iphone – 如何根据对象的属性比较两个NSSets？

概述我有两个nssets. nsset1: person.id = 1, person.id = 2, person.id = 3nsset2: person.id = 1, person.id = 2 结果应该是： nsset1 - nsset2: person (with id 3)nsset2 - nsset1: null 这两个集中具有相同id的对象是不同的对象,所以我不能简单地做minu 我有两个nssets.

nsset1: person.ID = 1,person.ID = 2,person.ID = 3nsset2: person.ID = 1,person.ID = 2

结果应该是：

nsset1 - nsset2: person (with ID 3)nsset2 - nsset1: null

这两个集中具有相同ID的对象是不同的对象,所以我不能简单地做minusSet.

我想做的事情如下：

nsset1: person.ID = 1,person.ID = 3nsset2: person.ID = 4,person.ID = 5

结果应该是这样的：

nsset1 - nsset2: person (ID 1),person (ID 2),person (ID 3)nsset2 - nsset1: person (ID 4),person (ID 5)

做这个的最好方式是什么？

解决方法 你应该尝试这样的事情

NSSet* nsset1 = [NSSet setWithObjects:person_with_ID_1,person_with_ID_2,person_with_ID_3,nil];NSSet* nsset2 = [NSSet setWithObjects:person_with_ID_2,person_with_ID_4,nil];// retrIEve the IDs of the objects in nsset2NSSet* nsset2_IDs = [nsset2 valueForKey:@"objectID"]; // only keep the objects of nsset1 whose 'ID' are not in nsset2_IDsNSSet* nsset1_minus_nsset2 = [nsset1 filteredSetUsingPredicate:    [nspredicate predicateWithFormat:@"NOT objectID IN %@",nsset2_IDs]];

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