iphone - iOS draw line with both arrow with start-end point while finger touch end and rotate from start or end point -

i need making drawing demo.

when user draws line using finger, line has directional arrows on both ends. when finger releases, draws line "?" (question-mark) in center of line.

then, when user taps on "?", show new view , user can enter value, , value in line.

and can add multiple lines on capture-image , can delete selected line.

i don't understand how can start developing these features please give me idea or link, or suggestion start develop feature.

you should use uitapgesturerecognizer , uibezierpath. have person taps @ 1 point , taps @ second point, make uibezierpath between 2 points. question mark in middle make line goes first point (half distance between point 1 , point 2 - 20pt). , same other half of line (so have space in middle of line.