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iOS Swift4.0 字符串String拼接,裁剪...

iOS Swift4.0 字符串String拼接,裁剪...

作者: _菩提本无树_ | 来源:发表于2018-01-23 10:54 被阅读49次

    前言:4.0的好多都有改变,但是网上的更新很少.所以呢就随手写一下不多说还是直接上代码

    !!!看下面的时候需要注意var和let的区别这里就不详细解释了可以自己去搜一下.

    1.定义字符串

    func definitionString() -> () {
        
        let name = "小龙"//变量字符串
        let m_name = "王"//常量字符串
        let m__name = ""//空的字符串
        let m___name = String()//空的字符串
        print(name,m_name,m__name,m___name);
    
    }
    

    2.字符串拼接

    func StringJoint() -> () {
        let studentNum = "1"//学生的学号
        let studentName = "小龙"//学生的姓名
        print(studentNum+studentName)
        print("\(studentNum):\(studentName)")
        let arr = ["星","期","一"]
        //数组转字符串
        let today = arr.joined(separator: "__")//将数组中的数据通过__连接
        print(today)
        ///其他类型的转string
        let num1 = 10
        let num2 = 12
        let str1 = "\(num1)+\(num2)"
        print(str1)
        
    }
    

    3.枚举字符

    func enumChar() -> () {
        //遍历
        let myStr = "my name is De Shuai Dong 🌺 我的"
        for char in myStr {
            print(char);
        }        
    }
    

    4.获取字符串中指定索引处的字符

    func getStrChar() -> () {
    
        let s:String = "SwiftMineStudy"
        //取从开始的位置数index等于3的字符
        let sub0 = s.index(s.startIndex, offsetBy: 3)
        //取从最后的位置数第二个的字符
        let sub1 = s.index(s.endIndex, offsetBy: -2)
        //从sub0的位置开始数接下来的第二位的字符
        let sub2 = s.index(sub0, offsetBy: 2)
        //同上
        let sub3 = s.index(s.startIndex, offsetBy: 2)
        //取sub0之前的一位字符
        let sub4 = s.index(before: sub0)
        //取sub0之后的一位字符
        let sub5 = s.index(after: sub0)
        //取sub0之前的左右字符串
        let sub6 = s.prefix(upTo: sub0)
        //取sub0之后的所有字符串
        let sub7 = s.suffix(from: sub0)
        //拼接,字符需转为字符串
        //lableTest.text = String(s[sub0])+String(s[sub1])+sub6
        //反转字符串
        //lableTest.text = String(s.reversed())
        print(s[sub0],s[sub1],s[sub2],s[sub3],s[sub4],s[sub5],sub6,sub7)
        //字符串换行
        let name = """
                        qweqwe
                        qweqwe
                        sdfsdfsdf
                   """
        print(name)
        //字符串是否为空
        if s.isEmpty {
            print("为空")
        }else{
            print("不为空")
        }
        //字符串区间截取
        //方法一
        let snowy = " Let it snow! "
        let nsrange = NSRange(location: 3, length: 6)
        let start = snowy.index(snowy.startIndex, offsetBy: nsrange.lowerBound)
        let end = snowy.index(snowy.startIndex, offsetBy: nsrange.upperBound)
        let substringRange = start..<end
        print(snowy[substringRange])
        //方法二
        let values = "abcdefg"
        let startSlicingIndex = values.index(values.startIndex, offsetBy: 3)
        let endSlicingIndex = values.index(values.endIndex, offsetBy: -2)
        let subvalues = values[startSlicingIndex...endSlicingIndex] // One-sided Slicing
        //        Range
        print(subvalues)
      
        //字符串前面是否有
        if values .hasPrefix("a") {
            print("有")
        }else{
            print("无")
        }
        //字符串后面是否有
        if values.hasSuffix("a") {
            print("有")
        }else{
            print("没有")
        }
    
    }
    

    5.字符串的其他用法

    func 字符串的其他用法() -> () {
        //注意这里是变量
        var str:String = "av,1,2,3,4,5,6,7,8,a,b,c,d,e"
        //获取字符串长度
        print(str.count)
        if str.count>3 {
            print("长度大了")
        }
        //去除字符串中的特殊字符 只能去除一个
        str.remove(at: str.index(of: ",")!)
        print(str)
        //字符串转数组
        let arr = str.components(separatedBy: ",")
        print(arr)
        //转大写
        let str1 = str.uppercased()
        print(str1)
        //转小写
        let str2 = str.lowercased()
        print(str2)
        //每个单词首字母大写
        let str3 = str.capitalized
        print(str3)
        //字符串替换
        let str4 = str.replacingOccurrences(of: ",", with: "")
        print(str4)
        //判断是否包含某个字符串
        if str.range(of: "av") != nil {
            print("包含")
        }
        if str == str3 {
            print("相等")
        }else{
            print("不相等")
        }
        //转int
        let str5 = "123"
        let intNum:Int = Int(str5)!
        print(intNum + 3)
        
        
    }
    

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