Objective-c NSDate 取时间，日期，星期等

NSDate

//得到当前的日期
 NSDate *date = [NSDate date];
 NSLog(@"date:%@",date);
 
 //得到(24 * 60 * 60)即24小时之前的日期，dateWithTimeIntervalSinceNow:
 NSDate *yesterday = [NSDate dateWithTimeIntervalSinceNow: -(24 * 60 * 60)];
 NSLog(@"yesterday:%@",yesterday);

NSDateFormatter *formatter =[[NSDateFormatter alloc] init];
 NSDate *date = [NSDate date];
 [formatter setTimeStyle:NSDateFormatterMediumStyle];
 

 NSCalendar *calendar = [[NSCalendaralloc] initWithCalendarIdentifier:NSGregorianCalendar];

    NSDateComponents *comps = [[NSDateComponentsalloc] init]  ;

    NSInteger unitFlags = NSYearCalendarUnit |

    NSMonthCalendarUnit |

    NSDayCalendarUnit |

    NSWeekdayCalendarUnit |

    NSHourCalendarUnit |

    NSMinuteCalendarUnit |

    NSSecondCalendarUnit;

    

    comps = [calendar components:unitFlags fromDate:date];

    

    int week = (int)[compsweekday];

    int year=(int)[compsyear];

    int month = (int)[compsmonth];

    int day = (int)[compsday];

 

    int hour = (int)[compshour];

    int min = (int)[compsminute];

    int sec = (int)[compssecond];

    NSLog(@"week%d",week);

    NSLog(@"year%d",year);

    NSLog(@"month%d",month);

    NSLog(@"day%d",day);

    NSLog(@"hour%d",hour);

    NSLog(@"min%d",min);

    NSLog(@"sec%d",sec);