What control events start and end highlight state of UIButton

Question

I am creating piano-like view with UIButton as piano keys. What UIControlEvents should I listen for to get callbacks when button gets and loses highlighted state?

I tried to make subclass of UIButton and add property observer for highlighted and it was working fine. However sometimes I need to set highlighted state manually from code and that really messes it up as there is no way to tell whether event was user or app initiated.

Publicspirited

Do you think you will get any callback to even listen to AllEvents when modified highlighted state from code? – Wimberly

If I understand your problem right I think you should use UIControlEventTouchUpInside and UIControlEventTouchUpOutside event – Kenspeckle

Maybe use a boolean as an on/off toggle to keep track of the state... – Bulbiferous

Answer 1

To mimic piano key behavior I used the following UIControlEvents:

self.addTarget(self, action: "pressed", forControlEvents: [.touchDown])
self.addTarget(self, action: "released", forControlEvents: [.touchDragExit, .touchUpInside, .touchUpOutside, .touchCancel])

Publicspirited

You may also want touchDragEnter to trigger pressed – Electrograph

You also probably don't need touchUpOutside since it necessarily happens after touchDragExit – Electrograph

Answer 2

gets highlighted state:UIControlEventTouchDown

lose highlighted state:UIControlEventTouchDragOutside

Stannfield