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iOS

Posted by Marc Zovighian
Marc Zovighian
1,664 Points

Did anyone complete the last Extra Credit for the Blog Reader course? (Asynchronous requests)?

This was the last Extra Credit:

"Make a multi-threaded version of the Blog Reader app. Currently, the JSON request is being made on the main thread which makes the user interface unresponsive. Create a multi-threaded version of this app so that it parses and loads the JSON data in a separate thread without blocking interaction with the main UI.

Hint: You can use AFNetworking to make an asynchronous request.

In addition, use SDWebImage to download the images asynchronously."

I have absolutely no idea how to do it

2 Answers

Jason Wayne
Jason Wayne
11,688 Points

Basically, AFNetworking and SDWebImage are frameworks that you can install into your project. They are not in-built in Xcode, and you can check them out more in the Github on how to install these frameworks. Or you can install them via Cocoapods.

But if you are just looking to not block the main thread, you can consider using Grand Central Dispatch (GCD) or NSOperation. GCD should be much easier to implement as it is lightweight.

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

// this is the part where you will get do all the connectivity to the JSON and retrieve data

// this is basically moving to the background thread, so that it doesn't do the heavy task on the main thread to block the UI

// check out Apple's Doc about Dispatch_Queue (there's more to than just default such as High and etc..)

    dispatch_async(dispatch_get_main_queue(), ^{

// this is the part where you update your UI (labels and etc..)

    });

Hope that helps! =]

Jason Wayne
Jason Wayne
11,688 Points

Not sure why is the grey background color appearing. Just to clarify, in the scope of the block (in between the 2 grey background color), that's where you update your UI, which is done on the main thread once you have done the heavy task in the background.

Marc Zovighian
Marc Zovighian
1,664 Points

Thanks a lot man!

Sonam Wangyal
Sonam Wangyal
2,208 Points
Sonam Wangyal
Sonam Wangyal
2,208 Points

I don't understand the benefits of the Extra Credit, could you please explain it. Please and thanks! :)