Swift3 字符串常用操作

以下有关字符串的常用操作都可直接复制到Xcode中进行验证,如发现错误,请在评论区留言指正!

1.字符串的定义

var str1="hello, swift." //字符串变量 相当于OC中的可变字符串

let str2="hello, swift." //字符串常量 相当于OC中的不可变字符串

let str3="" //空字符串

let str4=String() //空字符串

---

2.字符串的连接

2.1 使用+连接符

//字符串的连接

let str1 = "hello"

let str2 = "swift"

let str3 = str1 + str2

print(str3)

2.2 使用字符串插值(该方法也可用于字符串与其他类型值的连接)

let str1 = "hello"

let str2 = "swift"

let str4 = "\(str1)\(str2)"

print(str4)

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3.字符串枚举字符

let str="伊丽莎白"

for ch in str.characters{

print(ch)

}

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4.字符串长度

//字符串的长度

let str1 = "hello swift"

print(str1.characters.count)

---

5.字符串的比较

//字符串的比较 判断两个字符串是否相等

let str1 = "hello"

let str2 = "hello"

if str1 == str2{

print("两个字符串是相等的")

}else{

print("两个字符串不相等")

}

---

6.判断是否包含子串

//判断字符串是否包含子串

let str1 = "hello swift"

let str2 = "SWIFT"

let lmrRange = str1.range(of: str2)//正向查找

let rmlRange = str1.range(of: str2, options: .backwards)//反向查找

let ignore_Text_transformRange = str1.range(of:str2, options: .caseInsensitive, range:nil , locale:nil)//忽略大小写

if ignore_Text_transformRange != nil{

print("str1中包含着子串")

}else{

print("str1中不包含子串")

}

---

7.首字母大写capitalized

//首字母大写

let str1 = "hello"

let str2 = str1.capitalized

print(str2)

---

8.字符串全部转为大写uppercase

//字符串转为大写

let str1 = "hello"

let str2 = str1.uppercased()

print(str2)

---

9.字符串全部转为小写lowrecase

//字符串转为小写

let str1 = "HELLO"

let str2 = str1.lowercased()

print(str2)

---

10.按照下标截取子字符串

//字符串截取子字符串

let str1 = "HELLO swift"

let str2 = str1.substring(from: str1.startIndex)//从头开始截取

let str3 = str1.substring(to: str1.endIndex)//截取到尾部

//获取截取范围

let i = str1.index(str1.startIndex, offsetBy: 4)

let j = str1.index(str1.startIndex, offsetBy: 8)

let str4 = str1.substring(with: i..

print(str2)

print(str3)

print(str4)

---

11.字符串修整trim

var str1 = "  !hi?  !23?  !???"

let str2 = str1.trimmingCharacters(in: NSCharacterSet.whitespaces)//"!hi  !23  !"去掉两边的空格

let str3 = str2.trimmingCharacters(in: NSCharacterSet(charactersIn:"!?") as CharacterSet)//"hi  !23" 去掉两边的空格和‘!’ ，把 字符串中的每个字符进行了分解并去除

print(str3)

注意:这里是只能修整两边的,只能修整两边的

---

12.字符串分解split

//字符串的分解split

var str1 = "hello,swift,you,change,so,fast,!"

let strArray1:[String] = str1.components(separatedBy: ",")

for index in strArray1{

print(index)

}

var str2 = "hello,swift?goodbye,swift?!"

let strArray2:[String] = str2.components(separatedBy: NSCharacterSet(charactersIn:",?") as CharacterSet)

for index in strArray2{

print(index)

}

---

13.字符串替换replace

//字符串替换replace

var str1 = "hello Object-C,you change so fast!"

let str2 = str1.replacingOccurrences(of: "Object-C", with: "swift")//字符串替换字符串

let i = str1.index(str1.startIndex, offsetBy: 6)

let j = str1.index(str1.startIndex, offsetBy: 14)

let str3 = str1.replacingCharacters(in: i..

let str4 = str1.replacingOccurrences(of: "OBJECt-C", with: "SWIFT", options: .caseInsensitive, range: nil)//忽略大小写替换

print(str2)

print(str3)

print(str4)