received memory warning then crash

Question

I want to display multiple images in scrollview when images are more than 70 application will crash and display received memory error.I have get the images from document Directory

I have tried -

 UIScrollView *MyScroll=[[UIScrollView alloc]initWithFrame:CGRectMake(0, 0, 320, 480)];

    int x=5,y=15;

    for (int i = 0; i < imgarr.count; i++)
    {
        if(x<=211)
        {

        UIImage* imagePath = [UIImage imageWithContentsOfFile:[path_array objectAtIndex:i]];

        imgView=[[UIImageView alloc]initWithFrame:CGRectMake(x, y, 77, 75)];
        imgView.image=imagePath;

            imgeBtn=[UIButton buttonWithType:UIButtonTypeCustom];
            imgeBtn.frame=CGRectMake(x, y, 93, 110);
            [imgeBtn addTarget:self action:@selector(btnclick:) forControlEvents:UIControlEventTouchUpInside];
            imgeBtn.tag=i;
            x+=103;

        }
        else
        {
            x=5;
            y+=130;


        UIImage* imagePath = [UIImage imageWithContentsOfFile:[path_array objectAtIndex:i]];

        imgView=[[UIImageView alloc]initWithFrame:CGRectMake(x, y, 77, 75)];
        imgView.image=imagePath;

            imgeBtn=[UIButton buttonWithType:UIButtonTypeCustom];
            imgeBtn.frame=CGRectMake(x, y, 93, 110);
            [imgeBtn addTarget:self action:@selector(btnclick:) forControlEvents:UIControlEventTouchUpInside];
            imgeBtn.tag=i;
            x+=103;

        }
        [MyScroll addSubview:imgeBtn];
        [MyScroll addSubview:imgView];
         MyScroll.contentSize=CGSizeMake(320, y+120);

How can I display multiple images in scrollview?

Answer 1

The advice others have given to switch to a UICollectionView is good, but it has missed the real flaw in your code: the method imageNamed: of UIImage is keeping all 70 of your images in memory forever. Per the docs:

If you have an image file that will only be displayed once and wish to ensure that it does not get added to the system’s cache, you should instead create your image using imageWithContentsOfFile:. This will keep your single-use image out of the system image cache, potentially improving the memory use characteristics of your app.

Switching to this method will prevent the crashes, if you only load into memory the images that you need. UICollectionView makes this trivial, since you can only load image when the collection view asks you to fill out a cell object in its datasource's collectionView:cellForItemAtIndexpath: method.

Answer 2

Create custom class of collection view cell 
and You can pass image name in array. 

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController<UICollectionViewDataSource,UICollectionViewDelegate>

@property (weak, nonatomic) IBOutlet UICollectionView *Collection;

@end

#import "ViewController.h"
#import "CustomCell.h"
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad
{
    [super viewDidLoad];
    [self.Collection registerClass:[CustomCell class] forCellWithReuseIdentifier:@"cell"];
    [self.Collection registerNib:[UINib nibWithNibName:@"CustomCell" bundle:nil] forCellWithReuseIdentifier:@"cell"];
}

-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
    return 5;
}
-(NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
    return 4;
}

-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    CustomCell * cell=[collectionView dequeueReusableCellWithReuseIdentifier:@"cell" forIndexPath:indexPath];
    cell.imgview.image=[UIImage imageNamed:@"XYZ.png"];
    return cell;
}