Or: how certain languages can stab you in the back with multiple plurals.

Hey, plurals are easy, aren't they? Add an "s" to a noun, and you're done (at least for most regular nouns, that is). In strings design, it would look like this:

"follower_singular" = "1 follower";
"follower_plural" = "%@ followers";

Dead easy. That's all there is to it. 
Really? Not quite, we're afraid.

Do you know Russia? Or Poland? Or the Ukraine? Or Serbia? Or Slovenia? Or Croatia? Or…?
They all have one thing in common: their languages have more than one plural form. And no, we're not kidding!

Russian for example uses one plural form for all numbers ending on 2 to 4 (except 12 to 14), and another plural form for numbers ending on 5 to 9.  And – as if things wouldn't be complicated enough – plural numbers ending on 1 even use the singular form (except 11). Confusing? Indeed! But don’t be scared. We have helped many clients implement these patterns into their code. Get in touch with us and together we'll find a way to master this plurals jungle.
 

Or: how gender issues make a set of strings difficult to localize.

Just as with certain human beings you cannot tell straight away if they're male of female, translators for certain languages desperately need to know what gender your placeholders will have. 

Why? Because their translation of placeholder-related words may differ depending on the placeholder's gender? Want an example? Here you go:

"failed" = "%@ failed";`

If the phrase replacing the placeholder were male, in Italian this would be:
"failed" = "%@ non riuscito"; 

If the phrase replacing the placeholder were female, this would be:
"failed" = "%@ non riuscita";

Now you might ask: what happens when the placeholder could be both male and female? Well, you're screwed. Don't do this. Never. Ever. Ever. Don't even think about it. It'll go wrong. Find some other solution. Now!
 

Would you think that such a small word such as the indefinite article "a" can cause such trouble in localization? Let's have a look at how to avoid this pitfall:

"notification" = "%1$@ sent you a %2$@";
"message" = "message";
"photo" = "photo";
"video" = "video";

Fairly simple. But impossible to translate properly in certain languages!

In German for example "message" is feminine gender and "video" is neutral gender. The thing is, German happens to have different articles for feminine, masculine and neutral gender nouns. So, depending on what type of content is being sent, the "a" in "%1$@ sent you a %2$@" needs to change: EINE Nachricht, but EIN Video.

The solution: Move the article.

"received_notification" = "%1$@ sent you %2$@";
"message" = "a text message";
"video" = "a video";

And voilà, your translators will certainly remain on the light side of the force. But more importantly, you will have a flawlessly localized app.