iPhone (UIKit)

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Approximate Implementation Notes

class EngagementManager : UIView

struct SInterUnit 

(base functions and data needed by all InterUnits

to interface with the EngagementManager)

protocol PInterUnit

(additional functions required for all concrete InterUnits.

All concrete InterUnits are SInterUnits that implement PInterUnit)

1. Frame-buffer access

override UIView::draw(_:)

{

UIGraphicsGetCurrentContext()

UIGraphicsPushContext(_:)

(draw the InterUnit stack in back to front order)

UIGraphicsPopContext()

}

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2. User-input response 

UIPress

(UIKit sends this general purpose descriptive object to the UIView

for keyboard, mouse and touch events)

UIView::setNeedsDisplay(_:) 

(request for a draw, full or partial)