Question

I’m trying to get this loop to free all of the memory it uses, but it still gobbles up RAM pretty quickly. Hopefully someone can tell me how I can get the strings deallocating as they should. Basically, the loop writes doubles to a text file, and sometimes it has to write several megabytes of them.

for (int i = 0; i < number_of_samples; i++)
{
    if (print_str == nil)
    {
        print_str = [[NSMutableString alloc] init];
    }

    NSString* add_str = [[NSString alloc] initWithFormat:@"\n%0.06f", number_of_seconds/number_of_samples*i];
    [print_str appendString:add_str];
    [add_str release];

    for (int g = 0; g < number_of_channels; g++)
    {
        add_str = [[NSString alloc] initWithFormat:@"\t%f", data_buffer[g + i*number_of_channels]];
        [print_str appendString:add_str];
        [add_str release];
    }

    if (i % 100 == 0 && i != 0)
    {
        fprintf(c_file_handle, "%s", [print_str UTF8String]);
        [print_str release];
        print_str = nil;
    }
}

Answer 1

The only thing you can do with the string is not using the print_str cause it still holds all the strings and occupies memory. Use “a” option in fopen to append data to the file and append the formatted string add_str to the file instead of adding it to the memory buffer.