Question: I am working on Quiz App. In my app I want to get difference between quiz start time and end time. How to get difference between start and end time.

Thanks in advance.

Answer: 
You can use **NSDate** `- (NSTimeInterval)timeIntervalSinceDate:(NSDate *)anotherDate` for this purpose.
The `NSDate` class has a method `timeIntervalSinceDate` that does the trick.

```
NSTimeInterval interval = [firstDate timeIntervalSinceDate:secondDate];

```