Switch Indeterminate State

[agam16]

I am working on an app in which i have one parent switch and its children switches. so when i change the parent switch, it changes all child switches. If all child switches are in on state, then the parent switch also shows in on state, but if one of the child switch is turned off, the parent switch should also change to indeterminate state as if there is no indeterminate state, then the parent switch is turned to off state and its ng-change is called automatically which inturns switches off the child.

Please let me know what can i do to proceed?