我遇到了 HelloWorldLayer 类更新的问题:在我的 iPad 上构建和运行应用程序时未调用方法.

I'm having an issue with the HelloWorldLayer class' update: method not being called when building and running the applications on my iPad.

不太确定问题是什么，因为 init: 和 accelerometer: didAccelerate: 被按预期调用.

Not really sure what the issue is as init: and accelerometer: didAccelerate: are called as expected.

这里是HelloWorldLayer的实现:

Here is the implementation of HelloWorldLayer:

// Import the interfaces
#import "HelloWorldLayer.h"

// Needed to obtain the Navigation Controller
#import "AppDelegate.h"

const float MaxPlayerAccel = 400.0f;
const float MaxPlayerSpeed = 200.0f;

#pragma mark - HelloWorldLayer

// HelloWorldLayer implementation
@implementation HelloWorldLayer
{
    CGSize _winSize;
    CCSprite *_playerSprite;
    UIAccelerationValue _accelerometerX;
    UIAccelerationValue _accelerometerY;

    float _playerAccelX;
    float _playerAccelY;
    float _playerSpeedX;
    float _playerSpeedY;
}

// Helper class method that creates a Scene with the HelloWorldLayer as the only child.
+(CCScene *) scene
{
        // 'scene' is an autorelease object.
    CCScene *scene = [CCScene node];

    // 'layer' is an autorelease object.
    HelloWorldLayer *layer = [HelloWorldLayer node];

    // add layer as a child to scene
    [scene addChild: layer];

    // return the scene
    return scene;
}

// on "init" you need to initialize your instance

- (id)init
{
    if (self = [super initWithColor:ccc4(94, 63, 107, 255)])
    {
        _winSize = [CCDirector sharedDirector].winSize;

        _playerSprite = [CCSprite spriteWithFile:@"Player-hd.png"];
        _playerSprite.position = ccp(_winSize.width - 50.0f, 50.0f);
        [self addChild:_playerSprite];
        self.accelerometerEnabled = YES;
        NSLog(@"init: method executed");
    }
    return self;
}

- (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration     *)acceleration
{
    const double FilteringFactor = 0.75;

    _accelerometerX = acceleration.x * FilteringFactor + _accelerometerX * (1.0 - FilteringFactor);
    _accelerometerY = acceleration.y * FilteringFactor + _accelerometerY * (1.0 - FilteringFactor);

    if (_accelerometerY > 0.05)
    {
        _playerAccelX = -MaxPlayerAccel;
    }
    else if (_accelerometerY < 0.05)
    {
        _playerAccelX = MaxPlayerAccel;
    }

    if (_playerAccelX < -0.05)
    {
        _playerAccelY = -MaxPlayerAccel;
    }
    else if (_playerAccelX > -0.05)
    {
        _playerAccelY = MaxPlayerAccel;
    }
}

- (void)update:(ccTime)dt
{
    NSLog(@"update: method is being called");
    // 1
    _playerSpeedX += _playerAccelX * dt;
    _playerSpeedY += _playerAccelY * dt;

    // 2
    _playerSpeedX = fmaxf(fminf(_playerSpeedX, MaxPlayerSpeed), - MaxPlayerSpeed);
    _playerSpeedY = fmaxf(fminf(_playerSpeedY, MaxPlayerSpeed), - MaxPlayerSpeed);

    // 3
    float newX = _playerSprite.position.x + _playerSpeedX * dt;
    float newY = _playerSprite.position.y + _playerSpeedY * dt;

    // 4
    newX = MIN(_winSize.width, MAX(newX, 0));
    newY = MIN(_winSize.height, MAX(newY, 0));

    _playerSprite.position = ccp(newX, newY);
}  

@end

推荐答案

您需要在 init 方法中安排更新:

You need to schedule the update in your init method:

[self scheduleUpdate];

另外，碰巧看到您的代码可能存在另一个问题 - 您正在将精灵图像加载为 image-hd.png.在 Cocos2D 中，只需要命名不带 -hd 前缀的文件:image.png，如果屏幕是retina，它会自动选择高清版本.

Also, happened to see another possible issue with your code - you're loading the sprite image as image-hd.png. In Cocos2D, you only need to name the file without the -hd prefix: image.png, and it will automatically select the HD version if the screen is retina.