Ramper1 beat me to it
judging from the replies above it suggests it is, but many times i've heard that "phones with a flight safe mode myst have that enabled now" (for t/o etc.). this implies the apple flight mode is sufficient.
You've missed the end of the PA where they say "and then switched off" so in full what they're trying to say is turn flight mode on, turn the phone off, then if you turn the phone on in flight it should automatically be in flight mode, although this may not be true of all phones.
Where is this 10,000 feet thing coming from for when you can start using electronic devices? The PA says they must not be used during take off and landing, but can be used for the rest of the flight.
For me, the take off is complete by any definition when the captain releases the cabin crew, and they make all their announcements about the toilet, the smoke detector, and the in flight service, typically at about 1-2000'. At this point I always break out my tablet and start my in flight entertainment, several times in row 1 right in front of the cabin crew with no objections raised.
It is then polite to put all electronics away when the pilots call for the cabin to be secured at 10 mins to landing.
Is there a specific FAA thing about 10,000', or has it just been made up on here?