Android - "Google Now" swipe from Home button is not working in Marshmallow
There are actually 2 issues here:
- No swipe from Home button gesture
- Cannot change the action from Google Now to other apps (e.g Tasker, or Greenify)
The first issue is caused to accomodate a new feature called Now on Tap. Now, instead of swiping the Home button, you just need to hold it to access Google Now screen (or "Now on Tap", if enabled). AFAIK, this behaviour cannot be changed natively (enabling/disabling "Now on Tap" doesn't affect this).
The second issue is caused by the addition of explicit setting for assist app (before Marshmallow, you need to clear defaults the app that you assign to before). The setting can be accessed from Settings - Apps - Advanced (cog wheel icon) - Default Apps - Assist & voice input - Assist app. By default, it is "Google App" (i.e. Google Now), and you can change to any apps that support this feature (i.e. Tasker, for my case).
Simply go to:
Settings > apps > setting icon > default apps > Assist & voice input > assist app
In there you will find a list of apps, you choose google, now it will be selected. I use the home button to lock my phone with screen lock app. You should find greenify in there too,if you have it.
I figured it out. Actually in marshmallow, the swipe up gesture is replaced by the 'holding the home button' gesture. If you turn off the 'now on tap', the google now will launch if you hold the home button. I guess this is one of marshmallow's changelog...