如何在NSMutableData的末尾附加3个字节的“ 110”

Question

HERE IS THE CODE->

NSString* message = @"username,password";
NSMutableData *data = [[NSMutableData alloc] initWithData:
                       [message dataUsingEncoding:NSASCIIStringEncoding]];

[data appendBytes:"0x1""0x1""0x0"
               length:3];

I am expecting output -> username,password110

but not getting this.

Answer 1

What you are appending is not bytes, it's a string "0x10x10x0" . The first three characters get appended - specifically, '0' , 'x' , and '1' .

To append three bytes, create a byte array, and append it:

unsigned char suffixBytes[] = {1, 1, 0};
[data appendBytes:suffixBytes length:3];

In one specific case, when all bytes represent character codes of printable characters, you can use a string literal instead:

[data appendBytes:"110" length:3];

This will append character codes of '1' , '1' , and '0' to your data. Assuming ASCII encoding, the values would be {0x31, 0x31, 0x30} .