How to check the time and date online?

hi i am making an app in which user sends xml to server and get response....

now i have to save the date and time of sending and response of that request....for this should i use iphone's date or check it online?

because my thin开发者_如何学Pythonking is that the iphone's date and time may not be correct.....always...so it is better to check the time online ....

i know the local part but need help regarding online check....please help

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Just use the local time. It will save you a lot of trouble and work. Or is your app so absolutely dependent on the correct time, like to display the current position of the sun or something ? If not, the local time is likely "good enough".

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If you need the same time as the server, then it would seem that you need to establish the offset between server time and local time, and then you can adjust your local timestamp.

Is there a way to get the (current) time from the server?

Assuming the timestamp you're saving is for the request sent from the iphone and the response received by the iphone, then it would actually seem logical to use local (iphone) time.

You could always use NTP (http://en.wikipedia.org/wiki/Network_Time_Protocol) to get the current time, but that doesn't guarantee the time is thesame as the server.

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You usually don't need absolute time of some sort, just the same time source as your server and your server's database.

So compare your local time with whatever the server thinks the time is and adjust accordingly.