How do I pass a string as a method parameter in objective-c?

Question

I am trying to write my first class in objective-c and i want to pass an NSString object as a parameter in a method of the class, however i get an error saying that "can not use an object as parameter to a method". So my question is how do you pass a string as a parameter to a method? here is my code tht i am trying to get to work:

#import <Foundation/Foundation.h>

@interface Car
{
    NSString *color;
    NSString *make;
    int year;
}    

- (void) print;
- (void) setColor: (NSString) c;
- (void) setMake: (NSString) m;
- (void) setYear: (int) y;


@end

@implementation Car

- (void) print
{
    NSLog(@"The $d Ford %@ is $@.", year, make, color);
}

- (void) setColor: (NSString) c
{
    color=c;
}

- (void) setMake: (NSString) m
{
    make=m;
}

- (void) setYear: (int) y
{
    year=y;
}


@end



int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

    Car *car= [Car new];

    [car setColor:@"blue"];
    [car setMake:@"Bronco"];
    [car setYear:1992]

    [car print];
    [car release];

    [pool drain];
    return 0;
}