Technically I started work on my 2016 challenge late 2015. The goal remains to have something tangible done as the year progresses. This brings me to foundation of all I intend to build: The Architecture.

As a Software Engineer, I deal with Architecture decisions daily. Making best guesses on future design and ruminating on past bad decisions. In the Agile landscape I have come to terms with that fact that Architecture is really where you land and the initial key decisions are around mitigating risks. How much time one puts in upfront architecture decision depends on what you are building: A shed or a skyscraper. In my case I choose to land somewhere in between.

I typically advocate for a factor of 3 to account for the smallest unit of complexity. In this first round I was focused more on simplicity which meant a single node and single broker where possible.

My current tech-stack includes:

• MQTT
• Kafka
• ELK Stack
• Cassandra
• 1 Linux box
• Programming language choice –  Python
• Sensor Peripherals (Efergy Electricity Monitor and R820 Tuner)

Here is my view from Kibana

Networking in the mobile context largely entails communicating with external entities over the internet. Like most modern web or mobile platforms today iOS supports HTTP.

These network requests are referred to as ‘Tasks’ in the iOS world and there are three basic network tasks you can perform using the NSURLSession API

Data Tasks – These are network tasks where you exchange simple data which typically get stored in memory as a NSData object during server interactivity

Download Tasks – These tasks involve retrieving the contents of a url as a temporary file from a server (supports running as a background activity)

Upload Tasks – These tasks handle similar messages as the download tasks just in the opposite direction by uploading files to a server (also supports running as a background activity)

This API is asynchronous and provides what some might liken to callbacks in Javascript. The example below is a data task (indicated by ‘dataTaskWithRequest’)

‘in’ signifies the beginning of the completion handler block. This call can’t actually be kicked off without calling resume method on the task

data refers to the actual data you expect back and looks like byte stream data when you get the service response. This needs to be deserialized which you can do like below

response gives you details about your response such as status code and such

error gives you detail if there is an error. If there is none you can expect it to be nil. data is nil if an error is returned

This is not the all in all you need to know on iOS networking but at the very least it should give you a thousand foot view of what you need to know make very common network calls in iOS using Swift.

One last point to note. By default iOS limits regular HTTP calls favoring HTTPS calls out of box. So you need to account for extra steps to support network calls to urls that are prefixed with basic HTTP.

Assuming you figured how to play an audio file in Swift, now you want to play with the speed of the audio. The rate property of the AVAudioPlayer object is what you need to change up the speed. The catch is that you need to set the enableRate property to true before you can actually do this.

In this example I create a helper function to set things up. audioPlayer is my instance of AVAudioPlayer. I set currentTime in my use case to start the audio from the beginning. It is also a good practice to stop the audio before playing.

Then I call that function in my actions

That’s it mainly.