For the last step, display the weather value. 
In Flutter, FutureBuilder and 
StreamBuilder
widgets are used to display the results of a Future in the UI. 
The following example uses a FutureBuilder:

For the complete example, check out the
async_weather file on GitHub.

Leveraging a background thread/isolate

Flutter apps can run on a variety of multi-core hardware, 
including devices running macOS and iOS. 
To improve the performance of these applications, 
you must sometimes run tasks on different cores
concurrently. This is especially important 
to avoid blocking UI rendering with long-running operations.

In Swift, you can leverage GCD to run tasks on global queues
with different quality of service class (qos) properties. 
This indicates the task’s priority.

func

parse

string

String

completion

@escaping

([