iOS Programming Cookbook

How to do it...

To see GCD in action, perform the following steps:

1. Create a new Xcode project with the Single View Application template and with the name GCDDemo.
2. Open Main.storyboard and add an image view with the following constraints in the view controller:

      ImageView.leading = Superview.leading 
      ImageView.top = Superview.top 
      ImageView.width = Superview.width * 0.5 
      ImageView.height = Imageview.width 

3. In the same way, add 3 more image views to be like a grid:

4. Now let's add a slider that will just be used to check whether we did any operation that blocked the UI or not.
5. The final UI of the screen will look like this:

6. Now, let's take ...