json - Checking for new data on server -


i have application downloads data via nsurlconnection in form of json object; displays data user. new data may created on server @ point, best way 'realise' , download data?

at moment planning on having application download data every 30-40 seconds, , check data downloaded against current data: if same nothing; if different, procede alterations. however, seems bit unnecessary, data may not change while. there more efficient way of updating application data when new server data created?

use etag if server supports it.

wikipedia etag
"if resource content @ url ever changes, new , different etag assigned."


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