读取NsArray的十六进制值返回0

Question

在我的Objective-C代码中，我收到了一个包含十六进制值的文件。我读取该文件并将前几个字节转换为NSarray，然后尝试阅读以执行计算。 The conversion seems to work, this is what it looks like:

    NSBundle *mainBundle = [NSBundle mainBundle];
    NSFileHandle *fh;
    NSData *wordBuffer;
    NSMutableArray *myByteArray = [NSMutableArray new];

    NSString *filePath = [mainBundle pathForResource:@"data" ofType:@"txt"];
    fh = [NSFileHandle fileHandleForReadingAtPath: filePath];

    while ((wordBuffer = [fh readDataOfLength:1]) && [wordBuffer length] ) 
    {
        [myByteArray addObject:[self hexStringForData:wordBuffer]];
    }
    return myByteArray];
}

The problem is when I read back from that Array, values that use letter in hexadecimal are completely wrong, as if objective-C ignored the letters. FF返回0，7b返回7，依此类推。

So I get the myByteArray back from the init function, store it in response and try to read it like this:

unsigned long test = [response[1] unsignedLongValue];
NSLog(@"Value in unsigned long: %lu", test);

This crashed the app because of an NSInvalidArgumentException cause by the selector '卢'，但我不明白为什么。

unsigned int test = [[answerHeader response][1] unsignedIntValue];
NSLog(@"Value in unsigned long: %u", test);

this returns 0

NSString *str = response[1];
unsigned long red = strtoul([str UTF8String], 0, 16);
NSLog(@"converted long: %lu", red);

this returns 255

I don't think I can really afford to read every single bytes like that (it looks more expensive that array[2] intValue). 发生了什么，我该如何解决？ 提前致谢 ！

Answer 1

我建议您将文件读为字符串：
read txt file into string

NSStringEncoding encoding;
NSError *error;
NSString *fileContents = [[[NSString alloc] initWithContentsOfFile:filePath
                                                      usedEncoding:&encoding
                                                             error:&error]

then
parse hex to in int

unsigned result = 0;
NSScanner *scanner = [NSScanner scannerWithString:@"#01FFFFAB"];

[scanner setScanLocation:1]; // bypass '#' character
[scanner scanHexInt:&result];