Extract subclass

// Animal.h
@interface Animal : NSObject
- (void)meow;
- (void)run;
- (void)eat;
@end
// Animal.m
@implementation Animal {
}
// This method will be moved
// to a subclass
- (void)meow{
    NSLog(@"Meow!");
}
- (void)run {
    NSLog(@"I am running");
}
- (void)eat {
    NSLog(@"I am eating");
}
@end

// New subclass
// Cat.h
@interface Cat : Animal
- (void)meow;
@end
// Cat.m
@implementation Cat {
}
- (void)meow{
    NSLog(@"Meow!");
}
@end

// The Animal class
// Animal.h
@interface Animal : NSObject
- (void)run;
- (void)eat;
@end
// Animal.m
@implementation Animal {
}
- (void)run {
    NSLog(@"I am running");
}
- (void)eat {
    NSLog(@"I am eating");
}
@end