iOS下时间基础处理(NSDate NSDateFormatter等)

首先说一下iOS下时间处理相关的类。

NSDate 负责管理具体的时间的累

NSDateFormatter 负责设置时间显示格式，和NSDate配合使用。年月日设置如：yyyy-MM-dd

NSDateComponents 比较函数，和NSDate NSCalendar配合使用

NSCalendar 负责日历相关的功能

NSTimeZone
时区设置相关

示例1：

NSDate* now = [NSDate date];

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

NSDateComponents *comps = [[NSDateComponents alloc] init];

NSInteger unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSWeekdayCalendarUnit |

NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit;

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

int hour = [comps hour];

int min = [comps minute];

int sec = [comps second];

int year = [comps year];

int month = [comps month];

int day = [comps day];

timeLabel.text = [NSString stringWithFormat:@"%02d:%02d:%02d", hour, min,sec];

dateLabel.text = [NSString stringWithFormat:@"%04d-%02d-%02d", year, month, day];