ios 设计模式备忘录(1)

适用场景：用来进行实现缓存 或 进行一些状态恢复撤销的功能

1.创建管理中心 实现了具体的存储方法

代码.h文件

#import <Foundation/Foundation.h>

#import "MenmentoCenterProtocol.h"

@interface MementoCenter : NSObject

+(void)saveMementoObject:(id<MenmentoCenterProtocol>)object withKey:(NSString *)key;

+(id)mementoObjectWithKey:(NSString *)key;

.m文件

#import "MementoCenter.h"

@implementation MementoCenter

+(void)saveMementoObject:(id)object withKey:(NSString *)key

{

    NSParameterAssert(object);

    NSParameterAssert(key);

    id data=[object currentState];

    [[NSUserDefaults standardUserDefaults] setObject:data forKey:key];

}

+(id)mementoObjectWithKey:(NSString *)key

{

    NSParameterAssert(key);

     id caheData=[[NSUserDefaults standardUserDefaults] objectForKey:key];

    return caheData;

}

@end

2.写协议文件 用来提高可读性 和代码维护 协议里具体标注了 要实现缓存的具体的类需要实现的方法

#import <Foundation/Foundation.h>

//统一存储规范  fastCoder

@protocol MenmentoCenterProtocol <NSObject>

@required

-(id)currentState;

-(void)recoverFromState:(id)state;

@end

.m文件

#import <Foundation/Foundation.h>

#import "MementoCenter.h"

@interface NSObject (MementCenter)

-(void)saveStateWithKey:(NSString *)key;

-(void)recoverStateWithKey:(NSString *)key;

@end

3.在具体需要实现缓存的类中实现 协议的方法

#import "Apple.h"

@implementation Apple

-(id)currentState

{

    return @{@"name":self.name,@"age":self.age};

}

-(void)recoverFromState:(id)state

{

    NSDictionary *data=state;

    self.name=data[@"name"];

    self.age=data[@"age"];

}

4.为了方便 创建个对象的父类的 类别 categoey

导入你的缓存中心

#import <Foundation/Foundation.h>

#import "MementoCenter.h"

@interface NSObject (MementCenter)

-(void)saveStateWithKey:(NSString *)key;

-(void)recoverStateWithKey:(NSString *)key;

#import "NSObject+MementCenter.h"

@implementation NSObject (MementCenter)

-(void)saveStateWithKey:(NSString *)key

{

    id<MenmentoCenterProtocol> obj=(id<MenmentoCenterProtocol>)self;

    if ([obj respondsToSelector:@selector(currentState)]) {

        [MementoCenter saveMementoObject:obj withKey:key];

    }

}

-(void)recoverStateWithKey:(NSString *)key

{

   id state= [MementoCenter mementoObjectWithKey:key];

    id obj=(id<MenmentoCenterProtocol>) self;

    if ([obj respondsToSelector:@selector(recoverFromState:)]) {

        [obj recoverFromState:state];

    }

}

最后就可以使用了