模板模式

模版方法模式定义： 核心思想是在抽象类的一个方法中定义某些“标准”算法。在这个方法中调用的基本操做应由子类重载来实现。这个方法能够被称为所谓的“模板”，它定义方法实现中缺乏了一些针对性的操做。

第一点：定义一个操做中的算法框架 第二点：将一些步骤延时到子类实现 第三点：子类能够不改变算法结构，能够从新定义算法的某些特定步骤

二、模版方法模式应用场景 场景一：多个子类有公有方法，且逻辑基本相同 场景二：重复、复杂的算法，将核心算法设计为模版方法，其周边细节能够由各个子类实现 场景三：代码重载

 使用模板方法要思考如下几点：

1.在父类中一次性实现算法中的不可变部分，并将可变的行为留给子类来实现。

2.子类共用的行为应该被提出来放到公共类中， 以免代码重复。

3.要考虑一些特殊状况特殊处理。这里采用子类的扩展来实现。能够定义一些在特定点调用“钩子”操做方法。子类能够经过对钩子操做的实现从而在这些点上扩展功能。钩子操做默认状况是不对整个模板形成影响的。子类重载后，才为模板算法提供附加的操做。

cocoa Touch框架中使用模板方法

• UIView的定制绘图 drawRect
• UIViewController 让用户处理设备不一样方向的方法,生命周期等

案例分析

模版方法模式->角色划分 两个角色 角色一：抽象类->做用（定义算法框架结构，将一些特定步骤延时到子类实现） 角色二：具体模版实现类，不改变算法结构，选择性去实现某些特定步骤。

三明治制做流程OC：

模板类：

[@interface](https://my.oschina.net/u/996807) AnySandwich : NSObject 
{

}

- (void) make;

// Steps to make a sandwich
- (void) prepareBread;
- (void) putBreadOnPlate;
- (void) addMeat;
- (void) addCondiments;
- (void) extraStep;
- (void) serve;

[@end](https://my.oschina.net/u/567204)

@implementation AnySandwich

- (void) make
{
  [self prepareBread];
  [self putBreadOnPlate];
  [self addMeat];
  [self addCondiments];
  [self extraStep];
  [self serve];
}

- (void) putBreadOnPlate
{
  // We need first to put bread on a plate for any sandwich.
	NSLog(@"放盘");
}

- (void) serve
{
  // Any sandwich will be served eventually.
	NSLog(@"服务");
}

#pragma mark -
#pragma Details will be handled by subclasses

- (void) prepareBread
{
  [NSException raise:NSInternalInconsistencyException
              format:@"You must override %@ in a subclass", NSStringFromSelector(_cmd)];
}

- (void) addMeat
{
  [NSException raise:NSInternalInconsistencyException
              format:@"You must override %@ in a subclass", NSStringFromSelector(_cmd)];
}

- (void) addCondiments
{
  [NSException raise:NSInternalInconsistencyException
              format:@"You must override %@ in a subclass", NSStringFromSelector(_cmd)];
}

- (void) extraStep{}

@end

汉堡类：

#import "AnySandwich.h"

@interface Hamburger : AnySandwich 
{

}

- (void) prepareBread;
- (void) addMeat;
- (void) addCondiments;
//- (void) extraStep;

// Hamburger specific methods
- (void) getBurgerBun;
- (void) addKetchup;
- (void) addMustard;
- (void) addBeefPatty;
- (void) addCheese;
- (void) addPickles;

@end

@implementation Hamburger

- (void) prepareBread;
{
  [self getBurgerBun];
}

- (void) addMeat
{
  [self addBeefPatty];
}

- (void) addCondiments
{
  [self addKetchup];
  [self addMustard];
  [self addCheese];
  [self addPickles];
}

#pragma mark -
#pragma mark Hamburger Specific Methods

- (void) getBurgerBun
{
  // A hamburger needs a bun.
	NSLog(@"添加小圆面包");
}

- (void) addKetchup
{
	NSLog(@"添加番茄酱");
  // Before adding anything to a bun, we need to put ketchup.
}

- (void) addMustard
{
	NSLog(@"添加芥末");
  // Then add some mustard.
}

- (void) addBeefPatty
{
	NSLog(@"添加牛肉");
  // A piece of beef patty is the main character in a burger.
}

- (void) addCheese
{
	NSLog(@"添加起司");
  // Let's just assume every burger has cheese.
}

- (void) addPickles
{
	NSLog(@"添加咸菜");
  // Then finally add some pickles to it.
}

@end

热狗类：

#import "AnySandwich.h"

@interface Hotdog : AnySandwich 
{
  
}

- (void) prepareBread;
- (void) addMeat;
- (void) addCondiments;
//- (void) extraStep;

// Hotdog specific methods
- (void) getHotdogBun;
- (void) addWiener;
- (void) addKetchup;
- (void) addMustard;
- (void) addOnion;

@end

@implementation Hotdog

- (void) prepareBread
{
  [self getHotdogBun];
}

- (void) addMeat
{
  [self addWiener];
}

- (void) addCondiments
{
  [self addKetchup];
  [self addMustard];
  [self addOnion];
}

#pragma mark -
#pragma mark Hotdog Specific Methods

- (void) getHotdogBun
{
  // First of all, we need a hotdog bun.
}

- (void) addWiener
{
  // A nice piece of wiener is the main character here.
}

- (void) addKetchup
{
  // Every hotdog needs ketchup.
}

- (void) addMustard
{
  // I think mustard is also needed.
}

- (void) addOnion
{
  // I think adding onion is a good idea.
}

@end

电脑流水线swift模板类：

class ConmentComputerLine: NSObject {
	final func makeComputer(){
		System()
		DisPlay()
		Memory()
		MainBoard()
		Screen()
		Power()
		Hook()
	}
	
	func System(){
		print("系统")
	}
	func DisPlay(){
		print("显卡")
	}
	func Memory(){
		print("内存")
	}
	func MainBoard(){
		print("主板")
	}
	func Power(){
		print("电源")
	}
	func Screen(){
		print("显示器")
	}
	//钩子 给子类添加额外操做
	func Hook(){}

}

MacComputer:

class MacComputer: ConmentComputerLine {
	
	override func System() {
		print("MAC OS")
	}
	
	override func Hook() {
		TouchBoard()
	}
	func TouchBoard(){
		print("触摸板")
	}
}

WindowsComputer:

class WindowsComputer: ConmentComputerLine {
	override func System() {
		print("Windows2000 OS")
	}
	
	override func Hook() {
		Mouse()
		keyBoard()
	}

	
	func mouse(){
		print("鼠标")
	}
	
	func keyBoard(){
		print("键盘")
	}
}