Make an iPhone InfoButton light/dark based on color behind it

H开发者_如何学JAVAow do I detect what color is under the InfoButton... so I can change the button from DARK to LIGHT?

I set my view's color... but how do I tell if it's "kind of light" or "kind of dark"?

Besides... I can't change the info-button from light to dark anyway. (read only)

Ugh.

Shouldn't Apple have some kind of a simple "cmdButton.doThisExtremelyCommonThingForMe = TRUE" statement?

InfoButtons are useless if you can't even see them.

(Or how would I put an image behind the button to make it stand-out more?)

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but how do I tell if it's "kind of light" or "kind of dark"?

Um, look at it?

Shouldn't Apple have some kind of a simple "cmdButton.doThisExtremelyCommonThingForMe = TRUE" statement?

Yeah, that would be great. But only if they'd also supply a cmdButton.doThisOtherExtremelyCommonThingForMeToo.