UIButton cannot be displayed - ios

Question

in my app i'm using a scroll View (paging). each view in the scroll view (UIImageView) contains an image and each image has tags (buttons) scattered all over the pic. so here is my code:
for (int i = 0; i < self.pictures.count; i++)
{
//The first loop is to loop to every picture
int nbOfTags = classObject.tagsImages.count;
for (int j = 0; j < nbOfTags; j++)
{
//Second loop is to loop to each tag corresponding to the picture
ListTags *listTags = [[ListTags alloc]init];
NSMutableArray *tagInfo = [[NSMutableArray alloc]init];
listTags = [tagInfo objectAtIndex:j];
float tagX = [listTags.tag_x floatValue];
float tagY = [listTags.tag_y floatValue];
float x = 1024*i+ tagX;
float y = tagY;
CGRect rect = CGRectMake(x, tagY, 20, 20);
UIButton *button = [[UIButton alloc] initWithFrame:rect];
UIImage * buttonImage = [UIImage imageNamed:#"blueCircle.png"];
[button setBackgroundImage:buttonImage forState:UIControlStateNormal];
[self.scrollView addSubview:button];
}
}
problem: when i run the code i can't see the buttons (tags) on the picture. if i replace "i" with "j" in
float x = 1024*i+ tagX;
the buttons can be seen, however it's not the desired coordinates. so why "i" can't work? am i doing anything wrong or missing anything?

Answer 1

In interface builder (or storyboard - IB) uncheck autolayout (if it's checked) then your button will be displayed where you want.

Answer 2

See my comments in the code below:
for (int i = 0; i < self.pictures.count; i++)
{
//The first loop is to loop to every picture
/*
* This will give you the same number of tags for every image.
* Is that what you want?
*/
int nbOfTags = classObject.tagsImages.count;
for (int j = 0; j < nbOfTags; j++)
{
//Second loop is to loop to each tag corresponding to the picture
/* This allocates a brand new ListTags object EVERY time through the loop. */
ListTags *listTags = [[ListTags alloc]init];
/* This allocates a brand new EMPTY array EVERY time through the loop. */
NSMutableArray *tagInfo = [[NSMutableArray alloc]init];
/*
* This discards the new ListTags object that you just created two lines ago
* and replaces it with an object from tagInfo. Which doesn't exist because
* you just created a new array in the previous line. This really should
* crash, which leads me to believe that this isn't the actual code that you
* are using. Post the actual code that you are using so that we can help you
* better.
*/
listTags = [tagInfo objectAtIndex:j];
/* None of this is valid since listTags is nil/we never should have gotten here. */
float tagX = [listTags.tag_x floatValue];
float tagY = [listTags.tag_y floatValue];
float x = 1024*i+ tagX;
float y = tagY;
CGRect rect = CGRectMake(x, tagY, 20, 20);
UIButton *button = [[UIButton alloc] initWithFrame:rect];
UIImage * buttonImage = [UIImage imageNamed:#"blueCircle.png"];
[button setBackgroundImage:buttonImage forState:UIControlStateNormal];
[self.scrollView addSubview:button];
}
}