ios - 在 Swift 中使用关键字过滤数组数组

Question

let searchResultItem1 = SearchResult()
searchResultItem1.type = "contact"
searchResultItem1.typeTitle = "CONTACTS"
searchResultItem1.results = ["Joe" , "Smith" , "Alan" , "Nick" , "Jason"]

let searchResultItem2 = SearchResult()
searchResultItem2.type = "address"
searchResultItem2.typeTitle = "ADDRESS"
searchResultItem2.results = ["829 6th Street North Fullerton" , "669   Windsor Drive Randallstown" , "423 Front Street Lacey"]
searchResults.append(searchResultItem1)
searchResults.append(searchResultItem2)

当我搜索“al”时，我希望返回一个结果为“[Alan]”的 SearchResult 和一个结果为“["669 Windsor Drive Randallstown"]”的 SearchResult

我试过下面的过滤器，但返回空数组。

let results = searchResults.filter({$0.results.contains("al")})

Answer 1

正如其他两个答案所指出的，您正在结果数组中搜索值为“al”的项目。您想要的实际上是返回一组结果，缩小到仅匹配的结果:

struct SearchResult {
    let type:String
    let typeTitle:String
    let results:[String]
}

let searchResultItem1 = SearchResult(
    type: "contact",
    typeTitle: "CONTACTS",
    results: ["Joe" , "Smith" , "Alan" , "Nick" , "Jason"]
)

let searchResultItem2 = SearchResult(
    type:"address",
    typeTitle: "ADDRESS",
    results:["829 6th Street North Fullerton" , "669   Windsor Drive Randallstown" , "423 Front Street Lacey"]
)

var searchResults = [ searchResultItem1, searchResultItem2 ]

现在，再次为了方便起见，为 String 定义一个不区分大小写的 contains 函数:

extension String {
    func containsIgnoreCase(substring:String) -> Bool {
        return rangeOfString(
            substring,
            options: .CaseInsensitiveSearch,
            range: startIndex..<endIndex,
            locale: nil)?.startIndex != nil
    }
}

注意 String 已经有一个 contains 函数，它只是区分大小写，但如果这就足够了，你甚至不需要定义自己的。

现在，您可以使用 map 删除不包含您的搜索字符串的结果:

searchResults = searchResults.map({
    return SearchResult(
        type: $0.type,
        typeTitle: $0.typeTitle,
        results: $0.results.filter({
            $0.containsIgnoreCase("al")
        })
    )
})

而且，据推测，您还想消除任何没有实际结果的 SearchResult，因此请使用过滤器:

searchResults = searchResults.filter { $0.results.count > 0 }

当然，整个事情可以串成一个表达式:

searchResults = searchResults.map({
    return SearchResult(
        type: $0.type,
        typeTitle: $0.typeTitle,
        results: $0.results.filter({
            $0.contains("al")
        })
    )
}).filter { $0.results.count > 0 }

并且，您可以使用 flatMap 进一步减少一些迭代，它类似于 map，但消除了任何 nil 值:

searchResults = searchResults.flatMap {
    let results = $0.results.filter { $0.containsIgnoreCase("al") }
    if results.count > 0 {
        return SearchResult(type: $0.type, typeTitle: $0.typeTitle, results: results)
    } else {
        return nil
    }
}