGSize)size; // if activity supports preview image. iOS 7.0


And on iOS we implement the optional method subjectForActivityType:(NSString *)activityType

However, for now it solves my issue, and to be honest, these apis are the worst I've found in 5 years of cococa development (Lord knows what hapless noobies they let create the activity view controller mess).  Someone, somewhere might want to be able to implement that delegate method to get fine grained, per activity type subject text; but I'm not that person, so unless you're worried about them, keep it resolved/fixed. 

Comment 3 Sebastien Pouliot 2015-05-20 09:22:58 UTC
I missed the `UIActivityItemSource` protocol when checking this last night. I'll have a second look

> these apis are the worst

IMO the keychain API is even worse ;-)