CODEWITHSUNDEEP
objective-ciosuiscrollview
dineshprasanna
dineshprasanna

Reputation: 1284

adding 1000 images in the scrollview of ios app

in my ios app i am trying to load 1000 images in a scroll view, when i run the code it gets crashed. I found it to be the out of memory error. I tried adding 700 images but there is no crash. But i want to add more than 1000 images(around 4000) and to be viewed. how to manage all the images and get them without any crash.

please help me friends

Upvotes: 0

Views: 763

Answers (2)

LJ Wilson
LJ Wilson

Reputation: 14427

I don't know where your images are coming from but I wrote a custom method (in a class called WebImageOperations) to load images using blocks and GCD:

Here is the Class: WebImageOperations.h

#import <Foundation/Foundation.h>

@interface WebImageOperations : NSObject {
}

// This takes in a string and imagedata object and returns imagedata processed on a background thread
+ (void)processImageDataWithURLString:(NSString *)urlString andBlock:(void (^)(NSData *imageData))processImage;
@end

WebImageOperations.m

#import "WebImageOperations.h"
#import <QuartzCore/QuartzCore.h>

@implementation WebImageOperations


+ (void)processImageDataWithURLString:(NSString *)urlString andBlock:(void (^)(NSData *imageData))processImage
{
    NSURL *url = [NSURL URLWithString:urlString];

    dispatch_queue_t callerQueue = dispatch_get_current_queue();
    dispatch_queue_t downloadQueue = dispatch_queue_create("com.isupport.processsmagequeue", NULL);
    dispatch_async(downloadQueue, ^{
        NSData * imageData = [NSData dataWithContentsOfURL:url];

        dispatch_async(callerQueue, ^{
            processImage(imageData);
        });
    });
    dispatch_release(downloadQueue);
}

@end

And in your 

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath

// Change cell.picImageView to your ImageView
cell.picImageView = [WebImageOperations roundedImageView:cell.picImageView];
// Pass along the URL to the image (or change it if you are loading there locally)
[WebImageOperations processImageDataWithURLString:urlString andBlock:^(NSData *imageData) {
    if (self.view.window) {
        UIImage *image = [UIImage imageWithData:imageData];

        cell.picImageView.image = image;
    }

}];

That will load the images as needed and the TableView will take care of de-queuing them as needed. Thanks

Upvotes: 2

Selvin
Selvin

Reputation: 12493

You have to load the images only when they are in visible frame. If user scrolls away from a loaded image, then you should unload it and release the associated memory. Thats how you will be able to show 1000s of images without getting a crash.

Upvotes: 1

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