Checking if one NSDate is greater than another

if (datStartDate > datEndDate) {

This doesn't seem t开发者_运维百科o work. I know there's a isEqual, etc., but how do I perform "is greater than"?

There are both NSDate.

The easiest method i'm aware is:

if( [firstDate timeIntervalSinceDate:secondDate] > 0 ) {

The other answers cover compare:, wanted to add some flavour ;).

To compare dates use -compare: method:

Return Value If:

• The receiver and anotherDate are exactly equal to each other, NSOrderedSame
• The receiver is later in time than anotherDate, NSOrderedDescending
• The receiver is earlier in time than anotherDate, NSOrderedAscending.

What about...

if ([datStartDate earlierDate: datEndDate] == datStartDate) {
    // datStartDate is earlier
} else {
    // datEndDate is earlier
}

As you have NSDates:

NSDate *datStartDate = [NSDate dateWithString:@"2010-10-01 03:00:00 +0900"];
NSDate *datEndDate   = [NSDate dateWithString:@"2010-10-01 04:00:00 +0900"];

if ( ([datStartDate compare:datEndDate]) == NSOrderedDescending ) {
    ...
}

Swift 2 version of accepted answer:

if firstDate.timeIntervalSinceDate(secondDate) > 0 {
    // firstDate is greater (further in the future) than secondDate
}

I've been working with NSDate and NSComparison result stuff for years and I can never for the life of me remember how this works. So I wrote a convenience extension on Date for it:

func isBefore(_ otherDate: Date) -> Bool {
    let result = self.compare(otherDate)
    switch result {
    case .orderedAscending:
        return true
    case .orderedSame,
         .orderedDescending:
        return false
    }
}

If you want to have an isAfter extension it just has to return true for orderedDescending.

if ([startDate compare:endDate] == NSOrderedAscending) {
        NSLog(@"startDate is EARLIER than endDate");
}