View controllers have a central role in iOS apps and build the skeleton of every app you make. This is because each screen of the app is represented by a single view controller. Because of this central role they have, they are at the center of a lot of activity and perform many duties during their lifetime.

Since the introduction of Swift, optionals seem to have used a lot of confusion for people learning the language. I have to admit that at the beginning it took me a while too to wrap my mind around them. The cause was that I didn’t take the required time to fully understand them.

iOS apps are built according to a widespread programming pattern: the model-view-controller pattern (or MVC). The MVC is a high-level pattern used to describe the global architecture of an application and to classify objects according to the general roles they play. In MVC objects tend to be more reusable and programs are more easy to change.

In this last part of the guide, we are going to have a look at blocks and how they work.

Table of contents

What blocks are useful for
Declaring and using blocks
Passing blocks as parameters to methods
Capturing the context
Blocks and memory management

After seeing how classes and objects work in Objective-C, this part will be completely dedicated to types in Objective-C. This feature comes straight from C, but it’s still extensively used in Objective-C programming, including Apple libraries. Since you will encounter this quite often, it’s worth to spend some time having a look at this feature.

Table of contents

Defining custom types
Constants and enumerations
Bitwise operators and bitmasks
Structures

Now that we know how to create our own classes, we will go over some useful features of the languages to deal with the organization of class interfaces and memory management.

Table of contents

Categories
Protocols
ARC and memory management

After seeing in the second part of this guide how to create and use objects, now we will see how we can create our own classes.

Table of contents

Classes
Headers, importing and forward declarations
Properties and instance variables
Initialization