NSMutableArray *sectionTitles;
[sectionTitles addObject:due];
How do I just add unique values to an array?
如何只为数组添加唯一值？
3 个解决方案
#1
28
See Rudolph's Answer
见鲁道夫的答案
My old answer below is now outdated and has been for awhile. Rudoph's reference to NSOrderedSet / NSMutableOrderedSet is the correct one since these classes were added after this Q and my A.
我下面的旧答案现在已经过时了，已经有一段时间了。 Rudoph对NSOrderedSet / NSMutableOrderedSet的引用是正确的，因为在这个Q和我的A.之后添加了这些类。
Old Answer
老答案
As Richard said, NSMutableSet works well but only if you don't need to maintain an ordered collection. If you do need an ordered collection a simple content check is the best you can do:
正如Richard所说，NSMutableSet运行良好，但前提是您不需要维护有序集合。如果您确实需要有序的收藏，您可以做的最好的简单内容检查：
if (![myMutableArray containsObject:newObject])
[myMutableArray addObject:newObject];
Update based on comment
根据评论更新
You can wrap this in a method like -addUniqueObject: and put it in an NSMutableArray category.
您可以将它包装在类似-addUniqueObject的方法中：并将其放在NSMutableArray类别中。
#2
19
More 2012-ish answer (in case someone stumbled upon this in the future):
更多2012-ish的答案（万一有人在将来偶然发现）：
Use NSOrderedSet and NSMutableOrderedSet.
使用NSOrderedSet和NSMutableOrderedSet。
A note about performance right from NSOrderedSet docs:
有关NSOrderedSet文档的性能的说明：
You can use ordered sets as an alternative to arrays when the order of elements is important and performance in testing whether an object is contained in the set is a consideration— testing for membership of an array is slower than testing for membership of a set.
当元素的顺序很重要时，您可以使用有序集作为数组的替代，并且在测试集合中是否包含对象时的性能是一个考虑因素 - 对数组成员资格的测试比测试集合的成员资格要慢。
#3
5
Use NSMutableSet, it is best for these situations
使用NSMutableSet，最适合这些情况
iOS参考
Mac OSX参考
#1
28
See Rudolph's Answer
见鲁道夫的答案
My old answer below is now outdated and has been for awhile. Rudoph's reference to NSOrderedSet / NSMutableOrderedSet is the correct one since these classes were added after this Q and my A.
我下面的旧答案现在已经过时了，已经有一段时间了。 Rudoph对NSOrderedSet / NSMutableOrderedSet的引用是正确的，因为在这个Q和我的A.之后添加了这些类。
Old Answer
老答案
As Richard said, NSMutableSet works well but only if you don't need to maintain an ordered collection. If you do need an ordered collection a simple content check is the best you can do:
正如Richard所说，NSMutableSet运行良好，但前提是您不需要维护有序集合。如果您确实需要有序的收藏，您可以做的最好的简单内容检查：
if (![myMutableArray containsObject:newObject])
[myMutableArray addObject:newObject];
Update based on comment
根据评论更新
You can wrap this in a method like -addUniqueObject: and put it in an NSMutableArray category.
您可以将它包装在类似-addUniqueObject的方法中：并将其放在NSMutableArray类别中。
#2
19
More 2012-ish answer (in case someone stumbled upon this in the future):
更多2012-ish的答案（万一有人在将来偶然发现）：
Use NSOrderedSet and NSMutableOrderedSet.
使用NSOrderedSet和NSMutableOrderedSet。
A note about performance right from NSOrderedSet docs:
有关NSOrderedSet文档的性能的说明：
You can use ordered sets as an alternative to arrays when the order of elements is important and performance in testing whether an object is contained in the set is a consideration— testing for membership of an array is slower than testing for membership of a set.
当元素的顺序很重要时，您可以使用有序集作为数组的替代，并且在测试集合中是否包含对象时的性能是一个考虑因素 - 对数组成员资格的测试比测试集合的成员资格要慢。
#3
5
Use NSMutableSet, it is best for these situations
使用NSMutableSet，最适合这些情况
iOS参考
Mac OSX参考