Coloured dots forming the top quarter of the Apple logo on the banner represents the iconic Bosphorus bridge's lights. The bridge connects Europe to Asia. Istanbul literally is a city located in both Europe and Asia. Here's a photo of the bridge.
Also Apple is said to open 4 more stores in Turkey by the end of 2015. One, located in the Asian side of Istanbul was photographed under construction, in a mall called "Akasya".
I'm pretty excited about this cause it means decent Apple customer service, Apple care, international guarantee and probably product launches simultaneously with the world. Up until now it has always been US, UK, Germany, France launch, then second tier country launch, then 3rd and then Turkey. If iPhones were launched early-Sep, it would officially arrive to Turkey mid-november. If this could move us up to at least 2nd tier it would be amazing.
[politics]
As a side note; I'm super annoyed and angry about the Turkish government's unacceptable demonisation of social media and I hope they'll get the answer on this Sunday's elections. Most of the people can still connect to Twitter and youtube just by changing their DNSs anyways but this attitude is non-democratic and unacceptable. In my eyes, the prime-minister is not legitimate anymore because he is literally above the law. [/politics]