Obj-C - NSArray missing data when looping through?

Question

I'm trying to loop through my array (finalArray) using the below code:

AppDelegate.m

 NSUserDefaults *final = [NSUserDefaults standardUserDefaults];
         NSArray *finalArray = [final objectForKey:@"notifyTimes"];

      NSLog(@"Time from AppDelegate in Background %@", finalArray);
    
    for (int i = 0; i<finalArray.count; i++) {
        
        NSString *dateString = [finalArray objectAtIndex:i++];
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"MMM d yyyy h:mm a"];
    NSDate *dateFromString = [dateFormatter dateFromString:dateString];
    
    NSLog(@"Date according to app delegate frm string %@", dateFromString);

        UILocalNotification *notification = [[UILocalNotification alloc]init];
        notification.fireDate =  dateFromString;

        [notification setAlertBody:@"Reminder: You have an upcoming appointment!"];
   
        [[UIApplication sharedApplication] scheduleLocalNotification:notification];
    }

For some strange reason, when I log finalArray the first time (outside of my loop), the following data is returned, which is correct:

Time from AppDelegate in Background (
    "Apr 14 2021 12:04 PM",
    "Apr 17 2021 12:27 PM",
    "Apr 27 2021 12:28 PM",
    "Apr 14 2021 12:47 PM",
    "Apr 30 2021 1:45 PM",
    "Apr 27 2021 1:45 PM",
    "Apr 14 2021 12:03 PM",
    "Apr 30 2021 11:46 AM",
    "Apr 29 2021 11:20 AM",
    "Apr 14 2021 12:40 PM",
    "Apr 14 2021 12:56 PM",
    "Apr 14 2021 1:20 PM",
    "Apr 14 2021 1:08 PM",
    "Apr 14 2021 1:20 PM"
)

But when I loop through this same array and log the result, the loop is missing multiple dates from the above logged:

2021-04-14 13:21:04.485190-0700 [18644:1261621] Date according to app delegate frm string Wed Apr 14 12:04:00 2021
2021-04-14 13:21:04.493588-0700 [18644:1261621] Date according to app delegate frm string Tue Apr 27 12:28:00 2021
2021-04-14 13:21:04.494519-0700 [18644:1261621] Date according to app delegate frm string Fri Apr 30 13:45:00 2021
2021-04-14 13:21:04.495384-0700 [18644:1261621] Date according to app delegate frm string Wed Apr 14 12:03:00 2021
2021-04-14 13:21:04.496157-0700 [18644:1261621] Date according to app delegate frm string Thu Apr 29 11:20:00 2021
2021-04-14 13:21:04.496913-0700 [18644:1261621] Date according to app delegate frm string Wed Apr 14 12:56:00 2021
2021-04-14 13:21:04.497700-0700 [18644:1261621] Date according to app delegate frm string Wed Apr 14 13:08:00 2021

Any insight onto why this is happening?

jnpdx · Accepted Answer · 2021-04-14 20:32:11Z

1

You are incrementing i inside your loop on this line:

NSString *dateString = [finalArray objectAtIndex:i++];

You probably just want:

NSString *dateString = [finalArray objectAtIndex:i];

By incrementing inside the loop you were unintentionally skipping every other element.

answered Apr 14, 2021 at 20:32

jnpdx

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1 Comment

Brittany Over a year ago

Ahhh total oversight. THANK YOU. Haha that was driving me mental.

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