ios - Comparing Two NSDates with specific constraints -

i working accomplish within 3 statements, check compares 2 times (stored nsdates) , executes code based on difference between 2 respectively. checks wishing implement ( < 3min ), ( > 3min < 3hrs ), , ( > 3hrs ). below recent attempt. suggestions appreciated, thank you!

nsdateformatter* df = [[nsdateformatter alloc] init]; [df setlocale:[[nslocale alloc] initwithlocaleidentifier:@"en_us"]]; [df settimezone:[nstimezone systemtimezone]]; [df setdateformat:@""]; [df setdateformat:@"hh:mm mm-dd-yyyy"];  nsdate* newdate = [df datefromstring:[df stringfromdate:[[_radios objectatindex:indexpath.row] attributeforkey:@"date_time_edt"]]];  nstimeinterval interval = [newdate timeintervalsincenow];  if(interval < 3 * 60) {     img.image = [uiimage imagenamed:@"tire_green.png"];     nslog(@"%@", newdate);     nslog(@"%f", interval); } else if(interval > 3 * 60  && interval < 3 * 60 * 60) {     img.image = [uiimage imagenamed:@"tire_yellow.png"];     nslog(@"%@", newdate); } else {     img.image = [uiimage imagenamed:@"tire_red.png"];     nslog(@"%@", newdate); } 

updated based on far long comment thread.

it turns out [[_radios objectatindex:indexpath.row] attributeforkey:@"date_time_edt"] returning nsnumber representing number of milliseconds since january 1st, 1970. there no need date formatters. can date value follows (which needs seconds, not milliseconds):

nsnumber *timestamp = [[_radios objectatindex:indexpath.row] attributeforkey:@"date_time_edt"]; nsdate *newdate = [nsdate datewithtimeintervalsince1970:[timestamp doublevalue] / 1000]; 

now can time interval since "now". keep in mind resulting interval negative if newdate in past (which true in case).

nstimeinterval interval = [newdate timeintervalsincenow]; 

since know interval negative since newdate in past, checks easier if make positive.

interval = -interval; // positive 

now can needed checks desired image.

if (interval < 3 * 60) { // < 3 minutes     img.image = [uiimage imagenamed:@"tire_green.png"]; } else if (interval > 3 * 60 * 60) { // > 3 hours     img.image = [uiimage imagenamed:@"tire_red.png"]; } else { // >= 3 minutes && <= 3 hours     img.image = [uiimage imagenamed:@"tire_yellow.png"]; }