OC中的方法调用，其实都是转换为objc_msgSend函数的调用
objc_msgSend的执行流程可以分为3大阶段
消息发送
动态方法解析
消息转发
///
+（BOOL）resolveInstanceMethod:(SEL)sel
{
If(sel == @selector(test)){
Method method = class_getInstanceMethod(self,@selector(other));
class_addMethod(self,sel,method_getImplementation(method),
method_getTypeEncoding(method));
return YES；
}
return [super resolveInstanceMethod:sel];
}
Void other(id self, SEL _cmd)
{
NSLog(@“%@-%s-%s”,self,sel_getName(_cmd),__func__);
}
+(BOOL)resolveInstanceMethod:(SEL)sel
{
If(sel == @selector(test)){
class_addMethod(Self,sel,(IMP)other,@“v@:”);
return YES；
}
return [super resolveInstanceMethod:sel];
}
///
Method 可以理解为等价于struct method_t*
生成NSMethodSignature
NSMethodSignature * signature = [NSMethodSignature signatureWithObjCTypes : “i@:i”];
NSMethodSignature * signature = [[[MJStudent alloc] init] methodSignatureForSelector:@selector(test:)];
