iOS获取系统时间

NSString* date;
NSDateFormatter* formatter = [[NSDateFormatteralloc]init];
       [formattersetDateFormat:@"YYYY-MM-dd%20hh:mm:ss"];
       date = [formatterstringFromDate:[NSDatedate]];

date 显示为 2011-11-01%2012:12:12

想实现查找几天前的时间，可以用这个方法
  NSDate* date = [[NSDate alloc] init];
        date = [date dateByAddingTimeInterval:-5*3600*24];
这是用现在的时间，往前面减5天，得到的时间。

 

好简单！简单的很假！

 

 

获取连续日期：

 NSDate *date = [NSDate date];
    // 2013-04-07 11:14:45
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    // HH是24进制，hh是12进制
    formatter.dateFormat = @"MM.dd";
    
    NSDateFormatter *formatter2 = [[NSDateFormatter alloc] init];
    // HH是24进制，hh是12进制
    formatter2.dateFormat = @"YYYY-MM-dd";
    
    // formatter.locale = [[[NSLocale alloc] initWithLocaleIdentifier:@"zh_CN"] autorelease];
    NSString *string = [formatter stringFromDate:date];
    NSLog(@"%@", string);
    // 返回的格林治时间
    NSMutableArray *dates = [NSMutableArray array];
//    NSMutableArray *weekDays = [NSMutableArray array];
    NSString * registe = @"3";
    if([registe integerValue]>1)
    {
        for (int i=0; i<[registe integerValue]; i++ ) {
            NSDate *newDate = [[NSDate alloc] initWithTimeIntervalSinceReferenceDate:([date timeIntervalSinceReferenceDate] - 24*3600*i)];
            
            NSString *currentDateStr = [formatter stringFromDate:newDate];
            [dates addObject:currentDateStr];
               NSLog(@"——————%@",dates);
            
               }
        for (int i= [registe intValue]; i<7; i++) {
            
             NSDate *newDate = [[NSDate alloc] initWithTimeIntervalSinceReferenceDate:( [date timeIntervalSinceReferenceDate] +24*3600 *(i- ([registe intValue]-1))*24*3600)];
//            NSDate *newDate = [[NSDate alloc] initWithTimeIntervalSinceReferenceDate:( [date timeIntervalSinceReferenceDate] +24*3600 *(i-1))];
            
            NSString *currentDateStr = [formatter stringFromDate:newDate];
            [dates addObject:currentDateStr];
            
            NSLog(@"哈哈哈哈%@",dates);
        }
       
        
    }