改善系统的通知中心

iOS中的通知中心的实现实现机制是设计模式中的观察者.

在不进行任何修改的情况下,通知中心是这么使用的.

////  NormalViewController.m//  NotificationCenter////  Copyright (c) 2014年 Y.X. All rights reserved.//#import "NormalViewController.h"@interface NormalViewController ()@end@implementation NormalViewController- (void)viewDidLoad{    [super viewDidLoad];    // 注册通知中心    [[NSNotificationCenter defaultCenter] addObserver:self                                             selector:@selector(notificationEvent:)                                                 name:NSStringFromClass([self class])                                               object:nil];        // 发送消息    [[NSNotificationCenter defaultCenter] postNotificationName:NSStringFromClass([self class])                                                        object:nil                                                      userInfo:@{@"name": @"YouXianMing"}];        // 发送消息    [[NSNotificationCenter defaultCenter] postNotificationName:NSStringFromClass([self class])                                                        object:nil                                                      userInfo:@{@"age": @"18"}];}- (void)notificationEvent:(id)sender{    NSNotification *tmp = (NSNotification *)sender;    NSLog(@"%@", tmp.userInfo);}- (void)dealloc{    // 移除通知中心    [[NSNotificationCenter defaultCenter] removeObserver:self                                                    name:NSStringFromClass([self class])                                                  object:nil];}@end

没有对象的概念(都是通过类方法展示):

获取数据部分还有点诡异:

要将其修改到具备对象的概念,且使用起来更加人性化:)以下就是本人对齐进行的修改.

NSObject+NotificationCenter.h   +   NSObject+NotificationCenter.m

////  NSObject+NotificationCenter.h////  http://home.cnblogs.com/u/YouXianMing/////  Copyright (c) 2014年 Y.X. All rights reserved.//#import 
    
     #ifndef SELF_CLASS_NAME #define SELF_CLASS_NAME   [self className]#endif@interface NSObject (NotificationCenter)@property (nonatomic, strong) NSString   *notificationName;  // 通知中心名字// 发送通知消息- (void)sendMessage:(NSDictionary *)obj toName:(NSString *)name;// 注册通知中心- (void)registerNotificationName:(NSString *)name selector:(SEL)selector;// 移除通知中心- (void)removeNotification:(NSString *)name;// 发送消息的对象- (id)messageObject;// 消息名字- (NSString *)messageName;// 当前对象名字+ (NSString *)ClassName;- (NSString *)className;@end
    

////  NSObject+NotificationCenter.m////  http://home.cnblogs.com/u/YouXianMing/////  Copyright (c) 2014年 Y.X. All rights reserved.//#import "NSObject+NotificationCenter.h"#import 
    
     @implementation NSObject (NotificationCenter)/* ================== 扩展了一个属性 ================== */static char notificationNameFlag;- (void)setNotificationName:(NSString *)notificationName{    objc_setAssociatedObject(self, ¬ificationNameFlag,                             nil, OBJC_ASSOCIATION_RETAIN_NONATOMIC);    objc_setAssociatedObject(self, ¬ificationNameFlag,                             notificationName,                             OBJC_ASSOCIATION_RETAIN_NONATOMIC);}- (NSString *)notificationName{    return objc_getAssociatedObject(self, ¬ificationNameFlag);}/* ================== 扩展了一个属性 ================== */- (void)sendMessage:(NSDictionary *)obj toName:(NSString *)name{    // 发送消息    [[NSNotificationCenter defaultCenter] postNotificationName:name                                                        object:nil                                                      userInfo:obj];}- (void)registerNotificationName:(NSString *)name selector:(SEL)selector{    // 如果没有提供名字,则用这个类的名字来注册    if (name == nil)    {        [[NSNotificationCenter defaultCenter] addObserver:self                                                 selector:selector                                                     name:NSStringFromClass([self class])                                                   object:nil];    }    else    {        [[NSNotificationCenter defaultCenter] addObserver:self                                                 selector:selector                                                     name:name                                                   object:nil];    }}- (void)removeNotification:(NSString *)name{    // 如果没有提供名字,则用这个类的名字来移除(注意哦,此处需要与注册处的名字一致!)    if (name == nil)    {        [[NSNotificationCenter defaultCenter] removeObserver:self                                                        name:NSStringFromClass([self class])                                                      object:nil];    }    else    {        [[NSNotificationCenter defaultCenter] removeObserver:self                                                        name:name                                                      object:nil];    }}+ (NSString *)ClassName{    // 返回类名    return NSStringFromClass(self);}- (NSString *)className{    // 返回类名    return NSStringFromClass([self class]);}- (id)messageObject{    // 消息实体内容    if ([self isKindOfClass:[NSNotification class]])    {        NSNotification *tmp = (NSNotification *)self;        return tmp.userInfo;    }    else    {        return nil;    }}- (NSString *)messageName{    // 注册消息者的名字    if ([self isKindOfClass:[NSNotification class]])    {        NSNotification *tmp = (NSNotification *)self;        return tmp.name;    }    else    {        return nil;    }}@end
    

////  RootViewController.m//  NotificationCenter////  Copyright (c) 2014年 Y.X. All rights reserved.//#import "RootViewController.h"#import "NSObject+NotificationCenter.h"@interface RootViewController ()@end@implementation RootViewController- (void)viewDidLoad{    [super viewDidLoad];        // 注册通知中心    [self registerNotificationName:[self className]                          selector:@selector(notificationEvent:)];        // 对象A发送通知    [@"A" sendMessage:@{@"name": @"YouXianMing"}               toName:[self className]];        // 对象B发送通知    [@"B" sendMessage:@{@"age": @"18"}               toName:[self className]];}- (void)notificationEvent:(id)sender{    // 获取到message    id object = [sender messageObject];        // 打印message    NSLog(@"%@", object);}- (void)dealloc{    // 移除注册的通知中心    [self removeNotification:[self className]];}@end

至少,我们减少了认知上面得差异,不需要你知道有通知中心这个东西存在了,取数据也有专门的方法直接获取.

其实,我还扩展了一个NSObject的一个属性,这个属性就是用来标示被注册通知中心名字的,以下展示的是高级用法.

创建Student的Model

////  Student.h//  NotificationCenter////  Copyright (c) 2014年 Y.X. All rights reserved.//#import 
    
     @interface Student : NSObject@property (nonatomic, strong) NSString *name;@end
    

////  Student.m//  NotificationCenter////  Copyright (c) 2014年 Y.X. All rights reserved.//#import "Student.h"#import "NSObject+NotificationCenter.h"@implementation Student@synthesize name = _name;- (void)setName:(NSString *)name{    _name = name;        if (self.notificationName)    {        [self sendMessage:@{@"data": name} toName:self.notificationName];    }}- (NSString *)name{    return _name;}@end

////  RootViewController.m//  NotificationCenter////  Copyright (c) 2014年 Y.X. All rights reserved.//#import "RootViewController.h"#import "NSObject+NotificationCenter.h"#import "Student.h"@interface RootViewController ()@end@implementation RootViewController- (void)viewDidLoad{    [super viewDidLoad];        // 注册通知中心    [self registerNotificationName:[self className]                          selector:@selector(notificationEvent:)];        Student *stu         = [Student new];    stu.notificationName = [self className];    stu.name             = @"YouXianMing";}- (void)notificationEvent:(id)sender{    // 获取到message    id object = [sender messageObject];        // 打印message    NSLog(@"%@", object);}- (void)dealloc{    // 移除注册的通知中心    [self removeNotification:[self className]];}@end