Question

考虑具有以下属性的CustomObject类：

@property(nonatomic, strong) NSNumber *source;
@property(nonatomic, strong) NSArray<CustomObject2> *linkedItems;
@property(nonatomic, strong) NSString *parentId;

如何构建NSPredicate来处理以下场景：

所有CustomObject个source值为1且非空/非零linkedItems数组的对象。
所有CustomObject个source值为2且parentId等于item1的对象。
除CustomObjects或source

1

2

例如：

Custom Object 1
source = 1
linkedItems = Custom Object2 1, CustomObject2 2
parentId = nil

Custom Object 2
source = 1
linkedItems = nil
parentId = nil

Custom Object 3
source = 2
linkedItems = nil
parentId = item1

Custom Object 4
source = 2
linkedItems = nil
parentId = item2

Custom Object 5
source = 3
linkedItems = Custom Object2 3
parentId = nil

使用谓词后，我希望有对象1,2和5。

我为这个问题难以理解......有什么想法吗？

Answer 1

查找NSCompoundPredicate的文档，其中包含的类方法可以使用其他谓词作为输入构建AND，OR和NOT条件的谓词。

Answer 2

    //All CustomObject objects with source value of 1 and non-empty/non nil linkedItemsarray.
    let predicateA = NSPredicate(format: "(source == 1) AND (linkedItems != nil) AND (linkedItems.isEmpty == false)")


    //All CustomObject objects with source value of 2 and parentId equal to item1.
    let predicateB = NSPredicate(format: "(source == 2) AND (parentId != %@"), item1)


    //All other CustomObjects with source values other than 1 or 2
    let predicateC = NSPredicate(format: "(source != 1) AND (source != 2)")

    let predicate = NSCompoundPredicate(type: .AndPredicateType, subpredicates: [predicateA,predicateB,predicateC]) 

    let filtered = yourArray.filteredArrayUsingPredicate(predicate)

如何构建具有多种复杂条件的NSPredicate

2 个答案: