ios 获取当前时间

1.第一种返回的时间是一个整个的字符串。

     NSDate *timeDate = [NSDate date];
     NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
     [dateFormatter setDateFormat:@"YYYY-MM-dd hh:mm:ss"];
     NSString *locationString = [dateFormatter stringFromDate:timeDate];
     return locationString;

2.第二种是分离出单个时间点，然后拼接字符串返回（星期也有，这里没有写）。

    NSDate *timeDate = [NSDate date];
    NSCalendar *cal = [NSCalendar currentCalendar];
    NSUInteger unitFlags = NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond;
    NSDateComponents *conponent = [cal components:unitFlags fromDate:timeDate];

    NSInteger year = [conponent year];
    NSInteger month = [conponent month];
    NSInteger day = [conponent day];
    NSInteger hour = [conponent hour];
    NSInteger min = [conponent minute];
    NSInteger sec = [conponent second];

    NSString *nsDateString= [NSString stringWithFormat:@"%4ld-%2ld-%2ld %2ld:%2ld:%2ld", year, month, day,hour, min, sec];
    return nsDateString;