NSDate，NSCalendar

NSLog(@"%@",[NSDate date]);

打印结果：

2015-06-30 08:42:14 +0000

把它转换成2015年6月30日 8时42分14秒怎么转？

   *********************** 时间转字符串*************************
 1     NSDate *now = [NSDate date];
 2     NSDateFormatter *format = [[NSDateFormatter alloc]init];
 3     format.dateFormat = @"yyyy-MM-dd HH:mm:ss";
 4     NSString *nowString = [format stringFromDate:now];
 5     NSDate *newTime = [NSDate date];
 6     CGFloat delta = [newTime timeIntervalSinceDate:now];
 7     
 8     //NSLog(@"%@,%f",nowString,delta); 
       //打印结果：

2016-03-30 18:09:18,0.001518

 9     
10     ********************字符串转时间*******************************
11     NSString *str = @"2015-03-30 19:33:00";
12     NSDate *nowDate = [format dateFromString:str];
13     //NSLog(@"%@",nowDate);
14     
      **********************日历******************************************
15     NSCalendar *calendar = [NSCalendar currentCalendar];
16     //NSLog(@"%@",calendar);
17     NSCalendarUnit unit = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond;
18     NSDateComponents *components = [calendar components:unit fromDate:now toDate:nowDate options:0];
19     NSLog(@"%@,%zd,%zd,%zd",components,components.year,components.month,components.day);
20     打印结果：

<NSDateComponents: 0x7b791630>

Calendar Year: 0

Month: -11

Day: -30

Hour: -22

Minute: -36

Second: -18,0,-11,-30

**************************获取时间对应的年月等，分钟，秒什么的类似**********************************

21     NSInteger year = [calendar component:NSCalendarUnitYear fromDate:nowDate];
22     NSInteger month = [calendar component:NSCalendarUnitMonth fromDate:nowDate];
23     
24     NSLog(@"%zd,%zd",year,month);
打印结果：

2015,3

NSCalendar *calendar = [NSCalendar currentCalendar];
    NSString *oldTime = @"2014-12-31 23:59:59";
    NSString *newTime = @"2015-01-01 00:00:01";
    NSDateFormatter *format = [[NSDateFormatter alloc]init];
    format.dateFormat = @"yyyy-MM-dd HH:mm:ss";
    NSDate *oldDate = [format dateFromString:oldTime];
    NSDate *newDate = [format dateFromString:newTime];
   
    
    NSCalendarUnit unit = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond;
    NSDateComponents *comp = [calendar components:unit fromDate:oldDate toDate:newDate options:0];
    
    NSLog(@"%@",comp);

打印结果：

<NSDateComponents: 0x79e9d9c0>

Calendar Year: 0

Month: 0

Day: 0

Hour: 0

Minute: 0

Second: 2