ios - 在另一个对象中初始化 UISwipeGestureRecognizer 时使用未声明的标识符 'action'

Question

我正在尝试在我的 ViewController 的 viewDidLoad 中创建一个 UISwipeGestureRecognizer，它将使用一个选择器来调用另一个对象 (MyScene) 中的一个方法。但是，我收到以下错误:

Use of undeclared identifer 'action'

是否有这不起作用的原因？

示例代码:

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

// Configure the view.
SKView * skView = (SKView *)self.view;
if (!skView.scene) {
  skView.showsFPS = YES;
  skView.showsNodeCount = YES;

  // Create and configure the scene.
  SKScene * scene = [MyScene sceneWithSize:skView.bounds.size];
  scene.scaleMode = SKSceneScaleModeAspectFill;
  // Present the scene.
  [skView presentScene:scene];

    UISwipeGestureRecognizer *swipeRight = [[UISwipeGestureRecognizer alloc] initWithTarget:(MyScene) action:@selector(screenSwipedRight)];
    swipeRight.numberOfTouchesRequired = 1;
    swipeRight.direction=UISwipeGestureRecognizerDirectionRight;
    [self.view addGestureRecognizer:(swipeRight)];

    UISwipeGestureRecognizer *swipeLeft = [[UISwipeGestureRecognizer alloc] initWithTarget:(MyScene) action:@selector(screenSwipedLeft)];
    swipeLeft.numberOfTouchesRequired = 1;
    swipeLeft.direction=UISwipeGestureRecognizerDirectionLeft;
    [self.view addGestureRecognizer:(swipeLeft)];

    UISwipeGestureRecognizer *swipeUp = [[UISwipeGestureRecognizer alloc] initWithTarget:(MyScene) action:@selector(screenSwipedUp)];
    swipeUp.numberOfTouchesRequired = 1;
    swipeUp.direction=UISwipeGestureRecognizerDirectionUp;
    [self.view addGestureRecognizer:(swipeUp)];
    }
}

如果需要更多详细信息，我很乐意提供任何其他信息。

感谢您花时间提供帮助!

Answer 1

目标需要是一个类的实例:

UISwipeGestureRecognizer *swipeRight = [[UISwipeGestureRecognizer alloc] initWithTarget:(MyScene) action:@selector(screenSwipedRight)];

可能需要:

UISwipeGestureRecognizer *swipeRight = [[UISwipeGestureRecognizer alloc] initWithTarget: scene action:@selector(screenSwipedRight)];

Merhod screenSwipedRight 应该是 MyScene 类的公共(public)方法。