工厂模式 – Objective-C中的示例

http://www.oodesign.com/factory-pattern.html

这些例子都是用Java编写的,我不是一个非常强大的Java程序员.我大多不了解构造函数产品… = cClass … String.class行.我想我已经有了“概念”,但这两个代码块类似吗？

此外,Cocoa Foundation中是否有一个使用这种模式的例子？我唯一能想到的是在UIKit中针对UITableView注册单元类.

Java的：

class ProductFactory
{
    private HashMap m_RegisteredProducts = new HashMap();

    public void registerProduct (String productID,Class productClass)
    {
        m_RegisteredProducts.put(productID,productClass);
    }

    public Product createProduct(String productID)
    {
        Class productClass = (Class)m_RegisteredProducts.get(productID);
        Constructor productConstructor = cClass.getDeclaredConstructor(new Class[] { String.class });
        return (Product)productConstructor.newInstance(new Object[] { });
    }
}

Objective-C的：

@interface ProductFactory : NSObject

- (void)registerProduct:(Class)productClass withIdentifier:(NSString *)identifier;
- (id)newProductForIdentifier:(NSString *)identifier;

@end

@interface ProductFactory();

@property (strong,nonatomic) NSMutableDictionary *registeredProducts;

@end

@implementation ProductFactory

- (id)init
{
    self = [super init];
    if (self) {
        _registeredProducts = [NSMutableDictionary dictionary];
    }

    return self;
}

- (void)registerProduct:(Class)productClass withIdentifier:(NSString *)identifier
{
    self.registeredProducts[identifier] = NSStringFromClass(productClass);
}

- (id)newProductForIdentifier:(NSString *)identifier
{
    NSString *classString = self.registeredProducts[identifier];
    Class productClass = NSClassFromString(classString);

    return [[productClass alloc] init];
}

@end