从包含User类对象的NSMutableArray获取属性的唯一对象

Question

@interface User : NSManagedObject
@property (nonatomic, retain) NSString * user_name;
@property (nonatomic, retain) NSString * group_id;
@end

NSMutableArray包含User类型的对象集我希望基于属性检索唯一对象user_name 意味着我想防止重复user_name

---

NSMutableArray *arrayBikePartsFiltering = [NSMutableArray new];

arrayAsFoundSubPart = @[@{
                           partid:12,
                           name : @"Silencer"
                          },
                          @{
                           partid:11,
                           name : @"Gear"
                           },
                          @{
                               partid:13,
                               name : @"Break"
                           },
                          @{
                               partid:12,
                               name : @“Silencer”
                           },];

        for (BikeParts *subPart in arrayAsFoundSubPart) {
            
            BOOL isFound = NO;
            for (BikeParts *subPartl2 in array BikeParts Filtering) {
                if ([[subPartl2.part_id stringValue] isEqualToString:[subPart.part_id stringValue]]) {
                    isFound = YES;
                    break;
                }
            }
            if (!isFound) {
                [arrayBikePartsFiltering addObject:subPart];
            }
            
        }

按照上述阵列我想partid=12和name="silencer"只有一次导致阵列,我想:

arrayAsFoundSubPart = @[@{
                           partid:12,
                           name : @"Silencer"
                          },
                          @{
                           partid:11,
                           name : @"Gear"
                           },
                          @{
                               partid:13,
                               name : @"Break"
                           }
                          ];

Answer 1

NSSet 是您所需要的您可以使用 NSOrderedSet 来保留顺序：

NSOrderedSet* set = [[NSOrderedSet alloc] initWithArray:arrayAsFoundSubPart];

这将为您提供一组完全独特的对象；

如果您使用自定义类，您应该实现isEqual方法来比较对象（例如通过 Id）：

- (BOOL)isEqual:(BikeParts*)object {
  return ([object isKindOfClass:[BikeParts class]] && [object.name isEqual:self.name]);
}

结果集将包含唯一对象的有序序列。

或者，您可以循环遍历数组并按 id 将值分配给字典：

NSMutableDictionary* dict = [NSMutableDictionary new];
for (BikeParts *subPart in arrayAsFoundSubPart) {
  //if (!dict[subPart.name])
    dict[subPart.name] = subPart;
}

结果将在dict.allValues

编辑：按名称过滤而不是按 ID 过滤