NSString（十六进制）转换为字节

本文介绍了NSString（十六进制）转换为字节的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

Objective-C中有没有将十六进制字符串转换为字节的方法？例如 @1156FFCD3430AA22到无符号字符数组{0x11，0x56，0xFF，...} 。

解决方案

$ b我可以想到的最快的NSString类别实现$ b

   - （NSData *）dataFromHexString {
 const char * chars = [self UTF8String]; 
 int i = 0，len = self.length; 
 
 NSMutableData * data = [NSMutableData dataWithCapacity：len / 2]; 
 char charChar [3] = {'\0'，'\0'，'\0'}; 
 unsigned long wholeByte; 
 
 while（i< len）{
 byteChars [0] = chars [i ++]; 
 byteChars [1] = chars [i ++]; 
 wholeByte = strtoul（byteChars，NULL，16）; 
 [data appendBytes：& wholeByte length：1]; 
} 
 
返回数据; 
}

它比wookay的解决方案快8倍。 NSScanner非常慢。

Is there any method in Objective-C that converts a hex string to bytes? For example @"1156FFCD3430AA22" to an unsigned char array {0x11, 0x56, 0xFF, ...}.

解决方案

Fastest NSString category implementation that I could think of (cocktail of some examples):

- (NSData *)dataFromHexString {
    const char *chars = [self UTF8String];
    int i = 0, len = self.length;

    NSMutableData *data = [NSMutableData dataWithCapacity:len / 2];
    char byteChars[3] = {'\0','\0','\0'};
    unsigned long wholeByte;

    while (i < len) {
        byteChars[0] = chars[i++];
        byteChars[1] = chars[i++];
        wholeByte = strtoul(byteChars, NULL, 16);
        [data appendBytes:&wholeByte length:1];
    }

    return data;
}

It is close to 8 times faster than wookay's solution. NSScanner is quite slow.

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