NSDate関連のメモ

NSDate

    NSDate *now = [NSDate date];

    // ロケールを指定する.
    NSLocale *locale = [NSLocale currentLocale];
    NSLog(@"now[%@]", [now descriptionWithLocale:locale]);

    // NSDateFormatterオブジェクトの生成.
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    [formatter setLocale:[NSLocale systemLocale]];
    [formatter setTimeZone:[NSTimeZone systemTimeZone]];

    // 日付から文字列への変換.
    [formatter setDateFormat:@"yyyy年MM月dd日 HH時mm分ss秒"];
    NSString *strDate = [formatter stringFromDate:now];
    NSLog(@"now2[%@]", strDate);

    // 文字列から日付への変換.
    [formatter setDateFormat:@"yyyy/MM/dd HH:mm:ss"];
    NSDate *oneDay = [formatter dateFromString:@"2013/12/12 23:59:59"];
    NSLog(@"now3[%@", [oneDay descriptionWithLocale:locale]);

    // 東京五輪までの日数.
    NSDate *tokyoOlympic = [formatter dateFromString:@"2020/07/24 20:00:00"];
    NSTimeInterval secs = [tokyoOlympic timeIntervalSinceDate:now];
    NSInteger dayes = round(secs/(60*60*24));
    NSLog(@"あと%d日", dayes);

    // 数値を指定してNSDateを取得する.
    NSDateComponents *components = [[NSDateComponents alloc] init];
    components.year = 2014;
    components.month = 1;
    components.day = 28;
    components.hour = 23;
    NSCalendar *cal = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
    date = [cal dateFromComponents:components];
    NSLog(@"date: %@", date);
    NSLog(@"date: %@", [date descriptionWithLocale:[NSLocale currentLocale]]);

    // NSDateから数値を取得する.
    components = [cal components:(NSDayCalendarUnit|NSHourCalendarUnit|NSSecondCalendarUnit) fromDate:date];
    NSInteger day = components.day;
    NSInteger hour = components.hour;
    NSInteger sec = components.second;
    NSLog(@"day=%ld hour=%ld sec=%ld", day, hour, sec);