* 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/api/atom_api_app.cc
mate::Arguments* args) {
  std::vector<JumpListCategory> categories;
  bool delete_jump_list = val->IsNull();
  if (!delete_jump_list &&
      !mate::ConvertFromV8(args->isolate(), val, &categories)) {
    args->ThrowError("Argument must be null or an array of categories");
    return JumpListResult::ARGUMENT_ERROR;
  }
  JumpList jump_list(Browser::Get()->GetAppUserModelID());
  if (delete_jump_list) {
    return jump_list.Delete() ? JumpListResult::SUCCESS
                              : JumpListResult::GENERIC_ERROR;
  }
  
  if (!jump_list.Begin())
    return JumpListResult::GENERIC_ERROR;
  JumpListResult result = jump_list.AppendCategories(categories);
  
  
  if (!jump_list.Commit()) {
    LOG(ERROR) << "Failed to commit changes to custom Jump List.";
    
    
    
    if (result == JumpListResult::SUCCESS)
      result = JumpListResult::GENERIC_ERROR;
  }
  return result;