I’m trying to check through thousands of lines in video subtitle files (in .srt format) and searched the internet for days on end for a solution, but to no avail. The subs contain in/out timestamps as shown in the following example:
61
00:08:35,504 --> 00:08:38,629
Do you know where he left the car keys?
in hours, minutes, seconds and milliseconds (notice the European-style comma before the millisecond part, representing the decimal point). What I plan to do is parse the timestamp into its two components and check the difference between them, since many are faulty. I built a simple test function to handle the plain hh:mm:ss part which works well:
-(IBAction)checkSubLength:(id)sender
{
NSString *inStr = #"10:10:45";
NSString *outStr = #"10:20:57";
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:#"hh:mm:ss"];
NSDate *inTime = [dateFormatter dateFromString:inStr];
NSDate *outTime = [dateFormatter dateFromString:outStr];
NSTimeInterval distanceBetweenDates = [outTime timeIntervalSinceDate:inTime];
NSLog(#"time difference:%.3f", distanceBetweenDates);
}
However, I just can’t get the fractional part to display no matter what I try. How can I modify/change my code do that? Any help much appreciated.
You need to specify the millis in the format string:
NSString *inStr = #"10:10:45,111";
NSString *outStr = #"10:20:57,222";
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:#"hh:mm:ss,SSS"];
NSDate *inTime = [dateFormatter dateFromString:inStr];
NSDate *outTime = [dateFormatter dateFromString:outStr];
NSTimeInterval distanceBetweenDates = [outTime timeIntervalSinceDate:inTime];
NSLog(#"time difference:%.3f", distanceBetweenDates);
which then prints
time difference:612.111
as expected
Related
My python backend uses the isoformat() method on UTC date times, which results in strings that look like 2014-01-14T18:07:09.037000. Following other examples, I'm trying to create NSDates from those strings (passed up in JSON packets):
NSDateFormatter *dateFormatter = [NSDateFormatter new];
[dateFormatter setDateFormat:#"yyyy-MM-dd'T'HH:mm:S"];
NSLog(#"cycle_base %#", myFields[#"cycle_base"]);
self.cycleBase = [dateFormatter dateFromString: myFields[#"cycle_base"]];
NSLog(#"cycleBase %#", self.cycleBase);
I've tried variants on the S part (which is supposed to be fractional seconds?) of the format string, but to no avail. I always get a nil back. What am I doing wrong?
iOS 7 follows the Unicode Technical Standard #35, which is a list of format patterns.
In this document you will find that the format string for fractional seconds is capitalized S.
NSString *string = #"2014-01-14T18:07:09.037000";
NSDateFormatter *formatter = [NSDateFormatter new];
formatter.dateFormat = #"yyyy-MM-dd'T'HH:mm:ss.S";
NSDate *date = [formatter dateFromString:string];
NSLog(#"%#", date);
This will net you a valid NSDate object. Don't forget to set the proper time zone and locale on your NSDateFormatter object.
Maybe somebody can help explain why I am getting a null value when converting a string to a date. It all looks right but I'm obviously missing something here.
Some background:
This iPad app will be used in different countries and I will need to do a calculation on the date to see if 90 days have passed since a user last logged in.
I have a SQLite Database with a DateLastIn field set as TEXT
My Object has a DateLastIn property set as NSDate
When populating my record object I set up a NSDateFormatter as such..
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"yyyy-MM-dd hh:mm:ss"]; // SQLite default date format
Then I read in the DateLastIn (Using FMDB wrapper for SQLite).
// test SQLite as String
NSString *testDate = [results stringForColumn:#"DateLastIn"];
NSLog(#"DateLastIn straight from DB (string) shows %#", testDate);
Result:
DateLastIn straight from DB (string) shows 2012-04-23 18:20:51
All is good so far. Next I test converting this to an NSDate object e.g
NSDate *aDate = [[NSDate alloc] init];
aDate = [formatter dateFromString:testDate];
NSLog(#"Using formmater on string date results in: %#", aDate);
Result:
Using formmater on string date results in: (null)
I have tried DATETIME in SQLite, I've tried using NSString in my object instead of NSDate and seem to be going around in circles.
Any help much appreciated.
NSDateFormatter uses the format patterns from the Unicode Technical Standard #35.
For the hour format, you need HH (Hour [0-23]) not hh (Hour [1-12]).
I changed your date format to HH not hh and it works. Here is my test code....
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"yyyy-MM-dd HH:mm:ss"]; // SQLite default date format
// test SQLite as String
NSString *testDate = #"2012-04-23 18:20:51";
NSDate *aDate = [formatter dateFromString:testDate];
NSLog(#"Using formmater on string date results in: %#", aDate);
I need to display the current Date and Time.
I have used ;
NSDate *currentDateNTime = [NSDate date];
I want to have the current date and time (Should display the system time and not GMT time).
The output should be in a NSDate format and not NSString.
for example;
NSDate *currentDateNTime = [NSDate date];
// Do the processing....
NSDate *nowDateAndTime = .....; // Output should be a NSDate and not a NSString
Since all NSDate is GMT referred, you probably want this:
(don'f forget that the nowDate won't be the actual current system date-time, but it's "shifted", so if you will generate NSString using NSDateFormatter, you will see a wrong date)
NSDate* currentDate = [NSDate date];
NSTimeZone* currentTimeZone = [NSTimeZone timeZoneWithAbbreviation:#"GMT"];
NSTimeZone* nowTimeZone = [NSTimeZone systemTimeZone];
NSInteger currentGMTOffset = [currentTimeZone secondsFromGMTForDate:currentDate];
NSInteger nowGMTOffset = [nowTimeZone secondsFromGMTForDate:currentDate];
NSTimeInterval interval = nowGMTOffset - currentGMTOffset;
NSDate* nowDate = [[NSDate alloc] initWithTimeInterval:interval sinceDate:currentDate];
Every moment in time is the same moment in time everywhere around the world —- it is just expressed as different clock times in different timezones. Therefore, you can't change the date to some other date that represents the time in your timezone; you must use an NSDateFormatter that you feed with the timezone you are in. The resulting string is the moment in time expressed in the clock time of your position.
Do all needed calculations in GMT, and just use a formatter for displaying.
Worth reading
Does [NSDate date] return the local date and time?
Some useful resources for anyone coming to this more recently:
Apple date and time programming guide do read it if you're doing anything serious with dates and times.
https://developer.apple.com/library/content/documentation/Cocoa/Conceptual/DatesAndTimes/DatesAndTimes.html#//apple_ref/doc/uid/10000039i?language=objc
Useful category on NSDate with lots of utilities does allow a ~new~ date to be generated based on an existing date.
https://github.com/erica/NSDate-Extensions
There's also a swift version of the category
https://github.com/erica/SwiftDates
You need an NSDateFormatter and call stringFromDate this method to get a string of your date.
NSDateFormatter *dateformater = [[NSDateFormatter alloc] init];
[dateformater setDateFormat:#"yyyyMMdd,HH:mm"];
NSString *str = [dateformater stringFromDate: currentDateNTime];
use this method
-(NSDate *)convertDateToDate:(NSDate *) date
{
NSDateFormatter *formatter = [[[NSDateFormatter alloc] init] autorelease];
NSDate *nowDate = [[[NSDate alloc] init] autorelease];
[formatter setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];
[formatter setDateFormat:#"yyyy-MM-d H:m:s"];
NSString * strdate = [formatter stringFromDate:date];
nowDate = [formatter dateFromString:strdate];
return nowDate;
}
this may return you what you want.
i hope you this may help you.
I have app that is a basic timer. It tracks the number of seconds the app has run. I want to convert it so the seconds (NSUInteger) are displayed like: 00:00:12 (hh:mm:ss). So I've read this post:
NSNumber of seconds to Hours, minutes, seconds
From which I wrote this code:
NSDate *date = [NSDate dateWithTimeIntervalSince1970:[[self meeting] elapsedSeconds]];
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"hh:mm:ss"];
It works fine, but it starts out with 04:00:00. I'm not sure why. I also tried doing something like:
NSDate *date = [NSDate dateWithTimeIntervalSinceNow:[[self meeting] elapsedSeconds] * -1];
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"hh:mm:ss"];
Thinking that it would display the counter correctly, but it does a wierd 01:23:00, then just flops to 04:00:00 and stays there for the rest of the time.
MS
This is similar to a previous answer about formatting time but doesn't require a date formatter because we aren't dealing with dates any more.
If you have the number of seconds stored as an integer, you can work out the individual time components yourself:
NSUInteger h = elapsedSeconds / 3600;
NSUInteger m = (elapsedSeconds / 60) % 60;
NSUInteger s = elapsedSeconds % 60;
NSString *formattedTime = [NSString stringWithFormat:#"%u:%02u:%02u", h, m, s];
While there are easier ways of doing this (#dreamlax has a very good way), let me explain what is wrong with your example and let's get it working:
First, the reason that it is showing 04:00:00 (well, it is probably actually showing 04:00:12) is because it is converting the time from UTC/GMT to your local time. To fix this, you need to add the following line:
[formatter setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];
Then, it will no longer show 04:00:12 because it doesn't convert the timezone. Unfortunately, it will now show 12:00:12 instead of 00:00:12 because it is midnight. In order to fix that, have it convert the string to 24 hour time instead by using the HH formatter instead of hh:
[formatter setDateFormat:#"HH:mm:ss"];
Keep in mind that since this was designed to work with times, that it will not work for more than 24 hours (because it will "roll over" to midnight again).
The full code would be:
NSDate *date = [NSDate dateWithTimeIntervalSince1970:[[self meeting] elapsedSeconds]];
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"HH:mm:ss"];
[formatter setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];
NSLog(#"%#", [formatter stringFromDate:date]);
// Results: 00:00:12
I have a countdown timer which countsdown from the current date/time to a specific future date/time. It is working great except for one problem. I input the future date using NSDateFormatter and dateFromString. It doesn't seem to be able to accept any time (hour) over 12 though indicating it is not support 24 hour clock. Is there a way to enable 24 hour clock support or a workaround? Here is some of my code:
NSDateFormatter *df = [[NSDateFormatter alloc] init];
[df setDateFormat:#"yyyy-MM-dd hh:mm:ss"];
NSDate *myDate = [df dateFromString:#"2010-03-14 15:00:00"];
NSDateFormatter follows the Unicode standard for date and time patterns. Use 'H' for the hour on a 24-hour clock:
NSDateFormatter *df = [[NSDateFormatter alloc] init];
[df setDateFormat:#"yyyy-MM-dd HH:mm:ss"];
NSDate *myDate = [df dateFromString:#"2010-03-14 15:00:00"];
I had the same problem and using HH worked only on some devices, like Roger also verified. In the end this was the solution that worked for me, I hope it works for others. Finding this answer was difficult, there are no forums with it, it was literally trial and error following the apple documentation.
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
NSLocale *enUSPOSIXLocale = [[NSLocale alloc] initWithLocaleIdentifier:#"en_US_POSIX"];
[dateFormatter setLocale:enUSPOSIXLocale];
NSString *dateFormat = #"dd/MM/yyyy HH:mm"; //MM for month, mm for minutes
[dateFormatter setDateFormat:dateFormat];
[dateFormatter setTimeZone:[NSTimeZone localTimeZone]];
date = [dateFormatter dateFromString:string];
My solution on Swift:
let formatter = NSDateFormatter()
var defIdentifer = formatter.locale.localeIdentifier
if !defIdentifer.hasSuffix("_POSIX") {
defIdentifer = defIdentifer+"_POSIX"
let locale = NSLocale(localeIdentifier: defIdentifer)
formatter.locale = locale
}
formatter.dateFormat = "HH:mm"
I had a similar problem recently, instead of HH, NSDateFormatter ignored hh, a(AM/PM Symbol) and G (cyclic era name) in my app.
And I was surprised to find that if I go to localization setting of my device and make some random choice, all the freaks are gone and the error cannot be produced again. Very weird.
Then I tested on simulator to do some study on it. There is my solution:
After you created the NSDateFormatter, explicitly set the locale property even you are using current locale, more importantly, DON'T use [NSLocale currentLocale], this one is bugged and can be somehow "overriden" by user setting, use systemLocale or explicitly create an NSLocale instance using a locale identifer.
Taken from the Apple Technical Q&A on NSDateFormatters
Q: I'm using NSDateFormatter to parse an Internet-style date, but this fails for some users in some regions. I've set a specific date format string; shouldn't that force NSDateFormatter to work independently of the user's region settings?
A: No. While setting a date format string will appear to work for most users, it's not the right solution to this problem. There are many places where format strings behave in unexpected ways.
This is how I have done mine in Swift:
private let dateFormatter: NSDateFormatter = {
let dateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"
dateFormatter.locale = NSLocale(localeIdentifier: "en_US_POSIX")
dateFormatter.timeZone = NSTimeZone.init(forSecondsFromGMT: 0)
return dateFormatter
}()
Objective C version of getting NSDate from 24-hour string when user has set 12 hour format on their iPhone without changing locale and setting timezone:
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
NSString *localeId = dateFormatter.locale.localeIdentifier;
if (! [localeId hasSuffix:#"_POSIX"]) {
localeId = [localeId stringByAppendingString:#"_POSIX"];
dateFormatter.locale = [NSLocale localeWithLocaleIdentifier:localeId];
}
dateFormatter.dateFormat = #"yyyy-MM-dd'T'HH.mm.ss";
NSDate *date = [dateFormatter dateFromString:dateText];