OC 十六進制字符串轉二進制字符串

//十六進制轉換爲二進制
+ (NSString *)getBinaryByHex:(NSString *)hex {
    NSMutableDictionary *hexDic = [[NSMutableDictionary alloc] initWithCapacity:16];
    [hexDic setObject:@"0000" forKey:@"0"];
    [hexDic setObject:@"0001" forKey:@"1"];
    [hexDic setObject:@"0010" forKey:@"2"];
    [hexDic setObject:@"0011" forKey:@"3"];
    [hexDic setObject:@"0100" forKey:@"4"];
    [hexDic setObject:@"0101" forKey:@"5"];
    [hexDic setObject:@"0110" forKey:@"6"];
    [hexDic setObject:@"0111" forKey:@"7"];
    [hexDic setObject:@"1000" forKey:@"8"];
    [hexDic setObject:@"1001" forKey:@"9"];
    [hexDic setObject:@"1010" forKey:@"A"];
    [hexDic setObject:@"1011" forKey:@"B"];
    [hexDic setObject:@"1100" forKey:@"C"];
    [hexDic setObject:@"1101" forKey:@"D"];
    [hexDic setObject:@"1110" forKey:@"E"];
    [hexDic setObject:@"1111" forKey:@"F"];
    NSString *binary = @"";
    for (int i=0; i<[hex length]; i++) {
        NSString *key = [hex substringWithRange:NSMakeRange(i, 1)];
        NSString *value = [hexDic objectForKey:key.uppercaseString];
        if (value) {
            binary = [binary stringByAppendingString:value];
        }
    }
    return binary;
}