\ this被用来将一个字符串附加到另一个字符串。

var first = "Hi" 
var combineStr = "\(first) Start develop app for swift"

你也可以试试这个:- +关键字。

 var first = "Hi" 
 var combineStr = "+(first) Start develop app for swift"

试试这段代码。

斯威夫特5:

数组的字符串变成一个单一的字符串

let array = ["Ramana","Meharshi","Awareness","Oneness","Enlightnment","Nothing"]
let joined = array.joined(separator: ",")

var language = "Swift" 
var resultStr = "\(language) is a new programming language"

这也会起作用:

var string = "swift"
var resultStr = string + " is a new Programming Language"

斯威夫特4.2

你也可以使用扩展:

extension Array where Element == String? {
    func compactConcate(separator: String) -> String {
        return self.compactMap {
            if let unwrappedString = $0,
               unwrappedString.isEmpty {
                return nil
            } else {
                return $0
            }
        }
        .joined(separator: separator)
    }
}

Use:

label.text = [m.firstName, m.lastName].compactConcate(separator: " ")

结果:

"The Man"
"The"
"Man"

Xcode不接受与普通字符串一起添加的可选字符串。我写了这个扩展来解决这个问题:

extension String {
    mutating func addString(str: String) {
        self = self + str
    }
}

然后你可以这样称呼它:

var str1: String?
var str1 = "hi"
var str2 = " my name is"
str1.addString(str2)
println(str1) //hi my name is

然而，你现在也可以这样做:

var str1: String?
var str1 = "hi"
var str2 = " my name is"
str1! += str2