Validating View Controllers with Quick and Nimble

On arriving  UI automated testing in XCode 7 developers had a great tool for automatically validate our apps.  But as our test suite starts growing we start facing some inconveniences.

By using accessibility interface you cannot validate view controller attributes, for instance validate if you got the right number of cells in a collection. Another problem that I faced was at time of refactoring test cycles took to long.

I strongly believe in testing, but dealing with such inconveniences  pushed me to search for another iOS test frameworks. After watching some videos and hearing about them in some conferences I decided to investigate about validating view Controllers with Quick and Nimble.

The aim of this post is just show how to setup Quick and Nimble test frameworks and play a little bit with them.

Quick and Nimble

Quick is a BDD testing frakework that is almost the same as XCTest, but with the additional focus on describing your intent and why you are testing parts of your code.

Nimble allows you to express expectations using a natural, easily understood language.


I have found some difficulties downloading sample projects with the framework integrated. So at the time of writing this posts the XCode that I am using is 7.3.1 and the Podfile content is the following:

View controller undertest

The view controller under test shows a collection of Gremlins with a search bar that will allow to filter them by name.

Simulator Screen Shot 31 Jul 2016 00.33.15


Test are implemented as a regular UN test, so adding a new test is just adding a new UN test file:



As was mentioned before test are implemented as BDD test structure changes a little bit but do not get scared. Lets start  testing the view controller title:

First thing to do is import Quick and Nimble and extend our test class from QuickSpec. beforeEach is the chunk of code that will be execute before each test. Tests itself are implemented by specifying with it.

Another important issue is the call controller.beginAppearanceTransition before each test, this execute viewcontroller lifecycle calls before executing test.

Now lets launch test:


But remember we have to move from red to green. Now, just set the expected title string name and re-run the tests.

The first impression that you experiment with this framework is how easy and fast is execute a battery of test. An how easy is get into view controller internal attributes and methods for validating what is going on.

Let’s test that collection view can show all the expected gremlins

The view controller by default will show a hardcoded set of gremlins for better understanding, but that is not the real case scenario. For validating that the first that we do is just validate that the number of items that can see the collection view are 13, and afterwards we inject an array of 3 items for validating that the new number of items that can see the collection view now is different:

Lets look for more gremlins

But the view controller also allows us search gremlins by name, now lets validate that this functionallity is really working:

An important issue that I want to mention at that point is that or view controller hides the search bar when there are no items. This is very easy to do with this framework, just check .hidden attribute from search bar and that’s all!.

You can download the sample project used in this post here.


With Quick and Nimble you can run a test suit very quickly and this is great for refactoring. On the other hand is direct to have access to view controller internal stuff, this will save you lines of code and execution time on UI testing. So Quick and Nimble is a great alternative to unload test stuff from UI testsuite.


Useful links

Model your classes with Argo JSON parser

The aim of this post is just basic introduction about how to use Argo framework for feeding your model classes from JSON data.

What is Argo.


Argo is a library that lets you extract models from JSON or similar structures in a way that’s concise, type-safe, and easy to extend. Using Argo, you won’t need to write validation code to ensure that incoming data is of the right type, or to make sure required data fields aren’t turning up empty. Argo uses Swift’s expressive type system to do that for you, and reports back explicit failure states in case it doesn’t find what you’ve told it to expect.


Argo is the Greek word for swift and the name of the ship used by Jason, son of Aeson, of the Argonauts. Aeson is the JSON parsing library in Haskell that inspired Argo, much like Aeson inspired his son Jason.

Codoapods. First things first.

In the Podfile you will have to add two frameworks, Argo itself and Curry that is being used for saving effort on initializing structs and classes.


Parsing structs

In this section through different examples I will explain how to parse the most common JSON structures.

Example 1. Most Basic JSON structure.

The content of the json file is the following:

The modeling struct is the following:

Just a few comments

  • As you can see with curry you save up call the initializer passing all class attributes.
  • <^> is for marking the first attribute, the rest are marked with a <*>
  • <| is for parsing a regular attribute and <|? for the optional ones.

For parsing just:

  • “person” is just the filename that contains the json.
  • JSONFromFile is a helper method that retrieves the json from the file. At the end of the post you will find a like for downloading whole sample project.

Example 2. 1-n attributes.

The content of the json file is the following:

The modeling struct is the following:

And this one:

Just a comment:

  • <|| is for parsing a collection of items

For parsing just:

Example 4. Another way of parsing JSON file.

The content of json file is the following:

The modeling struct:

For parsing the struct just:

As you can see the way of calling parser in that case is different but the result is exactly the same.

Parsing classes

For parsing classes I am based on the last struct example, but for clear understanding I will show an example.

This is the json content:

The modeling class:

In deep the idea is quite close than with structures, but in case of classes is carried out in a different way.

Finally for calling the parser:


I hope that throught all those examples you will not find any difficulty for understanting how to do a basic parsing. Please take a look at the library documentation for deeper understanding. You can download the sample project from here.

Usefull links


Break up massive view controllers (Swift)


MODEL-VIEW-ADAPTER DESSING PATTERN. It is quite common in iOS programming that view controllers begin to grow and at the middle of development you discover that you have a view controller class with hundreds or even thousands of line. This is the common scenario where the view controller, apart from dealing with its controllers (uitableviews, uitableviews, hierarchy of views,…), has also to process data for being properly presented attend to notifications.


The aim of this post is to explain an approach for breaking up view controllers into different design classes and provide them different responsibilities for practically leave the view controller with the responsibility of setup its view controller and filling its ui controllers when necessary.

Class design

MVC approach


This approach is the most convenient case that the amount of information that you have to present in the view is quite reduced.

MVA approach



This other is the most convenient when you have to deal with more than one dataSource in the same view controller, and also the origin of the data to show come from different sources (a data base, internet request, some costing data process,…).


View. As always, show the content views.

View Controller. In this approach, setup its uicontrols (tableviews, collection views, a view hierarchy, …) and attend its events. This is not something new, but what is new is that is responsible of being delegate of an Adaptor class and implement its delegated methods. Those delegated methods are basically informing view controller that there is new data to show in the view.

ModelView. Is the model data to be shown in the view.

Adaptor. Is the responsible for starting the processes for retrieving data and providing it to Model Data. Once there is some data to show is provided to viewcontroller via delegate.

AsyncOperation1,…n. Are asynchronous operation for retrieving data from elsewhere. In the worst case scenario this action will take time.

As you can see the View Controller get slimmer by moving part of the code that it performed in MVC approach to Adaptor and AsyncOperation classes.

The template

For proving you that concept you can take this sample project that implements what I have exposed.



Custom uitableview cell in Swift

The aim of this post is to show how to build a Custom SWIFTed TableViewCell view cell. I have found several shallow examples with the default cell. But soon you will discover that will not fit a real sample project situation. I have found several difficulties from moving to Swift, that took me more time than I expected and that pushed me also to write this post.

The custom table view cell

I have just created a new Single View Project Application  in the default view controller  and added a new NSObject class that extends from uitableviewcell.

Captura de pantalla 2015-07-10 a las 18.54.54


Captura de pantalla 2015-07-10 a las 18.56.24


The storyboard

I have added a table view controller and a tableview cell with an image view and a label.

Captura de pantalla 2015-07-10 a las 19.02.50

Now is time to setup the custom table view cell. Firstly the  new  class associated to the cell:

Captura de pantalla 2015-07-10 a las 19.07.15

And secondly set the cell identifier:

Captura de pantalla 2015-07-10 a las 19.07.40

The View Controller

Now it is time for connecting the storyboard with the source code. Lets start off with the main view controller:

I have mapped the tableview to tbvData, and added the minimum uitableview delegates. The table view is filled with 3 elements contained in two arrays (items and images).

The table view cell

In the custom cell I have added an image view and a label as an example. This is the code that  configures the cell:



Captura de pantalla 2015-07-11 a las 14.58.34

You can get also find the code here

Notification mechanism simplified (swift)

The aim of this post is to explain and provide an example about notification mechanism simplified (,but not simplistic) in swift. The first thing that you need to be clear is when to use this mechanism and when delegate mechanism.

Both mechanism help to decouple view controllers. Notifications offer the advantage that multiple objects can observer one notifications.  In delegate mechanism the communication is direct (through a protocol method implementation) with the delegate class.

The example that I am going to present to shows the notification mechanism as a broadcast service. A timer periodically will launch a notification, on the other side there will be two classes (Alice and Bob) that will be intercepting the message.

As you can see in the code every 3 seconds is sent a notification that is intercepted by Alice and Bob class in the following way:

Is important to keep under control when to unsubscribe to the notification mechanism. In case of Alice is after receiving 3 messages and in case of Bob is when the class is removed from memory.

Once we run the project we should have to see the following in the log window:


You can find the sample project here.