Swift3.0 split函数切割字符串

阳光穿透心脏的1/2处 2022-09-29 14:57 310阅读 0赞

**我们先看函数的原型：**

public func split(separator: Self.Iterator.Element, maxSplits: Int = default, omittingEmptySubsequences: Bool = default) -> [Self.SubSequence]

**第一个参数就不用解释了，传入要切割的字符串，像这样**

let line = "BLANCHE:   I don't want realism. I want magic!"
    print(line.characters.split(separator: " ")
                         .map(String.init))
    // Prints "["BLANCHE:", "I", "don\'t", "want", "realism.", "I", "want", "magic!"]"

**下面看第二个参数，像这样，意思是切割几次，设置为1的话就把原来的字符串切成两个。**

// The second example passes `1` for the `maxSplits` parameter, so the
    // original string is split just once, into two new strings.
    
    print(line.characters.split(separator: " ", maxSplits: 1)
                         .map(String.init))
    // Prints "["BLANCHE:", "  I don\'t want realism. I want magic!"]"

第三个参数就很明确了，是否保留隐藏字符

// The final example passes `false` for the `omittingEmptySubsequences`
    // parameter, so the returned array contains empty strings where spaces
    // were repeated.
    
    print(line.characters.split(separator: " ", omittingEmptySubsequences: false)
                          .map(String.init))
    // Prints "["BLANCHE:", "", "", "I", "don\'t", "want", "realism.", "I", "want", "magic!"]"

看看官方文档对这三个参数的解释，懒得翻译了，也不是很难懂。

/// - Parameters:
    ///   - separator: The element that should be split upon.
    ///   - maxSplits: The maximum number of times to split the collection, or
    ///     one less than the number of subsequences to return. If
    ///     `maxSplits + 1` subsequences are returned, the last one is a suffix
    ///     of the original collection containing the remaining elements.
    ///     `maxSplits` must be greater than or equal to zero. The default value
    ///     is `Int.max`.
    ///   - omittingEmptySubsequences: If `false`, an empty subsequence is
    ///     returned in the result for each consecutive pair of `separator`
    ///     elements in the collection and for each instance of `separator` at
    ///     the start or end of the collection. If `true`, only nonempty
    ///     subsequences are returned. The default value is `true`.
    /// - Returns: An array of subsequences, split from this collection's
    ///   elements.