iOS设计模式 (三) 工厂模式之工厂方法

工厂模式：工厂方法

• 定义一个用于创建对象的接口，让子类决定实例化哪一个类。工厂方法使一个类的实例化延迟到其子类。

• 工厂方法UML

  
  2.png

demo实现

• ColorViewGenerator（抽象类）

#import <Foundation/Foundation.h>
#import "RedView.h"
#import "BlueView.h"

@interface ColorViewGenerator : NSObject

- (ColorView *)colorViewWithFrame:(CGRect)rect;

@end
#import "ColorViewGenerator.h"

@implementation ColorViewGenerator

- (ColorView *)colorViewWithFrame:(CGRect)rect
{
   return [[ColorView alloc] initWithFrame:rect];
}

@end

• RedViewGenerator（类）

#import "ColorViewGenerator.h"

@interface RedViewGenerator : ColorViewGenerator

@end

#import "RedViewGenerator.h"

@implementation RedViewGenerator

- (ColorView *)colorViewWithFrame:(CGRect)rect
{
    return [[RedView alloc] initWithFrame:rect];
}

@end

• BlueViewGenrator（product类）

#import "ColorViewGenerator.h"

@interface BlueViewGenrator : ColorViewGenerator

@end
#import "BlueViewGenrator.h"

@implementation BlueViewGenrator

- (ColorView *)colorViewWithFrame:(CGRect)rect
{
    return [[BlueView alloc] initWithFrame:rect];
}

@end

• ColorView 类（product 类）

#import <UIKit/UIKit.h>

@interface ColorView : UIView

@end

#import "ColorView.h"

@implementation ColorView

- (instancetype)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        self.backgroundColor = [UIColor grayColor];
    }
    return self;
}
@end

• RedView 类（子类）

#import "ColorView.h"

@interface RedView : ColorView

@end
#import "RedView.h"

@implementation RedView

- (instancetype)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        self.backgroundColor = [UIColor redColor];
        UIImage *backGroundImage = [UIImage imageNamed:@"2"];
        UIImageView *backImageView = [[UIImageView alloc] initWithImage:backGroundImage];
        [self addSubview: backImageView];
    }
    return self;
}

@end

• BlueView 子类

#import "ColorView.h"

@interface BlueView : ColorView

@end

#import "BlueView.h"

@implementation BlueView

- (instancetype)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        self.backgroundColor = [UIColor blueColor];
        UIImage *backGroundImage = [UIImage imageNamed:@"3"];
        UIImageView *backImageView = [[UIImageView alloc] initWithImage:backGroundImage];
        [self addSubview: backImageView];
    }
    return self;
}
@end

• ViewController 类

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController
@end
#import "ViewController.h"
#import "BlueViewGenrator.h"
#import "RedViewGenerator.h"
#import "RedView.h"
#import "BlueView.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    RedView *redview = (RedView *)[[RedViewGenerator alloc] colorViewWithFrame:self.view.bounds];
    [self.view addSubview: redview];
    
    BlueView *blueView = (BlueView *) [[BlueViewGenrator alloc] colorViewWithFrame:self.view.bounds];
    [self.view addSubview: blueView];
    
}

@end

源代码详见：https://github.com/defuliu/FactoryPatterns.git