将NSData序列化为十六进制字符串的最佳方法 [英] Best way to serialize an NSData into a hexadeximal string

问题描述

我正在寻找一种很好的可可方式将NSData对象序列化为十六进制字符串。我的想法是将用于通知的deviceToken序列化，然后再将其发送到我的服务器。

I am looking for a nice-cocoa way to serialize an NSData object into a hexadecimal string. The idea is to serialize the deviceToken used for notification before sending it to my server.

我有以下实现，但我认为必须有一些更短更好的方法要做到这一点。

I have the following implementation, but I am thinking there must be some shorter and nicer way to do it.

+ (NSString*) serializeDeviceToken:(NSData*) deviceToken
{
    NSMutableString *str = [NSMutableString stringWithCapacity:64];
    int length = [deviceToken length];
    char *bytes = malloc(sizeof(char) * length);

    [deviceToken getBytes:bytes length:length];

    for (int i = 0; i < length; i++)
    {
        [str appendFormat:@"%02.2hhX", bytes[i]];
    }
    free(bytes);

    return str;
}

推荐答案

这是一个适用于的类别我写的NSData。它返回表示NSData的十六进制NSString，其中数据可以是任意长度。如果NSData为空，则返回空字符串。

This is a category applied to NSData that I wrote. It returns a hexadecimal NSString representing the NSData, where the data can be any length. Returns an empty string if NSData is empty.

NSData + Conversion.h

#import <Foundation/Foundation.h>

@interface NSData (NSData_Conversion)

#pragma mark - String Conversion
- (NSString *)hexadecimalString;

@end

NSData + Conversion.m

#import "NSData+Conversion.h"

@implementation NSData (NSData_Conversion)

#pragma mark - String Conversion
- (NSString *)hexadecimalString {
    /* Returns hexadecimal string of NSData. Empty string if data is empty.   */

    const unsigned char *dataBuffer = (const unsigned char *)[self bytes];

    if (!dataBuffer)
        return [NSString string];

    NSUInteger          dataLength  = [self length];
    NSMutableString     *hexString  = [NSMutableString stringWithCapacity:(dataLength * 2)];

    for (int i = 0; i < dataLength; ++i)
        [hexString appendString:[NSString stringWithFormat:@"%02lx", (unsigned long)dataBuffer[i]]];

    return [NSString stringWithString:hexString];
}

@end

用法：

NSData *someData = ...;
NSString *someDataHexadecimalString = [someData hexadecimalString];

这可能比调用 [someData description] 然后剥离空格，< s和>。剥离字符只是感觉太hacky。此外，您永远不会知道Apple将来是否会更改NSData的 -description 的格式。

This is "probably" better than calling [someData description] and then stripping the spaces, <'s, and >'s. Stripping characters just feels too "hacky". Plus you never know if Apple will change the formatting of NSData's -description in the future.

注意：我已经让人们联系我这个答案的代码许可。我特此将我在此公共领域的答案中公布的代码的版权保留给我。

NOTE: I have had people reach out to me about licensing for the code in this answer. I hereby dedicate my copyright in the code I posted in this answer to the public domain.

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