类方法的消息转发

+ (void)eat;

#pragma mark 类方法的消息转发
+ (BOOL)resolveClassMethod:(SEL)sel {
    if (sel == @selector(eat)) {
        NSLog(@"+ resolveClassMethod");
        return YES;
    }
    return [super resolveClassMethod:sel];
}
+ (id)forwardingTargetForSelector:(SEL)aSelector {
    if (aSelector == @selector(eat)) {
        NSLog(@"+ forwardingTargetForSelector");
        return nil;
    }
    return [super forwardingTargetForSelector:aSelector];
}
+ (NSMethodSignature *)methodSignatureForSelector:(SEL)aSelector {
    if (aSelector == @selector(eat)) {
        NSLog(@"+ methodSignatureForSelector");
        return [NSMethodSignature signatureWithObjCTypes:"v@:"];
    }
    return [super methodSignatureForSelector:aSelector];
}
+ (void)forwardInvocation:(NSInvocation *)anInvocation {
    NSLog(@"+ forwardInvocation");
    NSLog(@"1 %@", anInvocation.target);
    NSLog(@"2 %s", anInvocation.selector);
}