cocos2d裏面如何實現MVC（五）

更新Model

當用戶從工具箱中選一個小工具，然後把它放置到game board上面去時，我們需要編碼響應這些事件。在上一篇文章中，我們已經實現了GameBoardViewDelegate的touchedAtRow方法。我們還需要給這個協議再添加一個接口方法。如下所示：

@protocol GameBoardViewDelegate
 
- (void)gameBoard:(GameBoard *)gameBoard touchedAtRow:(int)row column:(int)column;
- (void)gameBoard:(GameBoard *)gameBoard toolboxItemTouchedAtIndex:(int)index;
 
@end

 

我們需要修改touch事件處理器，這樣就可以判斷我們到底是觸摸了工具箱還是game board。

- (void)ccTouchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];
    CGPoint point = [self convertTouchToNodeSpace:touch];
 
    // touched on a game board
    if (CGRectContainsPoint(gameBoardRectangle, point)) {
        int row, column;
        // calculate row and column based on a touch coordinate
        // ...
        // call controller
        [self.delegate gameBoard:self.gameBoard touchedAtRow:row column:column];
    }
    // touched on a toolbox
    else if (CGRectContainsPoint(toolboxRectangle, point)) {
        int index;
        // calculate toolbox item index based on a touch coordinate
        [self.delegate gameBoard:self.gameBoard toolboxItemTouchedAtIndex:index];
    }
}

 

在controller類裏面處理touch事件是非常簡單的，我們只需要持有一個model的引用，然後基於touch事件來調用model的方法就行了。我們的接口看起來和下面差不多，只是省略掉了一些實現細節：

@interface GameBoard : NSObject {
// ...
}
 
// ...
- (void)putGamePiece:(GamePiece *)gamePiece row:(int)row column:(int)column;
- (GamePiece *)getGamePieceFromToolboxItemAtIndex:(int)index;
@end

 

然後，我們在GameBoardController裏面完全實現GameBoardViewDelegate的兩個方法。

- (void)gameBoard:(GameBoard *)aGameBoard toolboxItemTouchedAtIndex:(int)index {
    // keep the toolbox selection state in the Model
    gameBoard.selectedToolboxItemIndex = index;
}
 
- (void)gameBoard:(GameBoard *)aGameBoard touchedAtRow:(int)row column:(int)column {
    // if the toolbox item is selected move item from toolbox to game board
    if (gameBoard.selectedToolboxItemIndex != -1) {
        GamePiece *gamePiece = [gameBoard getGamePieceFromToolboxItemAtIndex:gameBoard.selectedToolboxItemIndex];
        [gameBoard putGamePiece:gamePiece row:row column:column];
    }
}

 

到目前爲止，我們實現了，用戶可以點擊工具箱中的小工具，然後把它們放置到game board中的一個小方塊上面，同時model類在中間起了橋樑作用。

通知view關於model的改變

爲了在view裏面反映出model的狀態更改，我們可以在model有變化的時候給view發送通知消息，然後view就可以根據不同的消息來作出不同的響應了。和我們在實現view通過controller一樣，這裏我們也定義了一個GameBoardDelegate，用來通知view model的變化。

@protocol GameBoardDelegate;
@interface GameBoard : NSObject
// ...
@property (nonatomic, assign)
id<GameBoardDelegate> delegate;
// ...
@end
 
@protocol GameBoardDelegate
- (void)gameBoard:(GameBoard *)gameBoard didPutGamePiece:(GamePiece *)gamePiece row:(int)row column:(int)column;
@end
 
@implementation GameBoard
 
- (void)putGamePiece:(GamePiece *)gamePiece row:(int)row column:(int)column {
    // ...
    // store game piece
    // notify that the game piece was put on a gameboard
    [delegate gameBoard:self didPutGamePiece:gamePiece row:row column:column];
}
 
@end

 

在GameBoardView裏面實現GameBoardDelegate的時候，當我們需要在game board上面放置一個小工具的時候，我們定義了一個CCSprite。

@interface GameBoardView : CCLayer
// ...
@end
 
@implementation GameBoardView
 
- (id)initWithGameBoard:(GameBoard *)aGameBoard delegate:(id)aDelegate {
    if ((self = [super init])) {
        // retain gameboard
        self.gameBoard = aGameBoard;
        self.gameBoard.delegate = self;
 
        // assign delegate
        self.delegate = aDelegate;
    }
}
 
- (void)gameBoard:(GameBoard *)gameBoard didPutGamePiece:(GamePiece *)gamePiece row:(int)row column:(int)column {
    // create CCSprite and put it on a game board at corresponding position
    CCSprite *gamePieceSprite = [CCSprite spriteWithFile:fileName];
    // ...
    [self addChild:gamePieceSprite];
}
 
@end

 

總結

現在框架中所有的部分都聯繫起來了，model、view和controller三者組成了著名的MVC模式

• View接收touch事件，然後把事件傳遞給controller,
• Controller 響應用戶的touch事件，然後更新model
• model 更新它自身的狀態, 處理遊戲邏輯，然後告訴view它改變了哪些東西。
• View則基於Model當前的狀態來更新自己的顯示

轉自：http://www.cnblogs.com/andyque/archive/2012/03/18/2390106.html