Swift 如何基于排除数组不区分大小写过滤目标字符串数组

你之前的写法var filter = array2.filter({exclude.contains($0)})没有达到预期，是因为这个逻辑是判断array2的元素是否和exclude数组中的某一项完全相等，既没有做子串匹配，也没有处理大小写不敏感的需求。

正确的实现方式如下： #

基础实现（满足常规需求） #

使用Swift内置的range(of:options:)方法，传入.caseInsensitive参数实现大小写不敏感的子串匹配：

let exclude = ["text 1", "text 2", "APP", "John"]
let array2 = ["this is text 1", "This is text 2", "This App is under development", "John is working on this project", "This is great"]

let filteredResult = array2.filter { element in
    // 仅保留不包含任意排除项子串的元素
    !exclude.contains { excludeItem in
        element.range(of: excludeItem, options: .caseInsensitive) != nil
    }
}

// 输出：["This is great"]
print(filteredResult)

优化实现（大数据量下效率更高） #

如果exclude数组元素较多，可以提前把所有排除项转为小写，再统一判断，减少重复计算：

let exclude = ["text 1", "text 2", "APP", "John"]
let array2 = ["this is text 1", "This is text 2", "This App is under development", "John is working on this project", "This is great"]

// 提前把排除项全部转为小写，只计算一次
let lowercasedExcludes = exclude.map { $0.lowercased() }
let filteredResult = array2.filter { element in
    let lowerElement = element.lowercased()
    return !lowercasedExcludes.contains { lowerElement.contains($0) }
}

内容的提问来源于stack exchange，提问作者snksnk