将表示HEX值的NSString转换为十六进制（@＆＃34; 0d＆＃34;到0x0d）

Question

我想转换ObjectiveC NSString，其中包含例如string＆＃34; 0d＆＃34;到十六进制值0x0d。最简单的方法是什么？

示例：

NSString *str = @"50";
unsigned char mac[1];
mac[0] = 0x50; //<- how to set mac[0] to 0x50 from "str" string?

Answer 1

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

    NSMutableData *data = [NSMutableData dataWithCapacity:len/2];
    char byteChars[3] = {chars[0],chars[1],'\0'};
    unsigned long wholeByte = strtoul(byteChars, NULL, 16);
    [data appendBytes:&wholeByte length:1];

    return data;
}