我有一个具有 2 个属性的实体,一个 NSDate 和一个 bool 值。 (这将是一个大“ table ”)
我需要计算两个日期之间 bool 值的所有"is"和“否”值,并按天分组。我怎样才能做到这一点?
The result I'm looking for is
{
totalYes = 10,
totalNo = 5,
date = dd-mm-yyyy
},
{
totalYes = 15,
totalNo = 3,
date = dd-mm-yyyy
},
等等
谢谢
最佳答案
您可以尝试这种方法:
1)获取所有带YES的实体,按日期排序
2)遍历这个数组并用带有日期值和是的数量的字典填充数组
3)然后,对 noe 做同样的事情,将 no 的数量添加到该字典数组中。
NSFetchRequest *request = [[NSFetchRequest alloc]init];
request.entity = [NSEntityDescription entityForName:@"Day" inManagedObjectContext:context];
request.predicate = [NSPredicate predicateWithFormat:@"yesorno = %@",YES];
NSError *error = nil;
request.sortDescriptors =[NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"date" ascending:YES]];
//Here you get all the enteties with YES,sorted by date
NSArray *days = [context executeFetchRequest:request error:&error];
NSMutableArray *arrayOfDates = [NSMutableArray array];
int firstDay = [[[NSCalendar currentCalendar]components:NSDayCalendarUnit fromDate:[[days objectAtIndex:0]date]]day];
//Add the first day dictionary
[arrayOfDates addObject:[NSMutableDictionary dictionaryWithObjectsAndKeys:[[days objectAtIndex:0]date],@"Day", nil];
int numberOfYes = 0;
int dayNumber = 0;
for(NSManagedObject *day in days)
{
if( [[[NSCalendar currentCalendar]components:NSDayCalendarUnit fromDate:[day date]]day]>firstDay)
{
//save number of yeses for the previous day,because we are done with it
[[arrayOfDates objectAtIndex:dayNumber]setValue:[NSNumber numberWithInt:numberOfYes] forKey:@"NumberOfYes"];
numberOfYes = 1;
dayNumber++;
firstDay = [[[NSCalendar currentCalendar]components:NSDayCalendarUnit fromDate:[day date]]day];//date with new day
[arrayOfDates addObject:[NSMutableDictionary dictionaryWithObjectsAndKeys:[day date],@"Day", nil];//Add this day dictionary to array
}else
{
numberOfYes++;
}
}
//And somrthing similar to No
关于objective-c - 核心数据、计数和分组依据,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/9777337/