swift String

    /**字符串操作*/
    str = str.uppercased()//大写
    print("\(str)")
    str = str.lowercased()//小写
    print("\(str)")
    str = str.localizedCapitalized//首字母大写
    print("\(str)")
    str.insert("g", at: str.startIndex)//增加
    print("\(str)")
    str.remove(at: str.startIndex)//移除
    print("\(str)")
    str = str.replacingOccurrences(of: "d", with: "b")//替换
    print("\(str)")
    let str5 = "hfehueufeuf"
    str = str + str5//拼接
    print("\(str)")
    str = String(str.reversed())//倒序
    print("\(str)")
    /**读取范围字符串*/
    str = String(str[str.startIndex..<str.endIndex])
    print("\(str)")
    str = String(str[String.Index.init(encodedOffset: 1)..<String.Index.init(encodedOffset: 4)])
    print("\(str)")
    /**判断是否包含*/
    if str.hasPrefix("a") {
        print("存在a开头")
    }
    if str.hasSuffix("ee") {
        print("存在ee结尾")
    }
    if str.contains("a") {
        print("存在a")
    }
    let range = str.range(of: "bbccdd")
    if range != nil {
        print("包含bbccdd")
    }
    //包含某个字符
    var index = 0
    for c1 in str {
        if(c1 == "a"){
            index = index + 1
        }
    }
    print("包含\(index)个a")
    //包含某个字符串
    var index1 = 0
    while(true) {
        let range1 = str.range(of: "aa")
        if(range1 != nil){
            index1 = index1 + 1
            str = String(str[(range1?.upperBound)! ..< str.endIndex])
        }
        else{
            break
        }
    }
    print("包含\(index1)个aa")
    /**分割字符串*/
    let arr1 = str.split(separator: "a")
    for c in arr1 {
        print("\(c)")
    }