ios - 使用 2 个排序描述符对数组进行排序

Question

我有一个 NSDictionary 对象数组，每个对象都有一个 EventDate 和 SecurityLevel。我想先按日期对它们进行排序，然后再按安全级别对它们进行排序。我该怎么做？

Obj1: SecurityLevel: 5, Date: 20/05/2015 22:03
Obj2: SecurityLevel: 5, Date: 05/03/2015 05:28
Obj3: SecurityLevel: 4, Date: 14/04/2015 11:01
Obj4: SecurityLevel: 4, Date: 07/08/2015 09:31
Obj6: SecurityLevel: 3, Date: 24/04/2015 21:06
Obj5: SecurityLevel: 3, Date: 29/01/2016 22:38
Obj7: SecurityLevel: 2, Date: 02/06/2015 20:49
Obj8: SecurityLevel: 2, Date: 13/07/2015 17:46
Obj9: SecurityLevel: 1, Date: 19/08/2015 07:57

它们应该这样排序:

Obj1: SecurityLevel: 5, Date: 20/05/2015 22:03
Obj2: SecurityLevel: 5, Date: 05/03/2015 05:28
Obj4: SecurityLevel: 4, Date: 07/08/2015 09:31
Obj3: SecurityLevel: 4, Date: 14/04/2015 11:01
Obj5: SecurityLevel: 3, Date: 29/01/2016 22:38
Obj6: SecurityLevel: 3, Date: 24/04/2015 21:06
Obj8: SecurityLevel: 2, Date: 13/07/2015 17:46
Obj7: SecurityLevel: 2, Date: 02/06/2015 20:49
Obj9: SecurityLevel: 1, Date: 19/08/2015 07:57

我做了类似的事情，但它没有按预期工作:

- (NSArray*)sortEventsByDateAndSecurity:(NSArray*)toSort
{
    NSSortDescriptor *securityDescriptor = [[NSSortDescriptor alloc] initWithKey:@"SeverityLevel" ascending:NO];
    NSArray *sortDescriptors = @[securityDescriptor];
    NSArray *sortedSecurity = [toSort sortedArrayUsingDescriptors:sortDescriptors];

    NSArray *reverseOrderUsingComparator = [sortedSecurity sortedArrayUsingComparator:^(id obj1, id obj2) {

        NSDictionary *dictObject1 = (NSDictionary*)obj1;
        NSDictionary *dictObject2 = (NSDictionary*)obj2;

        NSDate *obj1Date = [Utils stringToDate:[dictObject1 valueForKey:@"EventDate"] format:@"dd/MM/yyyy HH:mm"];
        NSDate *obj2Date = [Utils stringToDate:[dictObject2 valueForKey:@"EventDate"] format:@"dd/MM/yyyy HH:mm"];

        return [obj1Date compare:obj2Date];
    }];

    return reverseOrderUsingComparator;
}

Answer 1

您应该简单地调用 sortedArrayUsingDescriptors: 并使用 2 个而不是 1 个描述符的数组:

- (NSArray*)sortEventsByDateAndSecurity:(NSArray*)toSort
{
    NSSortDescriptor *securityDescriptor = [[NSSortDescriptor alloc] initWithKey:@"SeverityLevel" ascending:NO];
    NSSortDescriptor *eventDateDescriptor = [[NSSortDescriptor alloc] initWithKey:@"EventDate" ascending:NO comparator:^NSComparisonResult(NSString *obj1, NSString *obj2) {
        NSDate *obj1Date = [Utils stringToDate:obj1 format:@"dd/MM/yyyy HH:mm"];
        NSDate *obj2Date = [Utils stringToDate:obj2 format:@"dd/MM/yyyy HH:mm"];
        return [obj1Date compare:obj2Date];
    }];
    NSArray *sortDescriptors = @[securityDescriptor, eventDateDescriptor];
    return [toSort sortedArrayUsingDescriptors:sortDescriptors];
}

在这种情况下，第二个排序描述符将仅应用于在第一个排序描述符方面相等的对象。对于您的情况，这意味着具有相同 SecurityLevel 的对象将按 EventDate 排序。