point 1
The main reason behind Apple's success is its software which is not hackable. However, nowadays Android is also having latest and high-end security on their operating system but still somehow Apple is ahead in security field.
point 2
Apple iPhone runs on iOS and the only one software is made for Apple iPhone that is also designed by Apple. So Apple can advantage this, in other hand the Google makes Android operating system for almost 90 percent smartphone that runs today.
point 3
So, every time Google releases Android operating version for the phone, these are for all smartphone which is not the good because all smartphone in the market are different and their task is different. So one software for all is not a kind of reliable which later can make complication to the phones.
Above mentioned are the simple reason behind apple's success and apple's reliability.
