Swift 对字符串进行追加、插入、替换、删除等操作代码示范

// 字符串追加
var str1 = "Hello,"
str1 += " Swift"
print(str1) // "Hello, Swift"

// 字符串插入
var str2 = "How are you?"
str2.insert(contentsOf: " Lily", at: str2.index(str2.endIndex, offsetBy: -1))
print(str2) // "How are you, Lily?"

// 字符串替换
var str3 = "I love Playgrounds!"
str3 = str3.replacingOccurrences(of: "Playgrounds", with: "Swift")
print(str3) // "I love Swift!"

// 字符串删除
var str4 = "I don't want this"
str4.removeLast(5)
print(str4) // "I don't want"