How to Convert NSString into NSTimeInterval

Question

I have NSString that has value "22/04/2013 05:56", as per the requirement I just want to calculate this time and date and show some condition based messages.

First condition: If (String date = current date and stringtime = current time)||(string date = current date and string time < 1 minute from current time)

Second condition: If (String date = current date and stringtime > current time by how many minutes or hour)

Third Condition: To know is string date is yesterday.

Fourth Condition: To Know is string date is day before yesterday.

I am receiving this string from server. How can I achieve above things with this "22/04/2013 05:56" string.

Answer 1

You need to take 2 step:

1. convert string to NSDate
2. convert date to timeStamp

like below:

- (void) dateConverter{
    NSString *string = @"22/04/2013 05:56";
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    // this is imporant - we set our input date format to match our input string
    // if format doesn't match you'll get nil from your string, so be careful
    [dateFormatter setDateFormat:@"dd/MM/yyyy hh:mm"];
    NSDate *date = [[NSDate alloc] init];
    // voila!
    date = [dateFormatter dateFromString:string];
    NSLog(@"dateFromString = %@", date);

    //date to timestamp
    NSTimeInterval timeInterval = [date timeIntervalSince1970];
}

Then to achieve something like time ago following method will help, although it's not totally for you bu i believe you can modify it to help you!

- (NSString *) timeAgoFor : (NSDate *) date {
    double ti = [date timeIntervalSinceDate:[NSDate date]];
    ti = ti * -1;

    if (ti < 86400) {//86400 = seconds in one day
        return[NSString stringWithFormat:@"Today"];
    } else if (ti < 86400 * 2) {
        return[NSString stringWithFormat:@"Yesterday"];
    }else if (ti < 86400 * 7) {
        int diff = round(ti / 60 / 60 / 24);
        return[NSString stringWithFormat:@"%d days ago", diff];
    }else {
        int diff = round(ti / (86400 * 7));
        return[NSString stringWithFormat:@"%d wks ago", diff];
    }
}

Answer 2

From string using dateformatter convert it to date.Then you have to compare the dates and get the value

NSString *str=@"22/04/2013 05:56";
NSDateFormatter *dateFormatter=[[NSDateFormatter alloc]init];
[dateFormatter setDateFormat:@"dd/MM/YYYY hh:mm"];
NSDate *dateObj= [dateFormatter dateFromString:str];
NSLog(@"%@",dateObj);