问题描述
我想在swift 3中创建一个复杂的 NSCompoundPredicate ，但是，我不知道该怎么做。
I want to create a complicated NSCompoundPredicate in swift 3, however, I don't know how to do this.
假设我有5个谓词（p1，p2，p3，p4，p5）。我想实现以下条件：
Suppose I have 5 predicates (p1,p2,p3,p4,p5). I want to implement below conditions:
compound1 = (p1 AND p2 AND p3) // NSCompoundPredicate(type: .and,
//subpredicates: predicates)
compound2 = (p4 AND p5) // NSCompoundPredicate(type: .and,
//subpredicates: predicates)
compound3 = (compound1 OR compound2) // problem is here
fetchRequest.predicate = compound3
NSCompoundPredicate ，因为它是第二个参数，它获取了不需要的NSPredicates数组。最好的解决方案是什么？
NSCompoundPredicate as it's second argument gets array of NSPredicates that it doesn't desire. What is the best solution?
推荐答案
NSCompoundPredicate 继承自 NSPredicate ，因此您
可以将在第一步中创建的复合谓词
作为子谓词传递给另一个复合谓词：
NSCompoundPredicate inherits from NSPredicate, therefore youcan pass the compound predicates creates in the first stepsas subpredicate to another compound predicate:
let compound1 = NSCompoundPredicate(type: .and, subpredicates: [p1, p2, p3])
let compound2 = NSCompoundPredicate(type: .and, subpredicates: [p4, p5])
let compound3 = NSCompoundPredicate(type: .or, subpredicates: [compound1, compound2])
fetchRequest.predicate = compound3
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