IOS阶段学习第15天笔记(OC NSDate的操作)

 1 NSDate *newdate=[NSDate date];
 2 //时间格式化字符串
 3 NSDateFormatter *formatter = [[NSDateFormatter alloc]init];
 4 [formatter setDateFormat:@"yyyy-MM-dd HH:mm:ss MMM eee a"];
 5 NSString *strdate = [formatter stringFromDate:newdate];
 6 NSLog(@"%@",strdate);
 7 
 8 //时间字符串转换为时间类型
 9 NSDateFormatter * formatter2 = [[NSDateFormatter alloc]init];
10 NSString * nstr =@"2014年05月01日 10点23分18秒";
11 [formatter2 setDateFormat:@"yyyy年MM月dd日  hh点mm分ss秒"];
12 NSDate * date3 = [formatter2 dateFromString:nstr];
13 //解决时分秒转换不准确问题
14 NSTimeZone *fzone = [NSTimeZone systemTimeZone];
15 NSInteger finterval = [fzone secondsFromGMTForDate: date3];
16 NSDate *fDate = [date3  dateByAddingTimeInterval: finterval];
17 NSLog(@"%@",fDate);
18 
19 //获取系统时间的年月日时分秒部分
20 NSCalendar *cal = [NSCalendar currentCalendar];
21 //Mac 10.10以前的系统使用 NSYearCalendarUnit
22 unsigned int unitFlags = NSCalendarUnitYear |NSCalendarUnitMonth|NSCalendarUnitDay|NSCalendarUnitHour|NSCalendarUnitMinute|NSCalendarUnitSecond;
23 NSDateComponents *d = [cal components:unitFlags fromDate:newdate];
24 NSLog(@"年=%ld",[d year]);
25 NSLog(@"月=%ld",[d month]);
26 NSLog(@"日=%ld",[d day]);
27 NSLog(@"时=%ld",[d hour]);
28 NSLog(@"分=%ld",[d minute]);
29 NSLog(@"秒=%ld",[d second]);
30 
31 //将传入时间字符串转换成需要的时间格式
32 NSString *dateStr=@"2013-08-13 20:28:40";
34 NSDateFormatter *format=[[NSDateFormatter alloc] init];
35 [format setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
36 NSDate *fromdate=[format dateFromString:dateStr];
37 //解决时分秒转换不准确问题
38 NSTimeZone *fromzone = [NSTimeZone systemTimeZone];
39 NSInteger frominterval = [fromzone secondsFromGMTForDate: fromdate];
40 NSDate *fromDate = [fromdate  dateByAddingTimeInterval: frominterval];
41 NSLog(@"fromdate=%@",fromDate);