How to convert a Il2Cpp.Object to a Il2Cpp.ValueType when invoking a method?

[thinhbuzz]

When I try to call Label - a static method I get below error message. So am I doing something wrong? Please help to clarify!

il2cpp: cannot invoke method Label: parameter types mismatch

Code snippet

const unityEngineCoreModule = Il2Cpp.Domain.assembly('UnityEngine.CoreModule').image;
const unityEngineIMGUIModule = Il2Cpp.Domain.assembly('UnityEngine.IMGUIModule').image;
const GUI = unityEngineIMGUIModule.class('UnityEngine.GUI');
const Rect = unityEngineCoreModule.class('UnityEngine.Rect');
const rect = Rect.new();
rect.method('.ctor').overload('System.Single', 'System.Single', 'System.Single', 'System.Single')
  .invoke(200, 200, 300, 220);
const Label = GUI.method('Label').overload(
  'UnityEngine.Rect',
  'System.String',
);
Label.invoke(rect, Il2Cpp.String.from("ahihih aaaa"));

GUI class

// UnityEngine.IMGUIModule
class UnityEngine.GUI : System.Object
{
    static System.Int32 s_ScrollControlId; // 0x0
    static System.Int32 s_HotTextField; // 0x4
    static System.Int32 s_BoxHash; // 0x8
    static System.Int32 s_ButonHash; // 0xc
    static System.Int32 s_RepeatButtonHash; // 0x10
    static System.Int32 s_ToggleHash; // 0x14
    static System.Int32 s_ButtonGridHash; // 0x18
    static System.Int32 s_SliderHash; // 0x1c
    static System.Int32 s_BeginGroupHash; // 0x20
    static System.Int32 s_ScrollviewHash; // 0x24
    static System.Int32 <scrollTroughSide>k__BackingField; // 0x28
    static System.DateTime <nextScrollStepTime>k__BackingField; // 0x30
    static UnityEngine.GUISkin s_Skin; // 0x38
    static UnityEngineInternal.GenericStack <scrollViewStates>k__BackingField; // 0x40
    static UnityEngine.Color get_color(); // 0x04e0aa44
    static System.Void set_color(UnityEngine.Color value); // 0x04e0ab1c
    static System.Void set_changed(System.Boolean value); // 0x04e0abf0
    static System.Boolean get_usePageScrollbars(); // 0x04e0ac30
    static UnityEngine.Material get_blendMaterial(); // 0x04e0ac64
    static UnityEngine.Material get_blitMaterial(); // 0x04e0ac98
    static UnityEngine.Material get_roundedRectMaterial(); // 0x04e0accc
    static UnityEngine.Material get_roundedRectWithColorPerBorderMaterial(); // 0x04e0ad00
    static System.Void GrabMouseControl(System.Int32 id); // 0x04e0ad34
    static System.Boolean HasMouseControl(System.Int32 id); // 0x04e0ad74
    static System.Void ReleaseMouseControl(); // 0x04e0adb4
    static System.Void InternalRepaintEditorWindow(); // 0x04e0ade8
    static UnityEngine.Rect Internal_DoWindow(System.Int32 id, System.Int32 instanceID, UnityEngine.Rect clientRect, UnityEngine.GUI.WindowFunction func, UnityEngine.GUIContent title, UnityEngine.GUIStyle style, System.Object skin, System.Boolean forceRectOnLayout)
; // 0x04e0ae1c
    static System.Void .cctor(); // 0x04e0afb4
    static System.Int32 get_scrollTroughSide(); // 0x04e0b1f0
    static System.Void set_scrollTroughSide(System.Int32 value); // 0x04e0b258
    static System.DateTime get_nextScrollStepTime(); // 0x04e0b2c4
    static System.Void set_nextScrollStepTime(System.DateTime value); // 0x04e0b32c
    static System.Void set_skin(UnityEngine.GUISkin value); // 0x04e0b398
    static UnityEngine.GUISkin get_skin(); // 0x04e0b554
    static System.Void DoSetSkin(UnityEngine.GUISkin newSkin); // 0x04e0b4a4
    static UnityEngine.Matrix4x4 get_matrix(); // 0x04e0b71c
    static System.Void set_matrix(UnityEngine.Matrix4x4 value); // 0x04e0b804
    static System.Void Label(UnityEngine.Rect position, System.String text); // 0x04e0b89c
    static System.Void Label(UnityEngine.Rect position, UnityEngine.GUIContent content, UnityEngine.GUIStyle style); // 0x04e0ba24
    static System.Void DrawTexture(UnityEngine.Rect position, UnityEngine.Texture image); // 0x04e0bc80
    static System.Void DrawTexture(UnityEngine.Rect position, UnityEngine.Texture image, UnityEngine.ScaleMode scaleMode); // 0x04e0bd18
    static System.Void DrawTexture(UnityEngine.Rect position, UnityEngine.Texture image, UnityEngine.ScaleMode scaleMode, System.Boolean alphaBlend); // 0x04e0bdc0
    static System.Void DrawTexture(UnityEngine.Rect position, UnityEngine.Texture image, UnityEngine.ScaleMode scaleMode, System.Boolean alphaBlend, System.Single imageAspect); // 0x04e0be70
    static System.Void DrawTexture(UnityEngine.Rect position, UnityEngine.Texture image, UnityEngine.ScaleMode scaleMode, System.Boolean alphaBlend, System.Single imageAspect, UnityEngine.Color color, System.Single borderWidth, System.Single borderRadius); // 0x04e
0bf4c
    static System.Void DrawTexture(UnityEngine.Rect position, UnityEngine.Texture image, UnityEngine.ScaleMode scaleMode, System.Boolean alphaBlend, System.Single imageAspect, UnityEngine.Color color, UnityEngine.Vector4 borderWidths, System.Single borderRadius); /
/ 0x04e0c080
    static System.Void DrawTexture(UnityEngine.Rect position, UnityEngine.Texture image, UnityEngine.ScaleMode scaleMode, System.Boolean alphaBlend, System.Single imageAspect, UnityEngine.Color color, UnityEngine.Vector4 borderWidths, UnityEngine.Vector4 borderRadi
uses); // 0x04e0c1e0
    static System.Void DrawTexture(UnityEngine.Rect position, UnityEngine.Texture image, UnityEngine.ScaleMode scaleMode, System.Boolean alphaBlend, System.Single imageAspect, UnityEngine.Color color, UnityEngine.Vector4 borderWidths, UnityEngine.Vector4 borderRadi
uses, System.Boolean drawSmoothCorners); // 0x04e0c348
    static System.Void DrawTexture(UnityEngine.Rect position, UnityEngine.Texture image, UnityEngine.ScaleMode scaleMode, System.Boolean alphaBlend, System.Single imageAspect, UnityEngine.Color leftColor, UnityEngine.Color topColor, UnityEngine.Color rightColor, Un
ityEngine.Color bottomColor, UnityEngine.Vector4 borderWidths, UnityEngine.Vector4 borderRadiuses, System.Boolean drawSmoothCorners); // 0x04e0c498
    static System.Boolean CalculateScaledTextureRects(UnityEngine.Rect position, UnityEngine.ScaleMode scaleMode, System.Single imageAspect, UnityEngine.Rect& outScreenRect, UnityEngine.Rect& outSourceRect); // 0x04e0cb24
    static System.Void Box(UnityEngine.Rect position, UnityEngine.GUIContent content, UnityEngine.GUIStyle style); // 0x04e0cd88
    static System.Boolean Button(UnityEngine.Rect position, UnityEngine.GUIContent content); // 0x04e0d018
    static System.Boolean Button(UnityEngine.Rect position, UnityEngine.GUIContent content, UnityEngine.GUIStyle style); // 0x04e0d0cc
    static System.Boolean Button(UnityEngine.Rect position, System.Int32 id, UnityEngine.GUIContent content, UnityEngine.GUIStyle style); // 0x04e0d1fc
    static System.Boolean DoRepeatButton(UnityEngine.Rect position, UnityEngine.GUIContent content, UnityEngine.GUIStyle style, UnityEngine.FocusType focusType); // 0x04e0d3d0
    static System.String PasswordFieldGetStrToShow(System.String password, System.Char maskChar); // 0x04e0d7b4
    static System.Void DoTextField(UnityEngine.Rect position, System.Int32 id, UnityEngine.GUIContent content, System.Boolean multiline, System.Int32 maxLength, UnityEngine.GUIStyle style); // 0x04e0d908
    static System.Void DoTextField(UnityEngine.Rect position, System.Int32 id, UnityEngine.GUIContent content, System.Boolean multiline, System.Int32 maxLength, UnityEngine.GUIStyle style, System.String secureText); // 0x04e0d9d0
    static System.Void DoTextField(UnityEngine.Rect position, System.Int32 id, UnityEngine.GUIContent content, System.Boolean multiline, System.Int32 maxLength, UnityEngine.GUIStyle style, System.String secureText, System.Char maskChar); // 0x04e0daa8
    static System.Void HandleTextFieldEventForTouchscreen(UnityEngine.Rect position, System.Int32 id, UnityEngine.GUIContent content, System.Boolean multiline, System.Int32 maxLength, UnityEngine.GUIStyle style, System.String secureText, System.Char maskChar, Unity
Engine.TextEditor editor); // 0x04e0df70
    static System.Void HandleTextFieldEventForDesktop(UnityEngine.Rect position, System.Int32 id, UnityEngine.GUIContent content, System.Boolean multiline, System.Int32 maxLength, UnityEngine.GUIStyle style, UnityEngine.TextEditor editor); // 0x04e0e3ac
    static System.Boolean DoControl(UnityEngine.Rect position, System.Int32 id, System.Boolean on, System.Boolean hover, UnityEngine.GUIContent content, UnityEngine.GUIStyle style); // 0x04e0f85c
    static System.Void DoLabel(UnityEngine.Rect position, UnityEngine.GUIContent content, UnityEngine.GUIStyle style); // 0x04e0bacc
    static System.Boolean DoButton(UnityEngine.Rect position, System.Int32 id, UnityEngine.GUIContent content, UnityEngine.GUIStyle style); // 0x04e0d2ac
    static System.Single Slider(UnityEngine.Rect position, System.Single value, System.Single size, System.Single start, System.Single end, UnityEngine.GUIStyle slider, UnityEngine.GUIStyle thumb, System.Boolean horiz, System.Int32 id, UnityEngine.GUIStyle thumbExt
ent); // 0x04e0fe64
    static System.Single HorizontalScrollbar(UnityEngine.Rect position, System.Single value, System.Single size, System.Single leftValue, System.Single rightValue, UnityEngine.GUIStyle style); // 0x04e1005c
    static System.Boolean ScrollerRepeatButton(System.Int32 scrollerID, UnityEngine.Rect rect, UnityEngine.GUIStyle style); // 0x04e10c94
    static System.Single VerticalScrollbar(UnityEngine.Rect position, System.Single value, System.Single size, System.Single topValue, System.Single bottomValue, UnityEngine.GUIStyle style); // 0x04e10fd8
    static System.Single Scroller(UnityEngine.Rect position, System.Single value, System.Single size, System.Single leftValue, System.Single rightValue, UnityEngine.GUIStyle slider, UnityEngine.GUIStyle thumb, UnityEngine.GUIStyle leftButton, UnityEngine.GUIStyle r
ightButton, System.Boolean horiz); // 0x04e10590
    static UnityEngineInternal.GenericStack get_scrollViewStates(); // 0x04e1127c
    static UnityEngine.Vector2 BeginScrollView(UnityEngine.Rect position, UnityEngine.Vector2 scrollPosition, UnityEngine.Rect viewRect, System.Boolean alwaysShowHorizontal, System.Boolean alwaysShowVertical, UnityEngine.GUIStyle horizontalScrollbar, UnityEngine.GU
IStyle verticalScrollbar, UnityEngine.GUIStyle background); // 0x04e112e4
    static System.Void EndScrollView(System.Boolean handleScrollWheel); // 0x04e1231c
    static UnityEngine.Rect Window(System.Int32 id, UnityEngine.Rect clientRect, UnityEngine.GUI.WindowFunction func, System.String text, UnityEngine.GUIStyle style); // 0x04e127b0
    static UnityEngine.Rect DoWindow(System.Int32 id, UnityEngine.Rect clientRect, UnityEngine.GUI.WindowFunction func, UnityEngine.GUIContent title, UnityEngine.GUIStyle style, UnityEngine.GUISkin skin, System.Boolean forceRectOnLayout); // 0x04e128ac
    static System.Void CallWindowDelegate(UnityEngine.GUI.WindowFunction func, System.Int32 id, System.Int32 instanceID, UnityEngine.GUISkin _skin, System.Int32 forceRect, System.Single width, System.Single height, UnityEngine.GUIStyle style); // 0x04e12998        
    static System.Void get_color_Injected(UnityEngine.Color& ret); // 0x04e0aadc
    static System.Void set_color_Injected(UnityEngine.Color& value); // 0x04e0abb0
    static System.Void Internal_DoWindow_Injected(System.Int32 id, System.Int32 instanceID, UnityEngine.Rect& clientRect, UnityEngine.GUI.WindowFunction func, UnityEngine.GUIContent title, UnityEngine.GUIStyle style, System.Object skin, System.Boolean forceRectOnLa
yout, UnityEngine.Rect& ret); // 0x04e0af14
}

[vfsfitvnm]

Hi, UnityEngine.Rect is a value type (aka a struct).
This line

const rect = Rect.new();

creates a reference type (aka a object).

So, the method

static System.Void Label(UnityEngine.Rect position, System.String text); // 0x04e0b89c

expects a struct, but you are passing a object.

So, you have to unbox the object first in order to call Label:

Label.invoke(new Il2Cpp.ValueType(rect.unbox(), rect.class.type), Il2Cpp.String.from("ahihih aaaa"));

[thinhbuzz]

@vfsfitvnm
OMG, I see, I think this should be included in the wiki

[vfsfitvnm]

@thinhbuzz
Yeah, the overall documentation is poor and there is a lack of good examples. Unfortunately I do not have the skills / the patience to write a good one, so I just stick with this "let the user open an issue, answer it, move to discussion" cycle lol.

Instead of a wiki (nobody reads boring ass wall of text), it should be something like a codelab