Downloading an image into UIImageView

Downloading an image into a UIImageView is a common task. UIImageView doesn't support setting an image URL; it expects you to download the image in a background thread, optionally cache it, and set the image property of the UIImageView.

To make this process easier, there are many libraries that have added a category method to UIImageView to automatically download, cache, and set the image.

Add AFNetworking to the project

Add AFNetworking to the project by downloading it here (click on Download ZIP on the right toolbar). Open the AFNetworking folder and drag the subfolders called AFNetworking and UIKit+AFNetworking into your project. Be sure to click "Copy items into destination folder".

Using UIImageView+AFNetworking

In the file that has your UIImageView, import the UIImageView+AFNetworking category.

#import "UIImageView+AFNetworking.h"

Then, simply use the method that AFNetworking adds to UIImageView.

NSURL *url = [NSURL URLWithString:@"http://
[imageView setImageWithURL:url];

// Or, optionally set a placeholder image to use while the image is downloading

[imageView setImageWithURL:url placeholderImage:placeholder];