ios - Dispatch and Delay between calls -

i'm making clone old game simon (a.k.a. genius, in brazil), 1 coloured buttons player needs press following sequence of colors.

for testing, interface has 4 coloured buttons created array button outlets, easy access:

var buttonarray:[uibutton] = [self.greenbutton, self.yellowbutton, self.redbutton, self.bluebutton] 

also, created array store sequence of colors

var colors:[int] = [] 

when game starts calls function adds random number 0 3 (index on buttonarray), , add number colors array after adding new color color sequence, app needs show sequence user, can repeat it

for that, calls playmoves function, uses loop run through colors array , change alpha button, simulating 'blink'

func playmoves(){      let delay = 0.5 * double(nsec_per_sec)     let time = dispatch_time(dispatch_time_now, int64(delay))          in self.colors{              self.buttonarray[i].alpha = 0.2              dispatch_after(time, dispatch_get_main_queue(), {                 self.buttonarray[i].alpha = 1             })                         }     } 

it changes alpha button 0.2 , then, after half second returns alpha 1. using dispatch_after, passing 0.5 seconds , on code block returns alpha, guys can see on code above.

on first run, appears correctly, when colors array has 2 or more items, when runs loop, although has 0.5 sec delay, blinks buttons on same time.

it's dumb mistake i'm making, i'm clueless on moment.

i appreciate help!

thanks!

all of these dispatch_after calls scheduled @ same time, making them appear blink @ same time. there couple of approaches solve this:

you could, example, adjust when parameter (the dispatch_time_t parameter) each button offset original time (such delay was, i * 0.5 * double(nsec_per_sec)).

you use key-frame animation, i'd suggest first try fixing delay in dispatch_after approach first.