Question

Almost every ios app now has something like “Feed” option.
Programming that usually includes fetching images from the web, caching them, handling pages, “pull to update option”, etc. – all the standart stuff.

But looks like there is no standart solution for that?

• I tried “three 20” – really big, complicated library with many modules. It really lacks good documentation! And it also had “slowdowns” while fetching images from cache.

• Maybe I should use different small libraries for each small task separately? Like HJCache, EGO, etc.

• Or is it better to write everything from scratch without any libraries?

Please give me advice on best practices here, i am really stuck now.

Answer 1

This one is very easy to drop in for pull to refresh.

For image loading, I wrote the following category for UIImageView:

// .h
@interface UIImageView (UIImageView_Load)
- (void)loadFrom:(NSURL *)url completion:(void (^)(UIImage *))completion;
@end

// .m
#import "UIImageView+Load.h"
#import <QuartzCore/QuartzCore.h>

@implementation UIImageView (UIImageView_Load)

- (void)loadFrom:(NSURL *)url completion:(void (^)(UIImage *))completion {

    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    [NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
        if (data) {
            self.image = [UIImage imageWithData:data];
            if (completion) completion(self.image);
        }
    }];
}

@end

// To use it when building a cell

//...

MyModelObject *myModelObject = [self.myModel objectAtIndex:indexPath.row];
if (myModelObject.image) {
    cell.imageView.image = myModelObject.image;
} else {
    NSURL *url = [NSURL urlWithString:myModelObject.imageUrl];
    [cell.imageView loadFrom:url completion:^(UIImage *image) {
        // cache it in the model
        myModelObject.image = image;
        cell.imageView.image = image;
    }];
}

// ...