iphone - 現在の日付を日付文字列と比較する

Question

現在の日付と比較したいデータベースに文字列の日付があります。たとえば6/13/2013 11:15:00 PM、データベースの日付です。今日の日付と比較したいと思います。どうすればこれを達成できますか？
ありがとう..

Answer 1

NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"MM/dd/YYYY hh:mm:ss a"];
NSDate *dbDate = [formatter dateFromString:@"your_date_string_from_db"];
if ([dbDate compare:[NSDate date]] == NSComparisonResult_value)
{
    //Do what you want accordingly
}

NSComparisonResult_value はこれらのいずれかです

enum {
   NSOrderedAscending = -1,
   NSOrderedSame,
   NSOrderedDescending
};

Answer 2

こいつを使ってみる

 NSDateFormatter *df = [[NSDateFormatter alloc] init];
    [df setDateFormat:@"MM/dd/yyyy"];
    NSDate *dt1 = [[NSDate alloc] init];
    NSDate *dt2 = [[NSDate alloc] init];
    dt1 = [df dateFromString:yourDatabaseDate];
    dt2 = [df dateFromString:[NSDate date]];
    NSComparisonResult result = [dt1 compare:dt2];
    switch (result)
    {
        case NSOrderedAscending: 
             NSLog(@"%@ is greater than %@", dt2, dt1); 
              break;
        case NSOrderedDescending:  
             NSLog(@"%@ is less %@", dt2, dt1);
             break;
        case NSOrderedSame:
             NSLog(@"%@ is equal to %@", dt2, dt1);
             break;
        default:
             NSLog(@"erorr dates %@, %@", dt2, dt1);
             break;
    }