structobjc_class {
Class isaOBJC_ISA_AVAILABILITY;
#if !__OBJC2__
Class super_classOBJC2_UNAVAILABLE;//父类
constchar*nameOBJC2_UNAVAILABLE;//类名
longversionOBJC2_UNAVAILABLE;//版本号，默认0
longinfoOBJC2_UNAVAILABLE;//类信息
longinstance_sizeOBJC2_UNAVAILABLE;//类实例变量大小
structobjc_ivar_list *ivarsOBJC2_UNAVAILABLE;//属性列表
structobjc_method_list **methodListsOBJC2_UNAVAILABLE;//方法列表
structobjc_cache *cacheOBJC2_UNAVAILABLE;//经常调用的方法列表
structobjc_protocol_list *protocolsOBJC2_UNAVAILABLE;//协议列表
#endif
}OBJC2_UNAVAILABLE;
方法
-(void)test
{
//获取属性列表
unsignedintcount;
objc_property_t*propertyList =class_copyPropertyList([selfclass], &count);
for(NSIntegeri =0;i<count;i++)
{
constchar*property =property_getName(propertyList[i]);
NSLog(@"%@",[NSStringstringWithUTF8String:property]);
}
objc_property_tt =class_getProperty([selfclass],"str4");
//获取方法列表
Method*methodList =class_copyMethodList([selfclass], &count);
for(NSIntegeri =0;i<count;i++)
{
Methodmethod = methodList[i];
NSLog(@"%@",NSStringFromSelector(method_getName(method)));
}
//获取成员变量列表
Ivar*ivarList =class_copyIvarList([selfclass], &count);
for(NSIntegeri =0;i<count;i++)
{
Ivarivar = ivarList[i];
NSLog(@"%@",[NSStringstringWithUTF8String:ivar_getName(ivar)]);
}
//获取协议列表
__unsafe_unretainedProtocol **protocolList =class_copyProtocolList([selfclass], &count);
for(NSIntegeri =0;i<count;i++)
{
Ivarivar = ivarList[i];
NSLog(@"%@",[NSStringstringWithUTF8String:ivar_getName(ivar)]);
}
}
方法调用
消息发送过程，objc_msgsend(id,SEL,var...)
首先在对象的类对象的chche，methodList以及父类对象的cache,methondList里寻找SEL对应的IMP
如果没有找到，实现了方法//动态决议方法
+ (BOOL)resolveClassMethod:(SEL)name;
+ (BOOL)resolveInstanceMethod:(SEL)name;
并且在里面提供了相应的SEL，那就能正确运行，否则
跳到//消息转发函数 让别的对象去执行这个函数
- (id)forwardingTargetForSelector:(SEL)aSelector
如果未实现//将目标函数以其他形式执行
- (NSMethodSignature *)methodSignatureForSelector:(SEL)aSelector
- (void)forwardInvocation:(NSInvocation *)anInvocation
否则到
- (void)doesNotRecognizeSelector:(SEL)aSelector
crash
简单例子
voiddynamicMethodIMP(idself,SEL_cmd)
{
printf("SEL %s did not exist\n",sel_getName(_cmd));
}
//动态方法解析 动态加方法
+(BOOL)resolveInstanceMethod:(SEL)sel
{
//if(sel==@selector(some))
//{
//class_addMethod([self class],sel,(IMP)dynamicMethodIMP,"v@:");
//return YES;
//
//}
return[superresolveInstanceMethod:sel];;
}
//转交给其他类处理
-(id)forwardingTargetForSelector:(SEL)aSelector
{
//if(aSelector==@selector(some))
//{
//
//return [ViewController new];
//}
returnnil;
}
//完整消息转发机制
- (NSMethodSignature*)methodSignatureForSelector:(SEL)aSelector {
NSMethodSignature*sig;
sig = [[ViewControllernew]methodSignatureForSelector:aSelector];
returnsig;
}
-(void)forwardInvocation:(NSInvocation*)anInvocation
{
idtarget = [ViewControllernew];
[anInvocationinvokeWithTarget:target];
}
SEL : 类成员方法的指针，但不同于C语言中的函数指针，函数指针直接保存了方法的地址，但SEL只是方法编号。
IMP:一个函数指针,保存了方法的地址
关联对象
NSString*something =@"111";
UILabel*label = [UILabelnew];
objc_setAssociatedObject(something, &someKey, label,OBJC_ASSOCIATION_RETAIN);
UILabel*label1 =objc_getAssociatedObject(something, &someKey);
方法交换 method swizzling
void method_exchangeImplementations(Method m1, Method m2)
//放在load里是因为load只触发一次，用dispatch_once也可以
+(void)load
{
MethodfromMethod =class_getInstanceMethod(self,@selector(viewDidLoad));
MethodtoMethod =class_getInstanceMethod(self,@selector(changeMethod));
if(!class_addMethod([selfclass],@selector(viewDidLoad),method_getImplementation(toMethod),method_getTypeEncoding(toMethod)))
{
method_exchangeImplementations(fromMethod,toMethod);
}
}
//这边[self changeMethod];其实调用的是[self viewDidLoad];
-(void)changeMethod
{
NSLog(@"changeMethod");
[self changeMethod];
}
框架：JRSwizzle
参考http://www.cocoachina.com/ios/20150901/13173.html
