macOS Programming Tutorial: Working with Alerts, Sheets and Modal Windows

One of the basic, yet vital things a developer should know when creating macOS apps is how to present alerts, system panels or custom windows to their apps. Regardless of how small or big an app is, it will always be necessary to display an informational message to the user or ask for confirmation. Letting users to search for and open a file from their drive is the case for many kinds of apps, as well as saving back to disk.
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Documenting Your Swift Code in Xcode Using Markdown

Amongst all the features Xcode 7 incorporates, there is one that admittedly distinguishes; that is the new revolutionary, much better way to write code documentation. With the introduction of Xcode 7, developers can use the powerful Markdown syntax to apply rich text formatting to the text of their documentation, which in combination to specific keywords that indicate special parts (like parameters, function results, etc) can result to an amazing outcome. The new Markdown-enabled documentation style, as the new one has several advantages: It provides greater level for customizing the text, it’s more flexible, and of course, more interesting. However, if you’re still interested in the old-style documenting style, take a look in our previous tutorial.

Documenting the code is an extremely important task for every developer. Even though it seems that it stalls the development process, it’s actually a part of it. I won’t disagree that writing proper and comprehensive documentation for every single property, function, class, struct, or anything else that exists in a project is not an easy job. However by writing the proper documentation you can:

  • Describe the purpose of the properties, functions and classes up to the level of detail that you desire. Moreover, it’s the best place to highlight specific conditions, cases or requirements for your functions that have to be noted somewhere.
  • Highlight the input and output (parameters and return values) of your methods.
  • Remember without any hassle what each function is meant to do and what each property is for when you revisit a project months after its initial implementation.
  • Make it easy for other developers to understand how to use your code when you share it or make your own libraries.
  • Produce professional-looking manuals using tools made for this reason (for example Jazzy).

The code documentation you write in Xcode can be previewed and accessed in three different ways:

  • By Option/Alt-Clicking to the name of a property, method, class, etc. The Quick Look preview will pop up right above or below the name.
  • By placing the cursor in the property, method or class name, and opening the Quick Help Inspector.
  • By using third-party tools that will produce a manual for you. For example, Jazzy is such a tool, and we’ll discuss about it later on. By using it, your documentation is compiled in webpages and all together consist of a standalone website that is being created as a subfolder inside your project’s folder.

Code documentation is not made of stone; it has to be fluid and change according to modifications being made in the respective entities (properties, methods, classes, structs, enums). It’s almost a rule that if you don’t add the documentation by the time of the implementation of a new entity, then it’s almost certain that you’ll never do it. Therefore, try to get used to the habit of documenting your code in the proper timing, and give it any additional time it requires so you make it proper. It worths it.

Continue reading my tutorial on Appcoda

How To Create an Expandable Table View in iOS

A common feature of almost all apps is the fact that they provide multiple view controllers to users to navigate and work with. Those view controllers can be used in many ways, such as to simply display some kind of information on-screen, or to gather complex data from user input. Creating new view controllers for different functionalities of an app is often mandatory, and several times a little bit daunting task. However, sometimes it’s possible to avoid creating new view controllers (and their respective scenes in storyboard) if you just make use of expandable tableviews.

As the term suggests, an expandable tableview is a tableview that “allows” its cells to expand and collapse, showing and hiding that way other cells that in any other case would be always visible. Creating expandable tableviews is a nice alternative when it’s required to gather simple data, or to display on-demand information to users. With them, it’s not necessary to create new view controllers just to ask users for data that in any case should exist in one, default view controller. For example, with expandable cells you can show and hide options of a form that collects data without having to leave that view controller at all.


Whether you should use an expandable tableview or not always depends on the nature of the app you develop. However, as the UI of the cells can be customized by subclassing the UITableViewCell class and creating extra xib files, the look and feel of the app should normally not be a problem. So, at the end, it’s just a matter of requirements.

In this tutorial I’m going to show you a simple but efficient way to create expandable tableviews. Note that what you’ll see here does not consist of a unique method for implementing such a feature. Pretty much the implementation is based on the app needs, but my goal here is to present a quite general way that can be reused in most cases. So, by having said that, move to the next part to get a taste of what we’re about to deal with in this tutorial.

Continue reading my tutorial on Appcoda

A Beginner’s Guide to NSDate in Swift

If I was ever asked what’s one of the most common stuff I do among all projects, then I would have answered that dealing with dates is definitely one of them. Undoubtably, there’s no developer out there who doesn’t really need to “play” with the NSDate class and handle dates in some manner, no matter how much or little the work on dates is. From simply converting a date value into a string up to performing calculations with dates, there’s always one constant fact: Developers have to be acquainted with this side of programming in iOS. It’s not hard to master, and eventually can lead in gaining time in other more important programming tasks. Working with dates might seem like a hassle to new programmers; however that’s not true. All you need is to get the grasp of it.

The most common operation when using date (NSDate) objects in applications, is to convert them into string objects so they can be properly formatted and shown to the users. Quite common is the reverse action as well; converting strings to date objects. However, these are not the only tasks regarding dates. Here’s a sample list of what else can be done when messing with dates:

  • Compare dates.
  • Calculate dates in the future or in the past, simply by using a reference date (e.g. the current date) and adding or subtracting periods of time (days, months, years, etc).
  • Calculate date differences (e.g. find the elapsed time between two specific dates).
  • Break a date into its components and access each date part separately (day, month, etc).

All the above, including the conversions to and from strings, are subject for discussion in this tutorial. Through the next parts, you’ll see that is actually easy to do whatever you wish with dates, as long as you know what your tools are and how you should use them.

For your reference, I give you next a list of links with some important documentation. Don’t forget to pay a visit in case you need more information on specific topics:

Continue reading my tutorial on Appcoda

Documenting Your Objective-C and Swift Code in Xcode with HeaderDoc and Doxygen

During the development of an application there are various steps involved in the whole process. Some of them are the definition of its specifications, the creation of graphics, the implementation, and the testing phase following the implementation. Writing the code maybe consists of the most important part, as this brings the application to life, but further than that, equally important is the proper documentation of the code. No matter how well-written the code is, if there’s lack of a good documentation accompanying it, future troubles it’s possible to arise. Unfortunately, many developers overlook or ignore the importance of the code documentation, and that’s really bad, as good software is not just good code. It’s more than that.

When talking about documentation, apparently I don’t mean just to add a few lines of comments somewhere in the implementation files. It’s definitely more than that. But first, why is it such a big deal to document the code? Well, there are two cases: Whether you’re working on your own, or you are a part of a team. Let’s see in short each one.


If you are the only developer of the under-development application, then it’s reasonable to believe that writing code documentation costs in time, so skipping doing that will bring you right into your target much sooner. Additionally, it’s easy to convince yourself that as you’re the sole developer there’s really no need to do that. But trust me, that’s the worst decision you might make during the app creation period. Suppose that you successfully implement the application, you sell it either on the app store or in a client of yours, and then you put it in the shelf. And after six months or so, you must create a new version of it by adding new features. When you open the project again and look to the existing code, a long before you write the first new line, you realize one killing truth: That you don’t remember almost anything! It’s hard to remember what you did, how you did it, and why! You must follow the one, painful way to wake that project up in your mind, which is no other than taking the project from the beginning and trying to “decode” your implementation line by line. Just a few comments here and there are not helpful, and eventually you end up making a super-effort for a long time until you understand everything. Many of you that you are now reading these lines may have come to that point, and I ensure you that there were times that I’ve been there too. This case is a real nightmare, and you often want to start building the project from scratch. And of course, the scenario described here would just be a… scenario, if we all invested a little time to write proper code documentation.

Read the full tutorial on Appcoda

Introduction to Objective-C Blocks

In programming, what differentiates a good developer from a great developer is the way each one takes advantage of the programming tools he or she offered by the used language. Objective-C, the official language for developing applications for iPhone, iPad and Mac OS, is a multi-featured one, and as a relative to C, very powerful. New developers have a lot to explore when starting working with it, while advanced programmers have always something new to learn, as there are numerous supported programming aspects. One of them, is the capability to write code using Blocks.

Blocks do not consist of a new programming discovery in Objective-C. They exist in other programming languages too (such as Javascript) with other names, such as Closures. In iOS, they first-appeared in version 4.0, and since then they’ve known great acceptance and usage. In subsequent iOS versions, Apple re-wrote or updated many framework methods so they adopt blocks, and it seems that blocks are going to be partly the future of the way code is written. But what are they all about really?

Well, a block is a self-contained, autonomous code fragment, existing always into the scope of another programming structure, as for example the body of a method. The code on the block can “interact” with the world out of it, but what takes place in the block is not visible to the scope out of it. Also, blocks can modify the values of variables being out of its body using a special way (we’ll see more later). Blocks have two great features:

  1. They can be executed in a later time, and not when the code of the scope they have been implemented is being executed.
  2. Their usage leads eventually to a much cleaner and tidier code writing, as they can be used instead of delegate methods, written just in one place and not spread to many files.

Read the full tutorial on Appcoda