How to print Time stamps through out the program in iOS - iphone

Some of the operations in my app are taking a lot of time to execute. SO, i am planing to print time stamps from starting of the app execution to end in order to check the time taken for certain operations. Is there any way in order to do that so that i can keep track of all the time stamps in a continuos way...

You can just NSLog(#"Any sensible log message describing your location in the code") - the output in XCode contains the time it was logged, to the millisecond.

You can define a var at the start of the methods you want to analyse:
NSTimeInterval start = [NSDate timeIntervalSinceReferenceDate];
and then print it at the end:
NSLog(#"It took %f seconds in method <methodname>",[NSDate timeIntervalSinceReferenceDate] - start);
good luck!

Related

how can I store different times from stopwatch

I am confused regarding to calculation of two different times. In my game, when game starts then timer gets started (like stop watch) and it stops when game gets finished. Now I have to store best low time among previous time list.
I am getting time in hh:mm:ss format. how can I store this time so that i can compare it with different time in list ? I tried to store this value in NSString, but the comparison fails.
EDITED :
Let me clarify the Question :
For example how can I store different times from stopwatch and how to sort it in ascending order ?
any suggestions?
Thanks...
Take two NSDates, one at the game start and one at game finish, then calculate the difference.
NSDate *startDate = [NSDate date]; // At game start
NSTimeInterval interval = [[NSDate date] timeIntervalSinceDate:startDate]; // At game finish
NSlog(#"interval: %.2f", interval);
You could use
long stamp = (long)[[NSDate date] timeIntervalSince1970];
for each of your time-relevant situation since the posted code is giving you a UNIX-timestamp. This timestamp can be used in arithmetic operations/comparisons which should be exact what you are looking for.

UIDatePicker, time, and 1970

I've come across a small issue that I've been chewing on for a day or two now.
Using the Apple example project called DateCell I lifted its UIDatePicker and set it to time. I used this particular code as it did the animated slide on/off the screen.
My workflow is to set four values, start time, lunch time out, lunch time in, and stop time. I set these values by using [NSDate date].
I then use NSCalander:component calls to do some math such as "add 30 minutes to start time to get lunch time out," and "start time - lunch time out - 8 hours to get stop time."
The initial setup goes just fine. Clicking on the start time cell brings up the picker, and selecting a time change the other three times following my simple math formula's.
If the second row is selected, the lunch time out, the wheel comes up again to pick your lunch time out time. However this is where my problems start. It seems that my UIDatePickerModeTime wheel returns a date portion for January 1, 1970. And its this date portion that messes up my math formulas.
My question is, what can I do to fix this?
I've tried setting an initial, minimum time, in the XIB for the picker. This sort of works but when you pick a time on the wheel, the wheel spins itself to the time set in the XIB. This method doesn't have a clean feel to it.
I've tried settings the initWithTimeInterval class methods, but these block out times and isn't what I'm looking for I think.
I've also tried the NSDateFormatter:stringFromDate|dateFromString calls, and these had no affect.
What I have not done yet:
Custom defined date/time string.
Rebuilding UIDatePicker:Time from scratch
Am I over looking anything?
Thanks.
I've solved my problem, and here is how I addressed it.
Before I get to my answer I'm still really new to Objective-C and object oriented programming so my vocabulary doesn't know how to describe some of the things I've tried explaining. So take this into account when reading this.
Using UIDatePicker in time mode, i.e. you go into your NIB/XIB file and set your UIDatePicker object to 'time', will only return time. This is where I went wrong.
Using the NSDateComponent or any of the NSCalendar methods will bring out the date component of the picker. Thus you'll see January 1st, 1970 in the NSLog returns for example.
I had to find a new way of doing my math and manipulation of the times I was getting from the picker.
What I ended up using is NSTimeInterval, dateByAddingTimeInterval, and timeIntervalSinceDate. Research showed that NSTimeInterval is also a float type, so I used float to do some math as well.
Here an example -
if (indexPath.row == [labelArray indexOfObjectIdenticalTo:#"Clock Out"])
{
NSTimeInterval diffClockInOutToLunch = [outToLunch timeIntervalSinceDate:clockIn];
float remainingInTheDay = 28800 - diffClockInOutToLunch;
self.clockOut = [inFromLunch dateByAddingTimeInterval:remainingInTheDay];
cell.detailTextLabel.text = [self.dateFormatter stringFromDate:clockOut];
self.clockOutIndex = indexPath;
return cell;
}
I'm using a TableView to display my fields. When this 'if' statement is tripped it will populate the detailTextLabel of the line displaying "Clock Out." Visually the phrase "Clock Out" will be on the left side of the row, the time will be on the right side.
diffClockInOutToLunch is defined as a NSTimeInterval type. The operation being performed is timeIntervalSinceDate which essentially subtracts the value of outToLunch from the value of clockIn. Imagine outToLunch as being 11:00pm and clockIn as being 6:00am. This difference is 5 hours. NSTimeInterval stores values as seconds only so this difference of 5 hours is 18000 seconds.
I then perform a normal math operation using float. In this case I want to find out how many hours remain in the work day. This assumes the hours worked in a day is 8 hours. Because NSTimeInterval returns seconds, I converted 8 hours into seconds (28,800 seconds) and then subtract diffClockInOutToLunch from 28800. Now remainingInTheDay is equal to to 10800, or 3 hours.
The next operation I perform is set clockOut to the time our work day is finished. To do this I use the dateByAddingTimeInterval operation, which also is a NSDate method, so whatever it returns will be in a date/time format. In this operation we add remainingInTheDay (10,800 seconds) to inFromLunch (11:30am for example). Our clockOut time is now 2:30pm which is then sent through my DateFormatter and returned as a string to the cell of the TableView and also stored for later use.
Here's another example, from further down in my code -
- (void)clockInChanged
{
// Set clockIn value
self.clockIn = self.pickerView.date;
// Change the outToLunch time
self.outToLunch = [self.pickerView.date dateByAddingTimeInterval:5*60*60];
UITableViewCell *outToLunchCell = [self.tableView cellForRowAtIndexPath:outToLunchIndex];
outToLunchCell.detailTextLabel.text = [self.dateFormatter stringFromDate:outToLunch];
// Change the inFromLunch time
self.inFromLunch = [outToLunch dateByAddingTimeInterval:30*60];
UITableViewCell *inFromLunchCell = [self.tableView cellForRowAtIndexPath:inFromLunchIndex];
inFromLunchCell.detailTextLabel.text = [self.dateFormatter stringFromDate:inFromLunch];
// Change the clockOut time
NSTimeInterval diffClockInOutToLunch = [outToLunch timeIntervalSinceDate:clockIn];
float remainingInTheDay = 28800 - diffClockInOutToLunch;
self.clockOut = [inFromLunch dateByAddingTimeInterval:remainingInTheDay];
UITableViewCell *clockOutCell = [self.tableView cellForRowAtIndexPath:clockOutIndex];
clockOutCell.detailTextLabel.text = [self.dateFormatter stringFromDate:clockOut];
}
In this example, we've previously determined that the row pertaining to "Clock In" time was selected ("Touch Up Inside" if you will) and we drop to this method.
What happens in this method is whenever clockIn is changed using the picker, the times displayed in outToLunch, inFromLunch, and clockOut automatically update and are displayed.
This example shows that we capture the value on the picker (self.pickerView.date) as clockIn. We then use clockIn to seed our mess of dateByAddingTimeInterval's and so forth.
So. This is how I managed my times using UIDatePicker (which is set to time mode).
The short answer would be I was using the wrong methods to work with what my picker was turning.
I hope this helps you and hopefully it'll be here if I need it again too ;)

How can I create a count up timer with the format seconds:milliseconds?

I'm diving into iOS development and I'm trying to create a count up timer in one of my views. I have the NSTimer code figured out to call a selector once every 0.04 seconds that updates the UILabel. Where I'm having trouble is with the formatting of the current time (starting initially at 00:00). I figured the best way to do this was using the NSDate class, and related classes (NSDateFormatter, NSDateComponents, etc.), but the manipulating of the dates and formats is really confusing me and the code is getting unwieldy quickly. I was hoping there are some SO users that are comfortable using the NSDate class that could help me figure out a simple way to calculate the current time for a count up timer and convert it to an NString with the format 'seconds:milliseconds'.
I'd be happy to post my initial attempt at the NSDate code if requested, but I won't initially because it's really of no use and embarrassing :)
If you just want to display time elapsed since you started your timer you can store starting date somewhere (say, startDate variable) and calculate time interval using current date. Something like the following should work:
NSTimeInterval passed = [[NSDate date] timeIntervalSinceDate: startDate];
double intPart;
double fract = modf(passed, &intPart);
label.text = [NSString stringWithFormat:#"%d:%.2f", (int)intPart, fract];

Is there an objective-c/iPhone version of currentTimeMillis() from Java?

I need to time some events in the app I'm working on. In Java i used to be able to call currentTimeMillis() but there doesnt seem to be a version in Objective-c. Is there a way to check there current time without creating a NSDate and then parsing this object everytime i need this information?
Thanks
-Code
[[NSDate date] timeIntervalSince1970] * 1000 returns a the same value as currentTimeMillis()
CFAbsoluteTimeGetCurrent() and [NSDate timeIntervalSinceReferenceDate] both return a double starting at Jan 1 2001 00:00:00 GMT.
There's also CFAbsoluteTimeGetCurrent(), which will give you the time in double-precision seconds.
To get very cheap very precise time, you can use gettimeofday(), which is a C Function of the BSD kernel. Please read the man page for full details, but here's an simple example:
struct timeval t;
gettimeofday(&t, NULL);
long msec = t.tv_sec * 1000 + t.tv_usec / 1000;
Instead gettimeofday() you could also use [NSDate timeIntervalSinceReferenceDate] (the class method) and do your calculations with that. But they have the same problem: they operate on "wall clock time". That means your measurement can be off if leap seconds are added while your test is running or at the transition between daylight saving time.
You can use the Mach system call mach_absolute_time() on OS X and iOS. With the information returned by mach_timebase_info() this can be converted to nanoseconds.
The correct answer is [[NSDate date] timeIntervalSince1970]; this will give you current timestamp in milliseconds.
The answer given by #Noah Witherspoon returns current date but the year is not the current matching year.

Objective C: Compare timeInMillis with current time

In my iPhone application, I need to calculate the time difference between the time a message was created on the server, and the time my phone received it.
The server (Java) puts in a number returned by System.currentTimeMillis() as metadata along with the message.
How do I compare this number with the current time on the device? Could not find a suitable NSDate method to do this comparison.
Thanks in advance!
You might take a look at this SO answer and the -timeIntervalSinceDate: method.
You can use (NUInteger) ([[NSDate date] timeIntervalSince1970] * 1000)