我怎么能在多行分割字符串,如下面?
var text:String = "This is some text
over multiple lines"
我怎么能在多行分割字符串,如下面?
var text:String = "This is some text
over multiple lines"
当前回答
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!"
其他回答
正如litso所指出的,在一个表达式中重复使用+-操作符会导致Xcode Beta挂起(刚刚用Xcode 6 Beta 5检查过):Xcode 6 Beta无法编译
目前,多行字符串的另一种替代方法是使用一个字符串数组,并将其压缩为+:
var text = ["This is some text ",
"over multiple lines"].reduce("", +)
或者,可以更简单地使用join:
var text = "".join(["This is some text ",
"over multiple lines"])
另一种方法是,如果你想使用带有预定义文本的字符串变量,
var textFieldData:String = "John"
myTextField.text = NSString(format: "Hello User, \n %@",textFieldData) as String
myTextField.numberOfLines = 0
一种方法是将标签文本设置为attributedText,并更新字符串变量以包含换行符的HTML (<br />)。
例如:
var text:String = "This is some text<br />over multiple lines"
label.attributedText = text
输出:
This is some text
over multiple lines
希望这能有所帮助!
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"
下面是一个代码片段,用n个字符分隔字符串:
//: A UIKit based Playground for presenting user interface
import UIKit
import PlaygroundSupport
class MyViewController : UIViewController {
override func loadView() {
let str = String(charsPerLine: 5, "Hello World!")
print(str) // "Hello\n Worl\nd!\n"
}
}
extension String {
init(charsPerLine:Int, _ str:String){
self = ""
var idx = 0
for char in str {
self += "\(char)"
idx = idx + 1
if idx == charsPerLine {
self += "\n"
idx = 0
}
}
}
}