Swift 4通过提供多行字符串文字支持解决了这个问题。要开始字符串字面量，添加三个双引号(" " " ")并按回车键，按回车键后开始写带有任何变量的字符串，换行符和双引号，就像你在记事本或任何文本编辑器中写的那样。要结束多行字符串文字再次写入(" " ")在新行。

参见下面的例子

     let multiLineStringLiteral = """
    This is one of the best feature add in Swift 4
    It let’s you write “Double Quotes” without any escaping
    and new lines without need of “\n”
    """

print(multiLineStringLiteral)

我写了一个小扩展。

extension String {

    init(swiftLintMultiline strings: String...) {
        self = strings.reduce("", +)
    }
}

你可以这样使用它:

String(swiftLintMultiline:
    "Lorem ipsum dolor sit amet, consectetur adipiscing",
    "elit. Ut vulputate ultrices volutpat. Vivamus eget",
    "nunc maximus, tempus neque vel, suscipit velit.",
    "Quisque quam quam, malesuada et accumsan sodales,",
    "rutrum non odio. Praesent a est porta, hendrerit",
    "lectus scelerisque, pharetra magna. Proin id nulla",
    "pharetra, lobortis ipsum sit amet, vehicula elit. Nulla",
    "dapibus ipsum ipsum, sit amet congue arcu efficitur ac. Nunc imperdi"
)

从Swift 4.0开始，可以使用多行字符串，但有一些规则:

你需要用三个双引号"""来开始和结束字符串。 你的字符串内容应该从它自己的行开始。 结尾的"""也应该在自己的行上开始。

除此之外，你就可以开始了!这里有一个例子:

let longString = """
When you write a string that spans multiple
lines make sure you start its content on a
line all of its own, and end it with three
quotes also on a line of their own.
Multi-line strings also let you write "quote marks"
freely inside your strings, which is great!
"""

查看Swift 4的新功能以获得更多信息。

Swift 4通过提供多行字符串文字支持解决了这个问题。要开始字符串字面量，添加三个双引号(" " " ")并按回车键，按回车键后开始写带有任何变量的字符串，换行符和双引号，就像你在记事本或任何文本编辑器中写的那样。要结束多行字符串文字再次写入(" " ")在新行。

参见下面的例子

     let multiLineStringLiteral = """
    This is one of the best feature add in Swift 4
    It let’s you write “Double Quotes” without any escaping
    and new lines without need of “\n”
    """

print(multiLineStringLiteral)

Swift 4支持多行字符串字面值。除了换行符，它们还可以包含未转义的引号。

var text = """
    This is some text
    over multiple lines
    """

旧版本的Swift不允许你在多行上有一个字面值，但你可以在多行上添加字面值:

var text = "This is some text\n"
         + "over multiple lines\n"

下面是一个简单的实现(Swift 5.4+)，使用resultBuilder来清理语法!

@resultBuilder
public struct StringBuilder {
    public static func buildBlock(_ components: String...) -> String {
        return components.reduce("", +)
    }
}

public extension String {
    init(@StringBuilder _ builder: () -> String) {
        self.init(builder())
    }
}

用法:

String {
    "Hello "
    "world!"
} 
// "Hello world!"