Question

我在swift 4.0中工作，我在MutableArray中有模型对象， NSPredicate无法正常工作。

             //Here is code
            //Model class:
            class Modelclass: NSObject
            {
                var firstName:String!
                var lastName:String!
            }

            // Viewcontroller doing predicate:
            let ary = NSMutableArray()

            let userModel          = Modelclass()
            userModel.firstName    = "Arrya"
            userModel.lastName     = "stark"
            ary.add(userModel)

            let commitPredicate = NSPredicate(format: "firstName == %@", "Arrya")
            let resultAry       = ary.filtered(using: commitPredicate)
            print(resultAry)

Answer 1

我解决了这个问题，解决方案1：

    //I just added below code in model class

    extension Modelclass {
        @objc override func value(forKey key: String) -> Any? {
            switch key {
            case "firstName":
                return firstName
            case "lastName":
                return lastName
            default:
                return nil
            }
        } 
   }

解决方案2：

在变量之前添加@objc：

        class Modelclass: NSObject
        {
            @objc var firstName:String!
            @objc var lastName:String!

        }

Answer 2

var是针对Mutable Content / Variables
在swift中，您可以使用filter替代NSPredicate

尝试这样：

            //Model class:
            class Modelclass
            {
                var firstName: String
                var lastName: String

                init(firstName: String, lastName: String) {
                    self.firstName = firstName
                    self.lastName = lastName
                }
            }

            // Viewcontroller doing predicate:
            var ary:[Modelclass] = []

            let userModel = Modelclass(firstName: "Arrya", lastName: "stark")
            ary.append(userModel)

            let resultAry = ary.filter{ $0.firstName == "Arrya" }
            print(resultAry)

NSPredicate对象模型数组过滤器在Swift 4.0中无法正常运行

2 个答案: