//

//  ViewController.m

//  ObserverTrampoline

//

//  Created by Rob Napier on 9/7/11.

//  Copyright (c) 2011 __MyCompanyName__. All rights reserved.

//

#import "ViewController.h"

#import "RNObserverManager.h"

@protocol MyProtocol <NSObject>

@optional

- (void)doSomething;

- (void)dodo;

@end

@interface MyClass : NSObject <MyProtocol>

@end

@implementation MyClass

- (void)doSomething {

  NSLog(@"doSomething :%@", self);

}

@end

@interface MyClass1 : NSObject

@end

@implementation MyClass1

- (void)dodo1 {

    NSLog(@"dodo1 :%@", self);

}

- (void)dodo {

    NSLog(@"dodo 要走");

}

@end

@implementation ViewController

//@synthesize observerManager=trampoline_;

- (void)viewDidLoad {

  [super viewDidLoad];

  //这样就可以执行一些事情，比如一个类遵守某个协议，它可以直接调这个协议执行那个类里面写的something

  NSSet *observers = [NSSet setWithObjects:[MyClass new],[MyClass1 new], nil];

  self.observerManager = [[RNObserverManager alloc]

                          initWithProtocol:@protocol(MyProtocol)

                          observers:observers];

  [self.observerManager doSomething];

  [self.observerManager dodo];

}

@end

#import "RNObserverManager.h"

@interface RNObserverManager ()

@property (nonatomic, readonly, strong) NSMutableSet *observers;

@property (nonatomic, readonly, strong) Protocol *protocol;

@end

@implementation RNObserverManager

//协议 集合

- (id)initWithProtocol:(Protocol *)protocol

             observers:(NSSet *)observers {

    if ((self = [super init])) {

        _protocol = protocol;

        _observers = [NSMutableSet setWithSet:observers];

    }

    return self;

}

- (void)addObserver:(id)observer {

  NSAssert([observer conformsToProtocol:self.protocol],

           @"Observer must conform to protocol.");

    [self.observers addObject:observer];

}

- (void)removeObserver:(id)observer {

    [self.observers removeObject:observer];

}

//NSObject --------

//这个函数让重载方有机会抛出一个函数的签名，再由后面的forwardInvocation:去执行。

- (NSMethodSignature *)methodSignatureForSelector:(SEL)sel {

    NSMethodSignature *

  result = [super methodSignatureForSelector:sel];

  if (result) {

   return result;

  }

  // Look for a required method

    struct objc_method_description desc =

             protocol_getMethodDescription(self.protocol,

                                           sel, YES, YES);

    if (desc.name == NULL) {

        // Couldn't find it. Maybe it's optional

        desc = protocol_getMethodDescription(self.protocol,

                                         sel, NO, YES);

    }

    if (desc.name == NULL) {

    // Couldn't find it. Raise NSInvalidArgumentException

        [self doesNotRecognizeSelector:sel];

        return nil;

  }

  return [NSMethodSignature signatureWithObjCTypes:desc.types];

}

//真正执行从methodSignatureForSelector:返回的NSMethodSignature。在这个函数里可以将NSInvocation多次转发到多个对象中，这也是这种方式灵活的地方。（forwardingTargetForSelector只能以Selector的形式转向一个对象）

- (void)forwardInvocation:(NSInvocation *)invocation {

    SEL selector = [invocation selector];

    for (id responder in self.observers) {

        if ([responder respondsToSelector:selector]) {

            [invocation setTarget:responder];

            [invocation invoke];

        }

    }

}