UICollectionView with images : Memory increases up to 1.75 GB - ios

Question

My iPhone App displays a CollectionView with about 100 Images separated by Headers. The Images have a size from about 200Kb. In the debug navigator the memory increases up to 1.75 GB while scrolling the CollectionView. It still runs smooth, but there must be a reason for that.
#property (strong, nonatomic) NSArray *picturesMoon;
#property (strong, nonatomic) NSArray *picturesEarth;
#property (strong, nonatomic) NSArray *picturesVenus;
#property (strong, nonatomic) NSArray *picturesMars;
#property (strong, nonatomic) NSDictionary *plistDict;
#property (strong, nonatomic) NSString *picName;
#property (strong, nonatomic) MyCustomCell *myCell;
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
self.view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:#"Milkyway.png"]];
self.plistDict=[[NSDictionary dictionaryWithContentsOfFile:[[NSBundle mainBundle] pathForResource:#"Praxis" ofType:#"plist"]] objectForKey:#"Universe"];
// Pictures Moon
picturesMoon = [self.plistDict objectForKey:#"Moon"];
// Pictures Earth
picturesEarth = [self.plistDict objectForKey:#"Earth"];
// Pictures Mars
picturesMars = [self.plistDict objectForKey:#"Mars"];
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
self.myCell = [collectionView dequeueReusableCellWithReuseIdentifier:#"collectionCell" forIndexPath:indexPath];
// Sections
switch (indexPath.section) {
case 0:
self.myCell.imageInCell.image = [UIImage imageNamed:[picturesMoon objectAtIndex:indexPath.item]];
break;
case 1:
self.myCell.imageInCell.image = [UIImage imageNamed:[picturesEarth objectAtIndex:indexPath.item]];
break;
case 2:
self.myCell.imageInCell.image = [UIImage imageNamed:[picturesMars objectAtIndex:indexPath.item]];
break;
case 3:
self.myCell.imageInCell.image = [UIImage imageNamed:[picturesVenus objectAtIndex:indexPath.item]];
break;
default:
break;
}
return self.myCell
}
- (UICollectionReusableView *) collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
{
// Header for Sections
HeaderCollectionView *myHeaderView = [collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:#"Header" forIndexPath:indexPath];
switch (indexPath.section) {
case 0:
myHeaderView.labelOutlet.text = #"Moon";
break;
case 1:
myHeaderView.labelOutlet.text = #"Earth";
break;
...
...
default:
break
}
return myHeaderView;
}
MyCustomCell is just a few line of Code
#import "MyCustomCell.h"
#implementation MyCustomCell
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
}
return self;
}
and the Header for MyCustomCell just
#import <UIKit/UIKit.h>
#interface MyCustomCell : UICollectionViewCell
#property (strong, nonatomic) IBOutlet UIImageView *imageInCell;
#end

Answer 1

[UIImage imageNamed:] caches the images. The large memory footprint isn't necessarily a problem, as the cache will be automatically purged if memory is too low. That said, if you want to avoid caching, you can use another method to load the images, for example:
NSString *imageName = [picturesMars objectAtIndex:indexPath.item];
NSString *imagePath = [[NSBundle mainBundle] pathForResource:imageName ofType:#"PNG"]; // PNG, or whatever file tile you are actually using
UIImage *image = [UIImage imageWithContentsOfFile:imagePath];
self.myCell.imageInCell.image = image;