ios - Swift NSArray out-of-index with no apparent reason -

i'm working popups impressions , did far declaring nsarray

var queue = [popupclass]() 

then i'm populating aforementioned array 5 static instances of class right in viewdidload method:

var queue = [pop1, pop2, pop3, pop4, pop5] 

i'm putting first element @ bottom of array given amount of times:

for (var = 0; < 12; i++) {     queue[0].impression++     queue.append(queue[0])     queue.removeatindex(0) } 

this works fine if put instruction line line in viewdidload function. if put same code in method (named refreshimpressions) , recall method still in viewdidload, app crashes because array goes out-of-range @ first element.

override func viewdidload() {     super.viewdidload()      refreshimpressions() } 

any appreciated. sorry if english might sound bad it's not mother language.