【问题标题】:Array of dictionary filter using predicate - swift3使用谓词的字典过滤器数组 - swift3
【发布时间】:2018-08-13 23:08:47
【问题描述】:

我有很多字典。

>[{"name": "John",
"address": 
{"home": "addr1", 
"work": "add2"}
},
{"name": "Anu",
"address": {"home": "addr1", 
"work": "add2"}
}]

我正在像这样将它保存到用户默认值 -

让 personData1 = ["name": "John", "address": {"home": "addr1", "work": "add2"}] 作为 [String : Any] 让 personData2 = ["name": "Anu", "address": {"home": "addr1", "work": "add2"}] as [String : Any]

var persons = [personsData, personsData1]
UserDefaults.standard.set(forKey: "persons") 

用另一种方法检索它并根据名称过滤它们。 let name = "约翰"

遇到错误

无法使用“((Any?) -> Bool)”类型的参数列表调用“过滤器”

这里是代码:-

func test () {

    let personData1 = ["name": "John", "addresses": ["home":"addr1", "work": "addr2"]] as [String : Any]
    let personData2 = ["name": "And", "addresses":  ["home":"addr1", "work": "addr2"]] as [String : Any]

    let persons = [personData1, personData2]
    (UserDefaults.standard.set(persons, forKey: "persons")

    print("Saved ----\(UserDefaults.standard.value(forKey: "persons"))")

    if let savedPersons = UserDefaults.standard.value(forKey: "persons") {
        let namePredicate = NSPredicate(format: "name like %@", name);

        var filteredArray: [[String:Any]] = savedPersons.filter { namePredicate.evaluate(with: $0) }

        print("names = \(filteredArray)")
    }
}

如果我尝试像这样过滤 -

let filteredArray = savedBrs.filter { $0["name"] == name }

得到不同的错误 -

“任何”类型的值没有成员“过滤器”

【问题讨论】:

  • 请在问题中包含过滤数组的代码。

标签: ios swift3 closures


【解决方案1】:

NSPredicate

let arr = [["name":"Rego","address":["one":"peek","two":"geelo"]],["name":"pppp","address":["one":"peek","two":"geelo"]]]

let neededName = "Rego"

let pre = NSPredicate(format: "name == %@",neededName)

let result = arr.filter { pre.evaluate(with:$0) } 

print(result)

没有NSPredicate

let result = arr.filter { $0["name"] as? String  == neededName }

【讨论】:

  • 我这样声明字典 - 让 arr1: [[String:Any]] = [ ["name":"Rego","address":["one":"peek","two ":"geelo"]],["name":"pppp","address":["one":"peek","two":"geelo"]]] 我们不能使用 Any 吗?
  • 这个声明默认给出 [[String:Any]]
  • 如果我保存然后从用户默认值中检索此值,我会收到错误 -> 类型为“任何?”的值没有成员“过滤器”
  • 阅读时使用 UserDefaults.standard.array(forKey: "persons")
  • 知道了。谢谢!我像正常值一样检索它
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