Loading images in background to optimize the loading in ios

Question

I am trying to optimize the load in my application, in fact, I have a lot of images that loaded in my application, and I spend a lot of time waiting for a view controller to ope

Answer 1

Here is a slightly modified approach of Ramu Pasupoletis answer. I added the __block modifier to make the var img visible inside the block called on the main thread. Here is the complete method definition which I use in

-(UITableViewCell*)cellforRowAtIndexPath:(UIIndexPath*)indexPath;

for fetching the thumbnails lazily. I also added placeholders there for the cells UIImageViews.

//lazy loading of thumbnails for images in cell via bg thread
-(void)loadImageForCell:(CustomEditTableViewCell*)theCell withFilepath: (NSString*)filepath{

dispatch_queue_t q = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
dispatch_async(q, ^{
    UIImage (__block *img) = [UIImage imageWithContentsOfFile:filepath];
    UIImage *thumbnail = [[GlobalFunctions sharedGlobalFunctions] imageOfSize:CGSizeMake(40, 40) fromImage:img];
    dispatch_async(dispatch_get_main_queue(), ^{
        theCell.imageView.image = thumbnail;
    });
});
}