- (void)viewDidLoad {
[super viewDidLoad];
//注意，中文的编码集是Unicode  一个中文有三个字节
_myStr1 = @"wukeng please cheer 我";
 [self transform];
 [self sixthTobyes];
}

1.字符串转数据

 NSData *data = [_myStr1 dataUsingEncoding:NSUTF8StringEncoding];

2.数据转字节数组

Byte *bytes = (Byte *)[data bytes];
for (int i = 0; i < data.length; i++) {
    NSLog(@"%hhu",bytes[i]);
    //字节数组转换成字符
    NSData *d1 = [NSData dataWithBytes:bytes length:i+1];
    NSString *str = [[NSString alloc] initWithData:d1 encoding:NSUTF8StringEncoding];
    NSLog(@"%@",str);
}

3.字节数组转换成16进制数

NSString *hexStr=@"";
for(int i=0;i<[data 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];
}
NSLog(@"bytes 的16进制数为:%@",hexStr);

4.16进制数转换成字节数组

int j=0;
Byte bytes[hexString.length / 2];  
for(int i=0;i<[hexStr length];i++)
{
    int int_ch;  /// 两位16进制数转化后的10进制数
    unichar hex_char1 = [hexStr characterAtIndex:i]; ////两位16进制数中的第一位(高位*16)
    int int_ch1;
    if(hex_char1 >= '0' && hex_char1 <='9')
    {
        int_ch1 = (hex_char1-48)*16;   //// 0 的Ascll - 48
    }
    else if(hex_char1 >= 'A' && hex_char1 <='F')
    {
        int_ch1 = (hex_char1-55)*16; //// A 的Ascll - 65
    }
    else
    {
        int_ch1 = (hex_char1-87)*16; //// a 的Ascll - 97
    }
    i++;
    unichar hex_char2 = [hexStr characterAtIndex:i]; ///两位16进制数中的第二位(低位)
    int int_ch2;
    if(hex_char2 >= '0' && hex_char2 <='9')
    {
        int_ch2 = (hex_char2-48); //// 0 的Ascll - 48
    }
    else if(hex_char1 >= 'A' && hex_char1 <='F')
    {
        int_ch2 = hex_char2-55; //// A 的Ascll - 65
    }
    else   
    {
        int_ch2 = hex_char2-87; //// a 的Ascll - 97  
    }
    int_ch = int_ch1+int_ch2;
    NSLog(@"int_ch=%d",int_ch);
    bytes[j] = int_ch;  ///将转化后的数放入Byte数组里
    j++;
  }
  NSData *newData = [[NSData alloc] initWithBytes:bytes length:hexStr.length / 2];
  NSLog(@"newData=%@",newData);

swift版本的代码建下面

class ViewController: UIViewController {
var myStr = "wukeng cheer please"
override func viewDidLoad() {
    super.viewDidLoad()
    transform()
  }
}

//字符串转数据，数据转字符串，数据转字节数组，字节数组转数据
extension ViewController{
func transform() {
    //字符串转数据
    let d1 = myStr.data(using: .utf8, allowLossyConversion: true)
    print(d1!)
    //数据转换成字符串
    let string = NSString.init(data: d1!, encoding: String.Encoding.utf8.rawValue)
    print(string!)
    //数据转换成字节数组
    let bytes = [UInt8](d1!)
    print(bytes)
    //字节数组转数据
    let mutData = NSMutableData()
    mutData.append(bytes, length: bytes.count)
    print(mutData)
    //字节数组转16进制字符串
    let str2 = bytesToHexStr(bytes: bytes)
    print(str2)
  }
}

extension ViewController{
//字节数组转16进制字符串
func bytesToHexStr(bytes : [UInt8]) -> String {
    var hexStr = ""
    for index in 0...bytes.count-1 {
        let newHexStr = NSString.init(format: "%x", bytes[index]&0xff)
        if newHexStr.length == 1 {
            hexStr = NSString.init(format: "%@0%@", hexStr,newHexStr) as String
        }
        else{
            hexStr = NSString.init(format: "%@%@", hexStr,newHexStr)  as String
        }
    }
    return hexStr
}

}

以上就是一些简单的数据转换希望对大家有帮助。