But it is proving to be surprisingly porous. Cambridge Scientist Demonstrates $100 Hack of iPhone 6 | Digital Trends
For 100 bucks, and a bunch of time, you can crack a 4-digit pin in about 40 hours. A 6-digit pin takes longer. Into the 100s of hours.
And to think the FBI paid more than $1million. (Your tax dollars well spent!)
Systems and programs that are not subject to outside review can hardly be declared secure. Other systems have problems – but we know about them and they get fixed. Apple has had outstanding problems for years that no one – aside from some of the bad guys – have known about.
The moral of the story is probably that your smart phone – from whatever vendor – is not so smart, and should not hold all of you financial data.