Apple has sold over 3 billion iPhones since its first smartphone in 2007. Samsung got there first, but there are some caveats to consider.

Apple's best revenue growth in three years failed to impress, with shares down about 1% in volatile trading on Friday, as investors questioned whether a tariff-driven surge in iPhone sales would last.

According to Apple's recent earnings call, tariffs will add another $1.1 billion to its costs this quarter. What does that mean for you?