Possible Duplicate:
objc warning: “descartar qualificadores do tipo de alvo do ponteiro”

Estou com problemas para converter umNSString para uma string C.

const char *input_image = [[[NSBundle mainBundle] pathForResource:@"iphone" ofType:@"png"] UTF8String];
const char *output_image = [[[NSBundle mainBundle] pathForResource:@"iphone_resized" ofType:@"png"] UTF8String];

const char *argv[] = { "convert", input_image, "-resize", "100x100", output_image, NULL };

// ConvertImageCommand(ImageInfo *, int, char **, char **, MagickExceptionInfo *);
// I get a warning: Passing argument 3 'ConvertImageCommand' from incompatible pointer type.
ConvertImageCommand(AcquireImageInfo(), 2, argv, NULL, AcquireExceptionInfo());

Também quando depuroargv não parece certo. Vejo valores como:

argv[0] contains 99 'c' // Shouldn't this be "convert"?
argv[1] contains 0 '\100' // and shouldn't this be the "input_image" string?