According to the latest update of the Tiobe index, Objective-C is not the third most popular programming language. It follows C and Java, which remained number one and number two on the list, respectively. C++, which had been third, is now fourth on the list.
Objective-C is used primarily for mobile development, specifically for developing iOS apps, while C++ is typically used in enterprise application development. Some observers say the news from Tiobe suggests that mobile development is growing in importance while enterprise development declines.