NSString <> unicode, file read

unicode_file.m

#import <Foundation/Foundation.h>
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>
@implementation NSString (test)
+ (NSString *)unicodeStringWithString:(NSString *)string {
    NSString *result = [NSString string];
    for (int i = 0; i < [string length]; i++) {
        result = [result stringByAppendingFormat:@"\\u%04x", [string characterAtIndex:i]];
        /*
         因为 Unicode 用 16 个二进制位（即 4 个十六进制位）表示字符,对于小于 0x1000 字符要用 0 填充空位,
         所以使用 %04x 这个转换符, 使得输出的十六进制占 4 位并用 0 来填充开头的空位.
         */
    }
    return result;
}

+ (NSString *)stringWithUnicodeString:(NSString *)string {
    NSArray *strArray = [[string substringFromIndex:2] componentsSeparatedByString:@"\\u"];
    NSString *result = [NSString string];
    for (NSString *str in strArray) {
        NSString *tmpStr = [@"0x" stringByAppendingString:str];
        unichar c = strtoul([tmpStr UTF8String], 0, 0);
        /*
         上面两行也可以写成下面一行：
         unichar c = strtoul([str UTF8String], 0, 16);
         */
        result = [result stringByAppendingString:[NSString stringWithCharacters:&c length:1]];
    }
    return result;
}
@end

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        uint16 buffer[1024];
        long position=0x20f000;
        int numOfUnichar=15;
        NSString *binaryPath=@"/Applications/xxx.app/Contents/MacOS/xxx";
        const char *binary_path=[binaryPath cStringUsingEncoding:NSUTF8StringEncoding];
        struct stat s;
        if(stat(binary_path, &s) != 0) {
            perror(binary_path);
            NSLog(@"binary path wrong");
            exit(1);
        }
        FILE *binaryFile = fopen(binary_path, "r+");
        if(!binaryFile) {
            printf("Couldn't open file %s\n", binary_path);
            exit(1);
        }
        fseek(binaryFile, position, SEEK_SET);//0x00010020ecde
        fread(&buffer, sizeof(buffer), 1, binaryFile);
        fclose(binaryFile);
        unichar a;
        NSMutableString *muString=[NSMutableString string];
        for (int i=0; i<numOfUnichar; i++) {
            a=buffer[i];
            [muString appendString:[NSString stringWithCharacters:&a length:1]];
        }
        NSLog(@"%@",muString);
    }
    return 0;
}