objective-c - 带子数组的 NSPredicate

Question

我正在查看以下类型的数据结构:

{    author = "Author 1";    channelIds =         (        7    );},{    author = "Author 2";    channelIds =         (        7,        1    );},,{    author = "Author 3";    channelIds =         (        3,        7    );}

I'd like to build an array consisting of all items where channeldIds = 7.

I was trying things along the lines of the following predicate:

NSPredicate * filterById = [NSPredicate predicateWithFormat:@"channelIds[0] = '7'"];

• 我怎样才能在这里做我想做的事？
• 我可以有 x 个 channelId，有什么方法可以在谓词中迭代吗？

蒂亚，S.

Answer 1

更简单:

NSPredicate *filterById = [NSPredicate predicateWithFormat:@"channelIds CONTAINS %@", @"7"];

这是假设您的 channelIds 值是一个 strings 数组。如果它是一个数字数组 (NSNumber)，那么您的格式字符串将只是 @"channelIds CONTAINS 7"。