Question

我有2个类ThisWillWorkLayer和ThisWillWorkScene

ThisWillWorkLayer.m

#import "ThisWillWorkLayer.h"
#import "ThisWillWorkScene.h"


@implementation ThisWillWorkLayer


#define kSwipeScale 0.6

-(void) ccTouchMoved: (UITouch *)touch withEvent: (UIEvent *)event {


    CGPoint touchPoint = [touch locationInView:[touch view]];
    touchPoint = [[CCDirector sharedDirector] convertToGL:touchPoint];

    NSLog(@"Touch at x:%d y:%d",(int)touchPoint.x,(int)touchPoint.y);

    [ThisWillWorkScene rotate:touchPoint];
}


@end

只要进行滑动，就会执行ccTouchMoved功能。我的错误是在函数的最后一行。 [ThisWillWorkScene rotate:touchPoint];它表示旋转功能不存在。但是，如果您查看ThisWillWorkScene类，它似乎就是

ThisWillWorkScene.h

#import "CC3Scene.h"

/** A sample application-specific CC3Scene subclass.*/
@interface ThisWillWorkScene : CC3Scene {
    CGPoint lastPoint;
    CC3Camera* cam;

}

-(void) rotate: (CGPoint) touchPoint;

@end

ThisWillWorkScene.m

@implementation ThisWillWorkScene


#define kSwipeScale 0.6

-(void) rotate: (CGPoint) touchPoint{

    //CC3Camera* cam = self.activeCamera;

    // Get the direction and length of the movement since the last touch move event, in
    // 2D screen coordinates. The 2D rotation axis is perpendicular to this movement.
    CGPoint swipe2d = ccpSub(touchPoint, lastPoint);
    CGPoint axis2d = ccpPerp(swipe2d);

    // Project the 2D axis into a 3D axis by mapping the 2D X & Y screen coords
    // to the camera's rightDirection and upDirection, respectively.
    CC3Vector axis = CC3VectorAdd(CC3VectorScaleUniform(cam.rightDirection, axis2d.x),
                                  CC3VectorScaleUniform(cam.upDirection, axis2d.y));
    GLfloat angle = ccpLength(swipe2d) * kSwipeScale;

    // Rotate the cube under direct finger control, by directly rotating by the angle
    // and axis determined by the swipe. If the die cube is just to be directly controlled
    // by finger movement, and is not to freewheel, this is all we have to do.
    CC3MeshNode* helloTxt = (CC3MeshNode*)[self getNodeNamed: @"Hello"];
    [helloTxt rotateByAngle: angle aroundAxis: axis];

    lastPoint = touchPoint;

}


@end

所以我的问题是从ThisWillWorkLayer中调用旋转函数的正确方法是什么

Answer 1

您的rotate:方法是实例方法，而不是类方法。要调用实例方法，您需要有一个该对象的实例来调用它。

例如，此代码适用于您当前的设置：

ThisWillWorkScene *scene = [[ThisWillWorkScene alloc] init]; //Get an instance, you might have to change this
[scene rotate: touchPoint];

如果您希望能够在对象上调用类方法（我认为这不是您想要做的），那么您将更改

-(void) rotate: (CGPoint) touchPoint;

到

+(void) rotate: (CGPoint) touchPoint;

Answer 2

该方法被声明为实例方法。您需要在ThisWillWorkScene的实例上调用它。

如果您不需要将其设为实例方法，则将其声明为类方法。

//in .h
+(void) rotate: (CGPoint) touchPoint;// Notice the plus

//in .m
+(void) rotate: (CGPoint) touchPoint{
    //Code
}

Answer 3

您的[ThisWillWorkScene rotate:touchPoint]正在尝试在ThisWillWorkScene类上调用实例方法。要实现此目的，您的rotate:方法需要使用+作为类方法进行定义，如下所示：

+ (void) rotate ...

根据rotate:方法的内容，它看起来好像是一个类方法。

如果您打算使用ThisWillWorkScene类的实例，那么它将如下所示：

ThisWillWorkScene *scene = [[ThisWillWorkScene] alloc] init];
[scene rotate:touchPoint];

如何从另一个类中的一个类调用函数

3 个答案: