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

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

在Swift 5中，apple引入了使用#符号的原始字符串。

例子:

print(#"My name is "XXX" and I'm "28"."#)
let name = "XXX"
print(#"My name is \#(name)."#)

符号#必须在\后面。常规的\(name)将被解释为字符串中的字符。

你也可以在Swift中使用stringByAppendingFormat。

var finalString : NSString = NSString(string: "Hello")
finalString = finalString.stringByAppendingFormat("%@", " World")
print(finalString) //Output:- Hello World
finalString = finalString.stringByAppendingFormat("%@", " Of People")
print(finalString) //Output:- Hello World Of People

这也会起作用:

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

\ 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。