string to date

gistfile1.m

    NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
    [dateFormat setDateFormat:@"yyyy-MM"];
    NSDate *date = [dateFormat dateFromString:@"2012-4"];

//1、字符串转换为日期

　　NSDateFormatter* dateFormat = [[NSDateFormatter alloc] init];//实例化一个NSDateFormatter对象
[dateFormat setDateFormat:@"yyyy-MM-dd HH:mm:ss"];//设定时间格式,这里可以设置成自己需要的格式
NSDate *date =[dateFormat dateFromString:@"1980-01-01 00:00:01"];

//2、日期转换为字符串
NSDateFormatter* dateFormat = [[NSDateFormatter alloc] init];//实例化一个NSDateFormatter对象
[dateFormat setDateFormat:@"yyyy-MM-dd HH:mm:ss"];//设定时间格式,这里可以设置成自己需要的格式
NSString *currentDateStr = [dateFormatter stringFromDate:[NSDate date]];

//3、字符串转int
Convert NSString to int
NSString *aNumberString = @"123";
int i = [aNumberString intValue];

//4、int转字符串
Convert int to NSString
int aNumber = 123;
NSString *aString = [NSString stringWithFormat:@"%d", aNumber];

/*

官方文档上对NSDateFormatter的格式串好像没详讲, 或许有,我没找到, 每次使用都是用谷歌摸索.

有幸找到一份比较全的文档, 翻译过来共享:

a:	AM/PM (上午/下午)

A:	0~86399999 (一天的第A微秒)

c/cc:	1~7 (一周的第一天, 周天为1)

ccc:	Sun/Mon/Tue/Wed/Thu/Fri/Sat (星期几简写)

cccc:	Sunday/Monday/Tuesday/Wednesday/Thursday/Friday/Saturday (星期几全拼)

d:	1~31 (月份的第几天, 带0)

D:	1~366 (年份的第几天,带0)

e:	1~7 (一周的第几天, 带0)

E~EEE:	Sun/Mon/Tue/Wed/Thu/Fri/Sat (星期几简写)

EEEE:	Sunday/Monday/Tuesday/Wednesday/Thursday/Friday/Saturday (星期几全拼)

F:	1~5 (每月的第几周, 一周的第一天为周一)

g:	Julian Day Number (number of days since 4713 BC January 1) 未知

G~GGG:	BC/AD (Era Designator Abbreviated) 未知

GGGG:	Before Christ/Anno Domini 未知

h:	1~12 (0 padded Hour (12hr)) 带0的时, 12小时制

H:	0~23 (0 padded Hour (24hr))  带0的时, 24小时制

k:	1~24 (0 padded Hour (24hr) 带0的时, 24小时制

K:	0~11 (0 padded Hour (12hr)) 带0的时, 12小时制

L/LL:	1~12 (0 padded Month)  第几月

LLL:	Jan/Feb/Mar/Apr/May/Jun/Jul/Aug/Sep/Oct/Nov/Dec 月份简写

LLLL: January/February/March/April/May/June/July/August/September/October/November/December 月份全称

m:	0~59 (0 padded Minute) 分钟

M/MM:	1~12 (0 padded Month) 第几月

MMM:	Jan/Feb/Mar/Apr/May/Jun/Jul/Aug/Sep/Oct/Nov/Dec

MMMM: January/February/March/April/May/June/July/August/September/October/November/December

q/qq:	1~4 (0 padded Quarter) 第几季度

qqq:	Q1/Q2/Q3/Q4 季度简写

qqqq:	1st quarter/2nd quarter/3rd quarter/4th quarter 季度全拼

Q/QQ:	1~4 (0 padded Quarter) 同小写

QQQ:	Q1/Q2/Q3/Q4 同小写

QQQQ:	1st quarter/2nd quarter/3rd quarter/4th quarter 同小写

s:	0~59 (0 padded Second) 秒数

S:	(rounded Sub-Second) 未知

u:	(0 padded Year) 未知

v~vvv:	(General GMT Timezone Abbreviation) 常规GMT时区的编写

vvvv:	(General GMT Timezone Name) 常规GMT时区的名称

w:	1~53 (0 padded Week of Year, 1st day of week = Sunday, NB: 1st week of year starts from the last Sunday of last year) 一年的第几周, 一周的开始为周日,第一周从去年的最后一个周日起算

W:	1~5 (0 padded Week of Month, 1st day of week = Sunday) 一个月的第几周

y/yyyy:	(Full Year) 完整的年份

yy/yyy:	(2 Digits Year)  2个数字的年份

Y/YYYY:	(Full Year, starting from the Sunday of the 1st week of year) 这个年份未知干嘛用的

YY/YYY:	(2 Digits Year, starting from the Sunday of the 1st week of year) 这个年份未知干嘛用的

z~zzz:	(Specific GMT Timezone Abbreviation) 指定GMT时区的编写

zzzz:	(Specific GMT Timezone Name) Z:	+0000 (RFC 822 Timezone) 指定GMT时区的名称


*/