NSMutableString vs NSString

1

So, the documentation says:

Why am I able to change the value of the NSString object in this code? I feel like I’m missing something.


#import <Foundation/NSString.h>
#import <Foundation/NSObject.h>
#import <Foundation/NSAutoreleasePool.h>

int main(int argc, char *argv[])
{
	NSAutoreleasePool *pool = [NSAutoreleasePool new];
	
	NSString *myStr = @"I can haz programburger";
	
	myStr = @"banana";
	
	printf("
 %s 
", [myStr UTF8String]); //Returns "banana"
	
	[pool release];
	
	return 0;
}