When ccluaobjcbridge calls the objective-C method to pass the index array, the invalid key to & #39; next & #39; error debugging is reported.

Ccluaobjcbridge is a "bridge" between cocos2d-x engine and objective-C. laoliu's quick-cocos2d-x is encapsulated in its framework and encapsulated into luaoc class:

luaoc.callStaticMethod = CCLuaObjcBridge.callStaticMethod

The function prototype is as follows:

-- [Call the static method in objective-c @ Param string classname class name @ Param string methodname method name @ Param table ARGs counts] function luaoc. callstaticmethod (classname, methodname, argS) End

Suppose there are the following objective-C static methods:

#import <Foundation/Foundation.h>@interface SdkApi : NSObject+ (void)init:(NSDictionary*)dict;@end

When you try to use the following sequence number call, the error "invalid key to 'Next'" will be reported:

luaoc.callStaticMethod("SdkApi", "init", {"platform", true})

Very strange error. debug it step by step, go to ccluaobjcbridge. Mm, and locate the lua_next line of code:

        if (hasArguments)        {            NSMutableDictionary *dict = [NSMutableDictionary dictionary];            lua_pushnil(L);            while (lua_next(L, -2))            {                NSString *key = [NSString stringWithCString:lua_tostring(L, -2) encoding:NSUTF8StringEncoding];                                switch (lua_type(L, -1))                {                    case LUA_TNUMBER:                        [dict setObject:[NSNumber numberWithFloat:lua_tonumber(L, -1)] forKey:key];                        break;                                            case LUA_TBOOLEAN:                        [dict setObject:[NSNumber numberWithBool:lua_toboolean(L, -1)] forKey:key];                        break;                                            case LUA_TSTRING:                        [dict setObject:[NSString stringWithCString:lua_tostring(L, -1) encoding:NSUTF8StringEncoding]                                 forKey:key];                        break;                                            case LUA_TFUNCTION:                        int functionId = retainLuaFunction(L, -1, NULL);                        [dict setObject:[NSNumber numberWithInt:functionId] forKey:key];                        break;                }                                lua_pop(L, 1);            }                        [invocation setArgument:&dict atIndex:2];            [invocation invoke];        }        else        {            [invocation invoke];        }

After reading the code roughly, I did not find any exceptions. So I checked the official documents and finally found out:

int lua_next (lua_State *L, int index);Pops a key from the stack, and pushes a key–value pair from the table at the given index (the "next" pair after the given key). If there are no more elements in the table, then lua_next returns 0 (and pushes nothing).A typical traversal looks like this:     /* table is in the stack at index ‘t‘ */     lua_pushnil(L);  /* first key */     while (lua_next(L, t) != 0) {       /* uses ‘key‘ (at index -2) and ‘value‘ (at index -1) */       printf("%s - %s\n",              lua_typename(L, lua_type(L, -2)),              lua_typename(L, lua_type(L, -1)));       /* removes ‘value‘; keeps ‘key‘ for next iteration */       lua_pop(L, 1);     }While traversing a table, do not call lua_tolstring directly on a key, unless you know that the key is actually a string. Recall that lua_tolstring may change the value at the given index; this confuses the next call to lua_next.See function next for the caveats of modifying the table during its traversal. 

In general, when traversing a table, unless you know that the key is of the string type, do not perform the lua_tolstring operation on the key directly. This is because the lua_tolstring operation may change the value at the specified index, this obfuscated the next call to lua_next.

In short, lua_tolstring may damage the original structure of the table, so do not perform the lua_tolstring operation on the key during traversal.

Lua_tostring finally calls lua_tolstring, so this is the problem.

To avoid this error, you can solve it without passing the index array, for example:

luaoc.callStaticMethod("SdkApi", "init", {platform = "platform", debug = true})

When ccluaobjcbridge calls the objective-C method to pass the index array, the invalid key to & #39; next & #39; error debugging is reported.