ios newsfeed blur 2.m

self.text = self.event.text;
__weak id wself = self;
NSString *imageUrl = self.event.imageUrl;
self.image = nil;
self.overlay.image = nil;

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    UIImage *image = [ImageCache sharedCache] get:imageUrl];

    if (!image) {
        image = [[wself downloadImage:imageUrl] scaleWithWidth:cellWidth];
        [ImageCache sharedCache] put:image withKey:imageUrl];
    }

    UIImage *blurredImage = [ImageCache blurredCache] get:imageUrl];

    if (!blurredImage) {
        blurredImage = [image blurRect:overlayRect];
        [ImageCache blurredCache] put:blurredImage withKey:imageUrl];
    }

    dispatch_async(dispatch_get_main_queue(), ^{
        // skip if the cell’s event has changed
        if (![imageUrl isEqualToString:wself.event.imageUrl]) {
            return;
        }

        wself.overlay.image = blurredImage;
        wself.image = image;
    });
});