第16月第8天 NSInvocation存储 函数指针 va_arg lldb

1.NSInvocation存储

-(void)setInvok:(id)target sel:(SEL)sel key:(id)key
{
    if(!target) return;
    NSMethodSignature *sig=[target methodSignatureForSelector:sel];
    NSInvocation *invo=[NSInvocation invocationWithMethodSignature:sig];
    [invo setTarget:target];
    [invo setSelector:sel];
    
    NSDictionary *dict = [self currentStyleDict];
    [dict setValue:invo forKey:key];//以key的形式保存invo
}

-(NSInvocation*)selectInvok:(NSString *)key style:(PALiveStyle)style
{
    NSDictionary *dict = [self getStyleDict:style];
    return [dict valueForKey:key];
}

http://blog.sina.com.cn/s/blog_4beb28f30100qask.html

2.函数指针

//常规写法
switch ( oper ){
    case ADD:
        result = add( oper1, oper2 );
        break;
    case SUB:
        result = sub( oper1, oper2 );
        break;
    case MUL:
        result = mul( oper1, oper2 );
        break;
    case DIV:
        result = div( oper1, oper2 );
        break;
    ...
}
//使用转移表之后的写法
double add( double, double );
double sub( double, double );
double mul( double, double );
double div( double, double );
...
double (*oper_func[])( double, double ) = {
    add, sub, mul, div, ...
};
//下面的语句替换前面整条switch语句
result = oper_func[ oper ]( op1, op2 );

https://segmentfault.com/a/1190000000578532

3.runtime

http://justsee.iteye.com/blog/2163777

 4.调用是arg后记得传nil

- (bool)startPlayingStream:(NSString *)streamID inView:(UIView*)view
{
//    NSInvocation *invo=[[MessageInvok shareInvok] selectInvok:@"start_playing_stream" style:PALiveStyleNormal];
//    if(invo)
//    {
////        [data retain];
//        [invo setArgument:&streamID atIndex:2];  //设置参数
//        [invo setArgument:&view atIndex:3];  //设置参数
//        [invo invoke];   //调用
//    }
//    [self invokeMethod:@"start_playing_stream" style:PALiveStyleNormal,streamID,view];
    [self invokeMethod:@"start_playing_stream" style:PALiveStyleNormal arg:streamID,view, nil];

    return true;
}

- (bool)stopPlayingStream:(NSString *)streamID
{
    
    return true;
}

-(NSInvocation *)invokeMethod:(NSString *)method style:(PALiveStyle)style arg:(id)arg, ...
{
    NSMutableArray *arrayList = [NSMutableArray array];
    
    id eachItem;
    va_list argumentList;
    if (arg)
    {
        [arrayList addObject: arg];
        va_start(argumentList, arg);
        while((eachItem = va_arg(argumentList, id)))
        {
            [arrayList addObject: eachItem];
        }
        va_end(argumentList);
    }
    
    NSInvocation *invo=[[MessageInvok shareInvok] selectInvok:@"start_playing_stream" style:style];
    if(invo)
    {
        for (NSUInteger i =0; i<arrayList.count; i++) {
            NSInteger idx = i+2;
            id data = arrayList[i];
            [invo setArgument:&data atIndex:idx];
        }
        
        [invo invoke];   //调用
    }
    
    return invo;
}

 5.lldb e

e aView.backgroundColor = [UIColor greenColor];

 

http://yulingtianxia.com/blog/2015/11/13/Summary-of-the-first-month-in-the-internship-of-Tencent/

https://github.com/opensource-apple/objc4/blob/master/runtime/Messengers.subproj/objc-msg-x86_64.s