For Android L:
If you set [Show all notification content], and if we are using custom view, then we can make actions without unlock the screen regardless the security level (Pin, Pattern, Password).
But if we want to hide notification from some sensitive app when the screen is locked, then we can follow this procedure to make notifications be hidden.
· Open your device's Settings menu
· Under "Device," touch Sound & notification.
· Touch App notifications.
· Select the app you want to change notifications for.
· You can change the following settings, depending on the app:
Sensitive: You need to be in "Show all notifications" mode and have a pin, password, or pattern set up as your screen lock in order to see this setting. Notifications for the app selected will still appear on your lock screen, but their contents will not be visible.
So we can make sure some apps be sensitive like Email, Contact, SMS.
For Android L below:
Only set security level as Swipe or None, which allow users to slide down the notification panel.