由NSDate转换为NSString:
SDateFormatter*dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
NSString*strDate = [dateFormatter stringFromDate:[NSDate date]];
由NSString转换为NSDate:
NSDateFormatter*dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
NSDate *date =[dateFormatter dateFromString:@"2010-08-04 16:01:03"];
比较2个时间段的间隔
NSCalendar *cal = [NSCalendar currentCalendar];
unsigned int unitFlags = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond;
NSDateComponents *components = [cal components:unitFlags fromDate:[self.formatter dateFromString:sendString] toDate:[self.formatter dateFromString:endSreing] options:0];
日期之间比较可用以下方法
-(BOOL)isEqualToDate:(NSDate *)otherDate;
与otherDate比较，相同返回YES
- (NSDate*)earlierDate:(NSDate *)anotherDate;
与anotherDate比较，返回较早的那个日期
- (NSDate*)laterDate:(NSDate *)anotherDate;
与anotherDate比较，返回较晚的那个日期
-(NSComparisonResult)compare:(NSDate *)other;
该方法用于排序时调用:
.当实例保存的日期值与anotherDate相同时返回NSOrderedSame
.当实例保存的日期值晚于anotherDate时返回NSOrderedDescending
.当实例保存的日期值早于anotherDate时返回NSOrderedAscending
