iOS中对时间的处理（二）——获取时间及星期

一. NSString与NSDate之间转化

NSString转化为NSDate

[code][dateformatter setDateFormat:@"yyyy-MM-dd HH:mm"];
NSDate *date = [NSDate date];
NSString *dateStr = [dateformatter stringFromDate:date];

NSDate转化为NSString

[code][dateformatter setDateFormat:@"yyyy-MM-dd HH:mm"];
NSString = @"2015-07-11 10:00";
NSDate *date = [dateformatter dateFromString:date];

二. 获取当前日期及以后几天日期并加入数组

[code]    NSDateFormatter* formatter = [[NSDateFormatter alloc]init];
    [formatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
    NSDate *now = [NSDate date];
    NSMutableArray *dayArray = [NSMutableArray array];
    for (int i = 0; i <= 365; i ++) {
        NSDate *date = [now dateByAddingTimeInterval:i*3600*24];
        NSString *dateStr = [formatter stringFromDate:date];
        [dayArray addObject:dateStr];
    }

注意：转换格式只能用@”yyyy-MM-dd HH:mm:ss”，如果把yyyy写成YYYY，那么就会出现本年度12月份最后几天变成明年的现象，如下图，YYYY是取那一周所在的年份的日期。



三. 获取星期几

//注意：week为1时，是星期日

[code]-(void)week
{
    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:[NSDate date]];
        NSInteger week = [comps weekday];
        NSString *weekStr = [self getweek:week];
        NSLog(@"%@",weekStr);
}
-(NSString*)getweek:(NSInteger)week
{
    NSString*weekStr=nil;
    if(week==1)
    {
        weekStr=@"星期日";
    }else if(week==2){
        weekStr=@"星期一";
    }else if(week==3){
        weekStr=@"星期二";
    }else if(week==4){
        weekStr=@"星期三";
    }else if(week==5){
        weekStr=@"星期四";
    }else if(week==6){
        weekStr=@"星期五";
    }else if(week==7){
        weekStr=@"星期六";
    }
    return weekStr;
}