How to implement social sharing in your iOS app (Twitter and Facebook)


Just yesterday I implemented social sharing in my new app called Sigma. Here is how I did it in two easy to follow steps.

First, I added Social.framework to my project and imported it to my view controller.

Second, I wrote this code for Twitter (it’s in Swift 3.0):


And this code for Facebook:


That’s it!


How to add custom fonts to your Xcode project

To add custom fonts to your project you need to go through a few easy steps.

First, download the fonts you need. Usually, they are .ttf or .otf files. Drag and drop the files to the Project Navigator. It is best to put them all in one group named Fonts.


Go to project’s Build Phases and make sure the files are included in Copy Bundle Resources.


Then go to your Info.plist file and add the file names to the array called Fonts provided by application.


At this point you can use your new fonts in your project. But there is one more thing, though. To use the fonts programmatically you need to know their names. Their names are not the same as the names of font files you just included into your project. Filenames can be anything ending with .otf or .ttf. Font names on the other hand look like these:

BebasNeueBold, BebasNeueBook, BebasNeueRegular, BebasNeue-Light, ProximaNova-Regular, ProximaNova-Bold, ProximaNova-Light, HelveticaNeue-Light, HelveticaNeue-Bold, CenturyGothic-Bold, CenturyGothic, MyriadPro-Regular

So, how do you know the proper font names? Just print all the font names to the console. Use this snippet:



Transparent navigation bar snippet

Put this code into viewDidLoad method of a view controller where you want to have transparent navigation bar.

Swift 3.0





How to resolve assets error in Xcode 8

Recently I started seeing this error:

Invalid Bundle – The asset catalog at ‘Payload/XXXXX/’ can’t contain 16-bit or P3 assets if the app supports iOS 8 or earlier

When I saw it in my own app I just changed the deployment target to iOS 9.3. Next time I saw this error in the project that I do on my job. This time the client wanted to keep supporting iOS 8.0 so I had to find another solution. After googling for some time I found the solution here.

The rest of the post is just a copy-paste. I need it here on my site, so I don’t have to look for it again later.

1. Create an Inspectable .ipa file.  In the Xcode Organizer (Xcode->Window->Organizer), select an archive to inspect, click “Export…”, and choose “Export for Enterprise or Ad-Hoc Deployment”. This will create a local copy of the .ipa file for your app.

2. Locate that .ipa file and change its the extension to .zip.

3. Expand the .zip file. This will produce a Payload folder containing your .app bundle.

4. Open a terminal and change the working directory to the top level of your .app bundle

cd path/to/Payload/

5. Use the find tool to locate files in your .app bundle as shown below:

find . -name ‘’

6. Use the assetutil tool to find any 16-bit or P3 assets, in each your application has as shown below. :

sudo xcrun –sdk iphoneos assetutil –info /path/to/a/ > /tmp/Assets.json

7.  Examine the resulting /tmp/Assets.json and look for any contents containing “DisplayGamut”: “P3” and its associated “Name”.  This will be the name of your imageset containing one or more 16-bit or P3 assets.

8.  Replace those assets with 8-bit / sRGB assets, then rebuild your app.

Update:  If your Deployment Target is set to either 8.3 or 8.4 and you have an asset catalog then you will receive this same error message, even if you do not actually have 16-bit or P3 assets.  In this case you will either need to lower your Deployment Target to 8.2, or move it up to 9.x.


How to prevent double tap on UIButton

If you Google this question you will get a lot of wrong answers, which may be marked as right answers on Stackoverflow. The simplest “solution” is to disable the button temporarily inside its action method.

For instance:

But from my experience this approach doesn’t work. The reason is that UIKit framework doesn’t perform your commands immediately: it decides on its own when the right time to do what you ask it to do is. I read about it somewhere a long time ago and I don’t have any links now, so feel free to correct me if I’m wrong. But that’s what I have encountered many times in my work. And it’s strange that nobody on the internet is talking about it. That’s why I wonder if I overlooked something, but anyway…

Here is the solution that I use. I create a BOOL variable or a property on my view controller. Then I just use this flag instead of enabled property of UIButton.

Of course, you must enable the button later by setting the BOOL variable to NO.


How to free a lot of space on your development Mac computer

Since about a week ago I started working from home. I used to work on a powerful iMac at the office but now the only computer that I use for iOS development is my MacBook Air 13” (early 2014). I also have a monitor and a wireless keyboard. My setup looks something like this.

Everything is well and good, my laptop is powerful enough for my programming work. There is only one thing I don’t like about it: its HD is only 120 Gb so it runs out of memory all the time. Or, used to run out of memory until I figured out how to free a lot disk space.

First of all I installed a program called Disk Inventory X, which allowed me to analyse my disk space usage. Then I found out that the most memory consuming thing on my computer was this folder

~/Library/Developer/Xcode/iOS DeviceSupport

It weighs many gigabytes (it weighed tens of gigabytes when I first found it) and they say that it is perfectly safe to delete everything from this folder. Now whenever I feel like I don’t have enough space I clean this folder.

There is also one other folder that rapidly eats up the disk space.


Every time you build an archive in Xcode it ends up in this folder. The archives for some of the apps I work on take more than 100 Mb. Some days I can make quite a few of these archives. Now I remove the older archives from time to time. Just recently I freed 10 Gb on my computer this way.

By the way, the whole purpose of this post is to remind myself of the location of these folders, so I don’t have to look for it in the future.

Another thing I did: I bought a 1 Tb external hard drive. I use it for storing my photos, movies and backing up my documents. I don’t store any photos on my MacBook any more and I even switched off iCloud sync so that the photos I take on my iPhone don’t automatically end up on my computer. I just move my photos from my iPhone to the external drive manually from time to time. 

Now at any time I have at least 20 Gb of free space on my computer which is pretty comfortable for me and I don’t need to buy another computer which is super good.


Creating an email subscription web service (Part 2)

In the previous post of this series I decided what tables I’m going to have in my database. I created those tables (people_table, lists_table, subscriptions_table) using Workbench. Then I had to spend one evening trying to fix an issue with Russian language in MySQL. I just couldn’t save entries to the database, if those entries had Russian symbols in them. I was trying to find a solution that would fix this issue once and for all, like maybe changing some setting in MySQL or in Workbench. But I couldn’t.

So, for now the only way for me to use Russian symbols in my database is to set the collation of each table at the time of its creation to utf8-default. If the table already exists and it has wrong collation, I don’t know how to change it. If you know how to set text encoding globally in MySQL, please, tell me in the comments section below.

I have read something about JavaMail and about setting up a mailing server in general. It all seemed complicated, so I’m not sure if I’ll ever complete this project. I will definitely read some more on this topic, though. For now, I decided to do without the mailing part of an app. What I want to do now, is create a web form with two fields – name and email – and a server side which will get the information from a web form and save it to the database.

So, I created the form. This is what it looks like.


And here is its source code.

Notice the third input – list_id. It has type “hidden”  so it isn’t visible on the page, but the value of the list_id parameter will be sent to the server. This is how the server will know which list the user is subscribing to. The value of this parameter is set manually for now. 

I also created a Web Project in Eclipse called EmailSubscriptionService. To use JDBC in it I downloaded Connector/J from

I needed to put the mysql-connector-java-5.1.39-bin.jar file from the archive somewhere into my project. I didn’t know what the right place for it was, so I just put it into WebContent/WEB-INF/lib folder. I’m almost sure (after googling a little) that it is not the best place for this file. But it works, and that’s what is most important for me right now.

I created two files: and Then I spent two evenings coding. Finally, I have all the main functionality. I can add people to the list from the web form.

This is my file:


And this is file:


This is my lists_table with just one list in it:


After I get the request from the web form I first check if the list with a specified id exists. Just in case.

Then I add a person to the people_table, if that person is not already in the table, which can be checked by the email: each email is unique in the people_table.


After that I get the person_id from the table and add it to the subscriptions_table along with the list_id, which is 1 all the time (it was hardcoded into the web form, as I showed above). This is my subscriptions_table:


What’s next

Since I am more interested in learning databases (and a little bit of web development) than in learning the mailing stuff, I will postpone the learning of JavaMail until better times. Instead, I will create an admin panel for my app. It will allow me to see my lists of subscribers from the browser.

To be continued.


Adding servlet-api.jar to Eclipse project

As you may know, if you have servlets in you Java project you need to add servlet-api.jar to you Web App Libraries. Since I don’t work in Eclipse very often, I always keep forgetting how to do it. So, here is a short instruction with pictures.

Go to Web App Libraries/Build Path/Configure Build Path…


Click Add External JARs…


Find and choose the servlet-api.jar file. It should be located in the lib folder of your Tomcat. In my case the path to the file is:



Implementing a Custom URL Scheme (iOS)

Somebody asked me to add a custom URL scheme to my app, so that they could open the app from a launcher. Before that, I had only done it once, so it took me some time to Google this topic and remind myself of how it’s done.

This post will serve as another memo for me. This is how you add a custom URL scheme to your app:

Defining your app’s custom URL scheme is all done in the Info.plist file. Click on the last line in the file and then click the “+” sign off to the right to add a new line. Select URL Types for the new item. Once that’s added, click the grey arrow next to “URL Types” to show “Item 0”. Set your URL identifier to a unique string – something like com.yourcompany.yourappname.

After you’ve set the URL identifier, select that line and click the “+” sign again, and add a new item for URL Schemes. Then click the grey arrow next to “URL Schemes” to reveal “Item 0”. Set the value for Item 0 to be your URL scheme name.

The quote and the image are from this site.


Developer’s guide to learning design (and Photoshop)

Here are my thoughts on how one can start learning UI design.

For a very long time I thought that I don’t need to learn design. Or, more precisely, I thought that I must not learn design, because I’m a specialist, and specialists don’t waste their time on things that are outside of their domain of expertise.

But the thing is, I’m interested in design. As far as I can remember I always loved to draw, and I believe I do have at least some artistic abilities. Also, it seems so cool to be able to design and then develop you own apps from start to finish. Nothing hinders your creativity. You don’t  just implement other people’s ideas, you come up with your own ideas, and everything you create is truly yours.

So, I decided to at least try to learn something about design. Maybe I’ll get serious about this design thing one day. And maybe it will not be that bad. Yes, if I do it for real, I might be spreading myself to thinly. But on the other hand, what if I become one of those mythical creatures called unicorn developers? Wouldn’t that be cool?

Learning design is a lot like learning programming

Anyway, for now I’m just learning the basics. More specifically, I decided to learn Photoshop. I have already spent several evenings learning Photoshop, and here is what I have found out.

Learning design is a lot like learning programming. At first I didn’t know where to start, and I thought that maybe I needed to buy a course on Photoshop. But then I decided to take the approach I used for learning programming. And it worked.

First of all you need to learn how to use the tools. To do it you just draw something. And when you try to draw something in Photoshop, you are going to have lots of questions. When you have questions, just Google them. That’s how you learn design. And that’s how I learned programming. There is no need to buy any courses.

What to draw? Don’t try to create at first. Just copy. I believe it is very important, and here is why. If you try to create something as a beginner, you creativity will be hindered by you lack of ability. So you will end up producing something too simple and too ugly. You might have a great vision inside your head, but then you will have to simplify it and distort it to match your limited abilities.

On the other hand, if you just forget about creativity for a while, and concentrate on copying stuff, that will enable you to develop your abilities. This way you know exactly what you are trying to achieve, and you just do whatever it takes to recreate someone else’s design. Your newly developed skills will let you be creative later.

The best way to start with this approach is to go through some tutorials. Here are the tutorials I used.

Tutorial 1Tutorial 2Tutorial 3.

And this is just one example of what I ended up with:


Tutorials are good, because they tell you in great detail, what you should do. I think it is the best way to learn different tools in Photoshop.

I plan on going through a couple more tutorials. Then, the next step is to find a design that I like and try to copy it. This time without a tutorial. Then I will do it for many times for different designs.

Notice, how it is exactly the same as learning programming. In programming you too go through a bunch of tutorials at first. Then you create a bunch of your own apps. Only after that you read books and go through courses.

Other things I discovered

When it comes to mechanical skills of a designer (like ability to use Photoshop) I believe they can be all divided into two big areas.

One is all about rectangles and texts. Seriously, while going through the tutorials, that was all I was doing: drawing rectangles and texts. Now, when we talk about text, there is this thing called typography which is an entire field of knowledge in its own right, and there is a lot I can learn there. But for now I like to think about texts and rectangles as being two parts of one skill set which is all about placing stuff on the screen.

Note, that here I’m only talking about the mechanics of design process. There is a difference between knowing how to place stuff on the screen and knowing where to place stuff on the screen. I’m not even starting to think about learning the latter part just yet.

The second area (or a skill set) is all about illustrations. This one I haven’t yet started to learn. But I think it can be learned the same way, through tutorials. In this case the tutorials don’t need to be necessarily focused on UI design. They can be more general and focused on little things, like, for instance, how to draw a semicircle, or a sector. Stuff like that. Also I know that designers like to use other people’s artwork when it comes to icons, so maybe learning how to do illustrations is not that crucial for a UI designer.

There is also a funny little thing I have learned. Usually, when designers give me their designs so that I can start developing an app, I often notice that they misspell words. Like all the time. And over time that lead me to believe that maybe designers as a species are sort of not very bright people, to put it mildly.

Now, when I started learning Photoshop I discovered the real reason for designers’ ‘illiteracy’. It turned out that Photoshop doesn’t have a spell checking capability (or at least I haven’t found one). BTW, can you find a typo in the picture in this post? I didn’t make it on purpose.