Swift - 与外设连接时的字符处理（普通字符串-十六进制互转）

2018-07-10

tips：与外部设备通信难免会遇到字符间互转的问题，普通字符串-十六进制互转是很多app与设备连接时会采用的方案，在网上看到oc版的，于是有了下面的的swift版，亲测可用，不足之处希望能留言告知，谢谢

/// 十六进制转换为普通字符串的。

func stringfromHexStr() -> String {

        var bytes = [UInt8]()

        var dataBStr : String = ""

        for (index, _) in self.enumerated(){

            let fromIndex = index*2

            let toIndex = index*2 + 1

            if toIndex > (self.count - 1) {

                break

            }

            let hexCharStr = self.subString(fromIndex, length: 2)

            var r:CUnsignedInt = 0

            Scanner(string: hexCharStr).scanHexInt32(&r)

            bytes.append(UInt8(r))

        }

        dataBStr = String.init(data: Data(bytes: bytes), encoding: String.Encoding.ascii)!

        return dataBStr

    }

///普通字符串转换为十六进制的。

func stringToHexString() -> String {

        let strData = self.data(using: String.Encoding.utf8)

        let bytes = strData?.withUnsafeBytes {

            [UInt8](UnsafeBufferPointer(start: $0, count: (strData?.count)!))

        }

        var sumString : String = ""

        for byte in bytes! {

            let newString = String(format: "%x",byte&0xff)

            if newString.count == 1 {

                sumString = String(format: "%@0%@",sumString,newString)

            }else{

                sumString = String(format: "%@%@",sumString,newString)

            }

        }

        

        return sumString

    }

补充oc的对照版

///普通字符串转换为十六进制的。

\+ (NSString *)hexStringFromString:(NSString *)string{

    NSData *myD = [string dataUsingEncoding:NSUTF8StringEncoding];

    Byte *bytes = (Byte *)[myD bytes];

    //下面是Byte 转换为16进制。

    NSString *hexStr=@"";

    for(int i=0;i<[myD length];i++)

    {

        NSString *newHexStr = [NSString stringWithFormat:@"%x",bytes[i]&0xff];///16进制数

        if([newHexStr length]==1)

            hexStr = [NSString stringWithFormat:@"%@0%@",hexStr,newHexStr];

        else

            hexStr = [NSString stringWithFormat:@"%@%@",hexStr,newHexStr];

    }

    return [NSString stringWithFormat:@"%@0d0a",hexStr];

}

/// 十六进制转换为普通字符串的。

\+ (NSString *)stringFromHexString:(NSString *)hexString {

    

    char *myBuffer = (char *)malloc((int)[hexString length] / 2 + 1);

    bzero(myBuffer, [hexString length] / 2 + 1);

    for (int i = 0; i < [hexString length] - 1; i += 2) {

        unsigned int anInt;

        NSString * hexCharStr = [hexString substringWithRange:NSMakeRange(i, 2)];

        NSScanner * scanner = [[NSScanner alloc] initWithString:hexCharStr];

        [scanner scanHexInt:&anInt];

        myBuffer[i / 2] = (char)anInt;

    }

    NSString *unicodeString = [NSString stringWithCString:myBuffer encoding:4];

//    NSLog(@"------字符串=======%@",unicodeString);

    return unicodeString;

}