NSTimeInterval in seconds between dates = nan

Question

NSTimeInterval executionTime = [self.EndDownloadTime timeIntervalSinceDate:self.StartDownloadTime];
NSLog(@"Execution Time: %f", executionTime);

Result is always "nan". When i switch EndDownloadTime and StartDownloadTime, time is "0.00000"

StartDownloadTime and EndDownloadTime are types of NSDate.

How do i get the seconds between the two dates?

Thank you in advance.

What you are doing looks correct to me. Log the start and end time values and add them to your question. — trojanfoe, Jun 07 '14 at 14:17
When you are debugging a problem and everything looks correct but the code is failing then an assumption must be wrong. There are two assumptions here (at least): the values of self.EndDownloadTime and self.StartDownloadTime. NSLog them or use the debugger examining the values as you step through. Note: In Cocoa* properties and variables and method names by convention begin with a lower case letter, case names with an uppercase letter. — zaph, Jun 07 '14 at 14:38

score 0 · Answer 1 · answered Jun 07 '14 at 14:25

Your code looks right. Try this and print value of variables to know if the two dates are correct.

NSTimeInterval executionTime = [self.EndDownloadTime timeIntervalSince1970] - [self.StartDownloadTime timeIntervalSince1970];
NSLog(@"Execution Time: %f", executionTime);

score 0 · Accepted Answer · edited Jun 07 '14 at 14:59

0

The simplest solution is a better method, check the docs when things seem complicated:

NSTimeInterval executionTime = [self.EndDownloadTime timeIntervalSinceDate:self.StartDownloadTime];

When you are debugging a problem and everything looks correct but the code is failing then an assumption must be wrong. There are two assumptions here (at least): the values of self.EndDownloadTime and self.StartDownloadTime. NSLog them or use the debugger examining the values as you step through.

Check everything:

NSLog(@"StartDownloadTime: %@", self.StartDownloadTime);
NSLog(@"StartloadTimeInterval: %f", [self.StartDownloadTime timeIntervalSince1970]);
NSLog(@"EndDownloadTime: %@", self.EndDownloadTime);
NSLog(@"EndDownloadTimeInterval: %f", [self.EndDownloadTime timeIntervalSince1970]);

NSTimeInterval executionTime = [self.EndDownloadTime timeIntervalSince1970] - [self.StartDownloadTime timeIntervalSince1970];
NSLog(@"Execution Time: %f", executionTime);

Note: In Cocoa* properties and variables and method names by convention begin with a lower case letter, class names with an uppercase letter. This makes it easier for others to understand your code.

edited Jun 07 '14 at 14:59

Zev Eisenberg

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answered Jun 07 '14 at 14:47

zaph

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`StartDownloadTime: (null) StartloadTimeInterval: 0.000000 EndDownloadTime: (null) EndDownloadTimeInterval: 0.000000 Execution Time: 0.000000` The problem is the "null", correct? But when i set the date to a label, it works correctly – Velocity Jun 07 '14 at 14:55
Now i know the problem, but i don't know how to solve it. In a first method, startDownloadTime is called an it returns the right value. But when a call startDownloadTime in another method, it returns (null). But i didn't change the variable.. :/ – Velocity Jun 07 '14 at 15:08
Please do two things: 1. Create a new question with the new problem. 2. Accept answers that provided the answer or are most helpful. This will increase your reputation and capabilities on SO. – zaph Jun 07 '14 at 15:17
1

@Velocity - before creating a new question, try to figure it out. Search code for touches to the two NSDates, implement a custom setter - (void)setStartDownloadTime:(NSDate *)date and add a breakpoint, etc. It seems this was a premature question, please don't create another. – danh Jun 07 '14 at 15:19

NSTimeInterval in seconds between dates = nan

2 Answers2