CODEWITHSUNDEEP
objective-cuitableviewmemory-managementuiimageuicollectionview
Carl Taylor
Carl Taylor

Reputation: 101

UICollectionView / TableView Memory Allocation Issue with Base64 images

I have a UICollectionView / UITableView showing images, as I scroll through the images the memory allocation gradually grows and eventually crashes my device.

To create my objects for the UICollectionView / UITableView I have a builder class where I generate my objects from JSON (Included in this JSON is a Base64 string of an image). After creating these objects I put them into an NSArray and then pass them to the UICollectionView / UITableView.

The memory allocation issue happens when (in the builder class) I create my UIImage from Base64:

NSData *dataFromString = [[NSData alloc] initWithBase64EncodedString:base64 options:0];
UIImage *image         = [[UIImage alloc]initWithData:dataFromString];

But if I create my UIImage from a png/jpg (again in the builder class) I have no issues (i.e. the memory allocation does not grow):

UIImage *image = [UIImage imageNamed:@"image.png"];

I used instruments and there appear to be no memory leaks, and when I dismiss the UICollectionView / UITableView the memory footprint goes down, but Im at a loss as to why the difference seems to be the use of Base64.

Thanks in advance

Carl.

Upvotes: 0

Views: 379

Answers (1)

Carl Taylor
Carl Taylor

Reputation: 101

I solved this issue by creating a tempFileManger class, I then write the UIImages to a temporary directory as PNG:

 NSString *path = [tempDir stringByAppendingPathComponent:imageObject.title];
 NSData *data   = UIImagePNGRepresentation(imageObject.image);

Then in my cellForItemAtIndexPath method I retrieve using the following:

NSString *path = [tempDir stringByAppendingPathComponent:imageObject.title];
UIImage *image = [UIImage imageWithContentsOfFile:path];

Once I have finished using the images I delete all the images in the temp folder using my tempFileManagerClass.

   NSArray *contents = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:tempDir error:nil];

    for (NSString *filename in contents)  {
        [[NSFileManager defaultManager] removeItemAtPath:[tempDir stringByAppendingPathComponent:filename] error:NULL];
    }

Upvotes: 0

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