//
// 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
实现的方法
#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];
}
}
}
参考：http://www.cnblogs.com/biosli/p/NSObject_inherit_2.html