Swift map和filter函数原型基础示例
<div id="navCategory"><h5 class="catalogue">目录</h5><ul class="first_class_ul"><li>map函数原型</li><li>filter函数原型</li></ul></div><p class="maodian"></p><h2>map函数原型</h2><div class="jb51code"><pre class="brush:cpp;">/// Returns an array containing the results of mapping the given closure
/// over the sequence's elements.
///
/// In this example, `map` is used first to convert the names in the array
/// to lowercase strings and then to count their characters.
///
/// let cast = ["Vivien", "Marlon", "Kim", "Karl"]
/// let lowercaseNames = cast.map { $0.lowercased() }
/// // 'lowercaseNames' == ["vivien", "marlon", "kim", "karl"]
/// let letterCounts = cast.map { $0.count }
/// // 'letterCounts' ==
///
/// - Parameter transform: A mapping closure. `transform` accepts an
/// element of this sequence as its parameter and returns a transformed
/// value of the same or of a different type.
/// - Returns: An array containing the transformed elements of this
/// sequence.
@inlinable public func map<T>(_ transform: (Element) throws -> T) rethrows -> </pre></div>
<div class="jb51code"><pre class="brush:cpp;">let cast = ["Vivien", "Marlon", "Kim", "Karl"]
let lowercaseNames = cast.map {
$0.lowercased()
}
print(lowercaseNames) // ["vivien", "marlon", "kim", "karl"]
let arrayString = ["Ann", "Bob", "Tom", "Lily", "HanMeiMei", "Jerry"]
// 计算每个元素的个数，生成个数数组
let arrayCount = arrayString.map { (str) -> Int in
return str.count
}
print("arrayCount: \(arrayCount)")
// arrayCount: </pre></div>
<p class="maodian"></p><h2>filter函数原型</h2>
<div class="jb51code"><pre class="brush:cpp;">// @inlinable public func filter(_ isIncluded: (Element) throws -> Bool) rethrows ->
let array = [-5, 4, -3, 1, 2]
var resultArray = array.filter { (item) -> Bool in
return item > 0
}
print(resultArray) //
// 语法糖写法
resultArray = array.filter {
$0 > 0
}
print(resultArray) // </pre></div>
<p>以上就是Swift map和filter函数原型基础示例的详细内容，更多关于Swift map filter函数原型的资料请关注琼殿技术社区其它相关文章！</p>
<div class="art_xg">
<b>您可能感兴趣的文章:</b><ul><li>Swift 进阶 —— map 和 flatMap的使用</li><li>Swift函数提前返回实例详解</li><li>Swift如何调用Objective-C的可变参数函数详解</li><li>swift 常用高阶函数分享</li><li>C语言中调用Swift函数实例详解</li><li>深入理解swift变量和函数</li><li>详解Swift中的函数及函数闭包使用</li></ul>
</div>
</div>
<!--endmain-->
頁:
[1]