In macOS 10.9+ & iOS 8+, there's a method on NSCalendar/Calendar that does exactly this!
- (BOOL)isDateInToday:(NSDate *)date
So you'd simply do
Objective-C:
BOOL today = [[NSCalendar currentCalendar] isDateInToday:date];
Swift 3:
let today = Calendar.current.isDateInToday(date)
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