原型

//Prototype
@protocol Shape <NSObject>
@property (nonatomic, copy) NSString *color;

- (id<Shape>)clone;
@end

//ConcretePrototype
@interface Square : NSObject <Shape>
- (instancetype)initWithColor:(NSString *)color;
@end

@implementation Square

//@synthesize is needed: the property comes from the protocol,
//not from @interface
@synthesize color;

- (instancetype)initWithColor:(NSString *)value {
    self = [super init];
    if (self) {
        color = [value copy];
    }
    return self;
}

- (id<Shape>)clone {
    return [[Square alloc] initWithColor:color];
}
@end

//Client
@interface ShapeMaker : NSObject
- (instancetype)initWithShape:(id<Shape>)shape;
- (id<Shape>)makeShape;
@end

@implementation ShapeMaker {
    id<Shape> _shape;
}

- (instancetype)initWithShape:(id<Shape>)shape {
    self = [super init];
    if (self) {
        _shape = shape;
    }
    return self;
}

- (id<Shape>)makeShape {
    return [_shape clone];
}
@end

Square *square = [[Square alloc] initWithColor:@"Red"];
ShapeMaker *maker = [[ShapeMaker alloc] initWithShape:square];

id<Shape> square1 = [maker makeShape];
Square *square2 = (Square *)[maker makeShape];

NSLog(@"%@", square1.color);
NSLog(@"%@", square2.color);