* Electron version: 1.6.10
* Operating system: macOS Sierra 10.12.4 (16E195)

# Improve Handoff API support

Hi!

Today the API of Handoff provides the methods: `setUserActivity`, `getCurrentActivityType` and dispatch the event `continue-activity`

I'm using Handoff and noticed that in some circumstances the broadcast takes a long time to update its userInfo which does not happen on the native iOS client

1. To invalidate or resign the current activity we currently need to create a non-existing activity type and set it as the current activity. There's no way to handle the activity life cycle through electron.
2. When we need to update a given user activity userInfo frequently (i.e in response to a search bar's text changes), we have no efficient way. Setting a new userActivity with the updated information takes several seconds to bridge, whereas doing this on iOS native app is instantaneous.

I believe that exposing a bit more of the NSUserActivity API to Electron would help, namely `becomeCurrent`, `resignCurrent` and `invalidate` which would address point 1, and `needsSave` and a new event to allow updating an activity when needed to address point 2.
These are described in more detail in https://developer.apple.com/reference/foundation/nsuseractivity.

I'm are open to help in any way i can such as explaining how the native API work, providing sample code or testing possible implementations

Thank you!
atom/browser/mac/atom_application.h
NSColor* systemGreenColor API_AVAILABLE(macosx(10.10));
@property(class, strong, readonly)
    NSColor* systemOrangeColor API_AVAILABLE(macosx(10.10));
@property(class, strong, readonly)
    NSColor* systemPinkColor API_AVAILABLE(macosx(10.10));
@property(class, strong, readonly)
    NSColor* systemPurpleColor API_AVAILABLE(macosx(10.10));
@property(class, strong, readonly)
    NSColor* systemRedColor API_AVAILABLE(macosx(10.10));
@property(class, strong, readonly)
    NSColor* systemYellowColor API_AVAILABLE(macosx(10.10));
@property(class, strong, readonly)
    NSColor* linkColor API_AVAILABLE(macosx(10.10));
@property(class, strong, readonly)
    NSColor* placeholderTextColor API_AVAILABLE(macosx(10.10));
@property(class, strong, readonly)
    NSColor* findHighlightColor API_AVAILABLE(macosx(10.13));
@property(class, strong, readonly)
    NSColor* separatorColor API_AVAILABLE(macosx(10.14));
@property(class, strong, readonly)
    NSColor* selectedContentBackgroundColor API_AVAILABLE(macosx(10.14));
@property(class, strong, readonly)
    NSColor* unemphasizedSelectedContentBackgroundColor API_AVAILABLE(
        macosx(10.14));
@property(class, strong, readonly)
    NSColor* unemphasizedSelectedTextBackgroundColor API_AVAILABLE(macosx(10.14)
    );
@property(class, strong, readonly)
    NSColor* unemphasizedSelectedTextColor API_AVAILABLE(macosx(10.14));
@end