Loading more than 10 images on iPhone? - iphone

Question

I'm trying to add more than 10 pictures on ScrollView.
NSUInteger i;
for (i = 1; i <= numberOfImage; i++)
{
NSString *imageName = [NSString stringWithFormat:#"d%dimage%d.png", imageSection, i];
UIImage *image = [UIImage imageNamed:imageName];
UIImageView *imageView = [[UIImageView alloc] initWithImage:image];
// setup each frame to a default height and width, it will be properly placed when we call "updateScrollList"
CGRect rect = imageView.frame;
rect.size.height = kScrollObjHeight;
rect.size.width = kScrollObjWidth;
imageView.frame = rect;
imageView.tag = i; // tag our images for later use when we place them in serial fashion
[scrollView addSubview:imageView];
[imageView release];
}
This code is from Apple example and it works fine. But if the variable 'i' is bigger than 10, 'UIImage *image' is empty. The imageName seems to correct. But I don't know why it does not load image. Does anybody sees the problem??
And one more thing. If I do like that, does iOS controls memory automatically? I mean it's kind of wasting memory if all (more than 10) images are loaded on memory even they are not displayed. I've heard that iOS loads images only displayed on screen and free images those are not displayed. Is that right?
Thanks for reading.

Answer 1

UIimage imageNamed: does cache file contents. I recommend you to use UIImage +imageWithContentsOfFile: that doesn't cache at all in such situation.

Answer 2

You have to make sure the images have the correct name (like 0dimage11.jpg) and are added to the XCode project.

Answer 3

You probably have to set the contentSize accordingly.
IOS will not do that magic memory management thing unless you are using a CATiledLayer based UIView.
If UIImage is not created, it because the name does not refer to an image in the resource folder and you should have an exception.

Answer 4

You need to have the correct file names. You said you think the file names are correct.
NSLog(#"Loop %d: d%dimage%d.png", i,imageSection, i]);
Log out the file names so you can see what the names actually are. Place that line in your loop.
NSUInteger i;
for (i = 1; i <= numberOfImage; i++)
{
NSString *imageName = [NSString stringWithFormat:#"d%dimage%d.png", imageSection, i];
NSLog(#"Loop %d: d%dimage%d.png", i,imageSection, i]);
UIImage *image = [UIImage imageNamed:imageName];
UIImageView *imageView = [[UIImageView alloc] initWithImage:image];
// setup each frame to a default height and width, it will be properly placed when we call "updateScrollList"
CGRect rect = imageView.frame;
rect.size.height = kScrollObjHeight;
rect.size.width = kScrollObjWidth;
imageView.frame = rect;
imageView.tag = i; // tag our images for later use when we place them in serial fashion
[scrollView addSubview:imageView];
[imageView release];
}
Then monitor the filenames in the debugger and see if those image files exist, and in the same directory where Apple put their image files.

Answer 5

Hey,Its not good way to load 10 images at once.All things you have done correct and still you'r image display empty then please check log may be there is memory warning.You can you apple's sample code photoscroller. It will do all thing that you want and also manages good memory.there are two method one is using CATieldLayer and another one directly load images. I recommended you to use method that uses CATieldLayer.

Answer 6

Sorry guys. This is turned out to be my fault. well, not exactly MY fault. Designers throw me many files with wrong filenames like d1imgae11.png... Anyway tips from all you guys gave me different view to see the problem and I got another hint about not to cache images. Thanks.