如果语句比较两个日期

Question

Im trying to update a plist file automaticlly if the file is over 24 hours old, but i cant figure out how to compare the two dates.

// get last modification date
NSString *dir = path;
NSDictionary *attributes = [[NSFileManager defaultManager] attributesOfItemAtPath:dir error:nil];
NSDate *date = [attributes fileModificationDate];

NSDate *fileModPlus24Hours = [NSDate dateWithTimeInterval:(24*60*60) sinceDate:date];

Thinking about something like:

if (date > fileModPlus24Hours) {
    // update file
}

Any suggestions?

Answer 1

if ([date compare:fileModPlus24Hours] == NSOrderedDescending) {
    // update file
}

The result of compare can be NSOrderedAscending , NSOrderedDescending or NSOrderedSame .

And I don't think your code will work either by comparing date to fileModPlus24Hours . You should be comparing the current date to fileModPlus24Hours instead:

NSDate *now = [NSDate date];
if ([now compare:fileModPlus24Hours] == NSOrderedDescending) {
    // update file
}