[entity345]

Bopomofo has nothing to do with Taiwan, specifically.

It's a system introduced by the Republic of China, and tha continues to be used in the Republic of China (only Taiwan left these days).

That's because the mainland switched to Pinyin in the 50s.

That being said, Taiwan has now also officially switched to Pinyin so use may increase.

Edit:

Another interesting, and old, system to write Mandarin using the Arabic alphabet: Xiao'erjing: https://en.wikipedia.org/wiki/Xiao%27erjing

Edit 2:

Bopomofo is in the same line as Hiragana/Katakana/Korean system: It simplifies and make things phonetic but still creates a brand new characters set inspired by Chinese characters.

With Pinyin, to me the main development was to integrate that there was already an ubiquitous alphabet in existence, the latin alphabet, that could be used and save the trouble of yet another writing system.

A bit like what happened in Vietnam (though obviously that's because a Frenchman came up with the system).

[FabHK]

For what it's worth, there is also a Sinitic language fairly close to Mandarin that's written in Cyrillic characters, Dungan (which, incidentally, sort of refutes the notion that one can only write Chinese languages with Chinese characters).

https://en.wikipedia.org/wiki/Dungan_language

http://languagelog.ldc.upenn.edu/nll/?p=4578

[juiyout]

As a resident here, I know for a fact that Taiwan did not replace bopomofo with pinyin.

You see bopomofu is to denote pronunciation not to romanticize characters. If you are talking about how location/street names are spelled, some form of pinyin (literally means spelling) had always been used for romanticization.

[philliphaydon]

Bopomofo is still taught in taiwan and zhuyin is still used for typing. The only thing changed is signs now use pinyin....

[entity345]

It's a start...

[philliphaydon]

Well they don't change the signs in Tainan or Taipei, only exists in 1 or 2 county's.

Hopefully they don't switch to pinyin, and I especially hope they don't switch to Simplified.

[juiyout]

It had always been some form of romanticization for street names. Pronunciation has always been bopomofo.