Changing UIImageView dynamically - objective-c

Question

-(void)viewDidLoad {
NSMutableArray *coolImagesArray = [[NSMutableArray alloc] initWithObjects:#"active-1.jpg", #"active-2.jpg", #"active-3.jpg", #"active-4.jpg", #"active-5.jpg", nil];
}
-(void)someMethodWithData {
dispatch_async(dispatch_get_main_queue(), ^{
NSMutableArray *imagesArray = [[NSMutableArray alloc] init];
NSMutableString *inactiveString = [[NSMutableString alloc] init];
for (int i = 0; i < progress; i++) {
imageView.image = [UIImage imageNamed:[coolImagesArray objectAtIndex:i]];
inactiveString = [NSMutableString stringWithFormat:#"inactive-%d.png",i];
[imagesArray addObject:imageView];
}
UIImage *setImage = [UIImage imageNamed:#"inactive-1.png"];
for (int i = 0; i < [imagesArray count]; i++) {
[(UIImageView*)[imagesArray objectAtIndex:i] setImage:setImage];
}
});
}
This will always set the last or i(th) image correctly. It will not loop and change all the images I need. Is there another way to manage this?

Answer 1

imageView is pointing to one UIImageView object and in a loop you are changing the image of imageView not adding new UIImageView object to your array. All the objects inside the array pointing to 1 UIImageView object. So it is so normal that you can only change the last object's image only, because there is no other object in your array.
you should do it like:
dispatch_async(dispatch_get_main_queue(), ^{
NSMutableArray *imagesArray = [[NSMutableArray alloc] init];
NSMutableString *inactiveString = [[NSMutableString alloc] init];
for (int i = 0; i < progress; i++) {
UIImageView *temp = [[UIImageView alloc] initWithFrame:imageView.frame];
temp.image = [UIImage imageNamed:[coolImagesArray objectAtIndex:i]];
inactiveString = [NSMutableString stringWithFormat:#"inactive-%d.png",i];
[imagesArray addObject:temp];
}
UIImage *setImage = [UIImage imageNamed:#"inactive-1.png"];
for (int i = 0; i < [imagesArray count]; i++) {
[(UIImageView*)[imagesArray objectAtIndex:i] setImage:setImage];
}
});

Answer 2

For starters, I would create the image once so as to save memory.
I would also cast the object to a UIImageView (Not sure how that isn't getting flagged in xcode).
Lastly I would wrap it in a dispatch_async() to make sure it's happening on the main UI thread, because it could be getting called on a background thread and somehow the last image makes it to the main run loop, either way this is what it would look like:
dispatch_async(dispatch_get_main_queue(), ^{
UIImage *setimage = [UIImage imageNamed:#"set-image.png"];
for (int i = 0; i < [imagesArray count]; i++) {
[(UIImageView *)[imagesArray objectAtIndex:i] setImage:setimage]];
}
});