用于多个字典键的Swift过滤器

Question

我正在为我的应用创建一个搜索栏.我正在使用该filter方法来获得结果.我想搜索多个键.

字典数组:

var people = [
               ["First": "John", "Last": "Doe"],
               ["First": "Steve", "Last": "Jobs"],
               ["First": "Elon", "Last": "Musk"]
             ]

我只能使用以下代码搜索"First"或"Last",但不能同时搜索两者:

searchResults = people.filter{
            var string = $0["Last"] 
            // or "First"

            string = string?.lowercaseString

            return string!.rangeOfString(searchText.lowercaseString) != nil
        }

Answer 1

一种方法是简单地将两个字段与搜索字符串进行比较:

var people = [
    ["First": "JohnMusk", "Last": "Doe"],
    ["First": "Steve", "Last": "Jobs"],
    ["First": "Elon", "Last": "Musk"]
]

var searchText = "Musk"

var searchResults = people.filter{
        var firstName = $0["First"]!.lowercaseString
        var lastName = $0["Last"]!.lowercaseString

       return firstName.rangeOfString(searchText.lowercaseString) != nil
              || lastName.rangeOfString(searchText.lowercaseString) != nil

}

这给了我这个结果:

2015-11-18 18:19:47.691 MyPlayground[36558:7031733] (
        {
        First = JohnMusk;
        Last = Doe;
    },
        {
        First = Elon;
        Last = Musk;
    }
)

我认为这就是你想要的.

Answer 2

这是另一种使用方法NSPredicate.NSPredicate有一个非常强大的语法,可以为你做一些非常好的事情.

let firstNameQuery = "jo"
let lastNameQuery = "mus"
// [cd] means case/diacritic insensitive. %K is used to pass in key names since FIRST and LAST are reserved keywords in NSPredicate
let predicate = NSPredicate(format: "%K CONTAINS[cd] %@ OR %K CONTAINS[cd] %@", "First", firstNameQuery, "Last", lastNameQuery)
let sorted = people.filter({
    return predicate.evaluateWithObject($0)
})
// sorted would contain John Doe and Elon Musk entries

在我的示例中,我传递了不同的搜索查询,以查找名字和姓氏,但您显然可以为两者传递相同的查询.只是展示了这种方法的力量.