You should create an array of dictionary objects, with each dictionary object containing one image, one sound and one text object (the same name ones). So the array will contain 36 dictionary objects and each dictionary object will contain 3 objects each.
NSMutableArray *combinedArray = [[NSMutableArray alloc] init];
for(i=0;i<36;i++) {
NSDictionary *dict = [[NSDictionary dictionaryWithObjectsAndKeys:[imageArray objectAtIndex:i], @"image", [textArray objectAtIndex:i], @"text", [soundArray objectAtIndex:i], @"sound", nil]];
[combinedArray addObject:dict];
}
Now you can use arc4Random on the combinedArray, and you'll have all the 3 corresponding objects at the selected random index. Hope this helps