iphone - 核心数据 TableView 部分使用 NSSortDescriptor 按工作日排序

Question

我目前正在尝试将对象数组按日顺序排序，以便可以按正确的顺序对它们进行分组，即周一、周二、周三，然后按开始时间进行分组。

唯一的问题是我不知道如何做到这一点，我的代码目前如下所示:先按字母顺序排序，然后按时间排序:

NSString *sectionKey = nil;
switch (tab) {

case kByWeekA: {
NSSortDescriptor *sortDescriptor1 = [[NSSortDescriptor alloc] initWithKey:@"day" ascending:NO];
NSSortDescriptor *sortDescriptor2 = [[NSSortDescriptor alloc] initWithKey:@"starttime" ascending:YES];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor1, sortDescriptor2, nil];
[fetchRequest setSortDescriptors:sortDescriptors];
[sortDescriptor1 release];
[sortDescriptor2 release];
[sortDescriptors release];
sectionKey = @"day";
break;
}
case kByWeekB:{
NSSortDescriptor *sortDescriptor1 = [[NSSortDescriptor alloc] initWithKey:@"day" ascending:YES];
NSSortDescriptor *sortDescriptor2 = [[NSSortDescriptor alloc] initWithKey:@"starttime" ascending:YES];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor1, sortDescriptor2, nil];
[fetchRequest setSortDescriptors:sortDescriptors];
[sortDescriptor1 release];
[sortDescriptor2 release];
[sortDescriptors release];
sectionKey = @"day";
break;
}
default:
break;
}

请帮忙!

Answer 1

我看到两种解决方案:

1. 为您的排序描述符创建一个自定义比较，该比较会查看“day”键并根据需要对它们进行排序。请参阅指定自定义比较 here .
2. 将“day”键设置为整数，并按所需顺序使用枚举作为日期值。

更新 2选项 2 的示例代码:

-将“day”属性更改为数字 (Int16) 并添加 transient (非持久)“dayName”字符串属性。

-添加工作日的枚举:

typdef enum {
    kMonday,
    kTuesday,
    kWednesday,
    kThursday,
    kFriday,
    kSaturday,
    kSunday
} WeekDay;

- 将托管对象的“day”属性设置为 NSNumber 对象。例如:

object.day = [NSNumber numberWithInteger:kMonday];

-实现 transient “dayName”属性的 getter 函数:

- (NSString*)dayName {
    switch ((WeekDay)self.day.integerValue) {
        case kMonday:
            return @"Monday";
            break;
        case kTuesday:
            return @"Tuesday";
            break;
        case kWednesday:
            return @"Wednesday";
            break;
        case kMonday:
            return @"Monday";
            break;
        case kThursday:
            return @"Thursday";
            break;
        case kFriday:
            return @"Friday";
            break;
        case kSaturday:
            return @"Saturday";
            break;
        case kSunday:
            return @"Sunday";
            break;
    }
}

-在获取请求中，按“day”排序并使用“dayName”作为部分名称键路径。

更新
注意:选项 1 对于对数组进行排序效果很好，但 Core Data 会针对“不支持的 NSSortDescriptor 选择器:weekdayCompare:”抛出“NSInvalidArgumentException”异常

选项 1 的示例代码:

// category on NSString for custom comparison
@interface NSString (WeekdayComparison)
- (NSComparisonResult)weekdayCompare:(NSString*)otherDay;
@end
@implementation NSString (WeekdayComparison)
- (NSComparisonResult)weekdayCompare:(NSString*)otherDay {
    NSArray *weekDays = [NSArray arrayWithObjects:@"Sunday", @"Monday", @"Tuesday", @"Wednesday", @"Thursday", @"Friday", @"Saturday", nil];

    NSUInteger selfIndex = [weekDays indexOfObject:self];
    NSUInteger otherDayIndex = [weekDays indexOfObject:otherDay];

    if (selfIndex < otherDayIndex) {
        return NSOrderedAscending;
    }
    else if (selfIndex > otherDayIndex) {
        return NSOrderedDescending;
    } else {
        return NSOrderedSame;
    }
}
@end

要使用新的比较方法:

NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"day" ascending:YES selector:@selector(weekdayCompare:)];
NSArray *sortDescriptors = [NSArray arrayWithObjects:sortDescriptor, nil];
[sortDescriptor release];