如何根据世界，大陆，州，城市，地区，10英里和50英里的距离查找信息

i am new developer on iphone i need your help to do my application.i display all received messages on tableview and place a slider on right side in that slider i write some names (world,continent,state,city,region,10miles and 50miles)when selecting any value on the slider (state is selece state wise messages will display) programaticaly how it is possible.i am new developer on iphone i need your help t