为什么 [SKAction runBlock:^(void){}] 从不工作？

Question

我正在尝试制作无限数量的硬币，这些硬币会一一掉落（waitforduration: 方法制作的空间相等），由于某些原因我无法弄清楚，[NSTread sleepForTimeInterval:] 在sprite kit（第一枚硬币和第二枚硬币之间的差距总是与其他相同的差距不同）所以我尝试使用这段代码，但事实是，它也从来没有用过，我做错了什么？但是我的代码适用于dispatch_queue_t fallingCoinsQueue = dispatch_queue_create("falling coins", nil); dispatch_async(fallingCoinsQueue, ^{ //Do Whatever }); ，但我想使用SKAction runBlock^(void){} 来代替，非常感谢任何帮助。

@interface MyScene()
{
    SKTexture* goldenCoin;
    SKTexture* blackCoin;
}
@property (nonatomic,strong) SKSpriteNode * randomCoinNode;
@end

-(id)initWithSize:(CGSize)size {
    if (self = [super initWithSize:size]) {
        [self AddRightColumnCoins:self.size];
    }
    return self;
}

-(void)AddRightColumnCoins:(CGSize)size{

   __block int counter = 0;

   _randomCoinNode = [SKSpriteNode new];

   SKAction *run = [SKAction runBlock:^(void){

            NSArray * coinArray= [[NSArray alloc] initWithObjects:goldenCoin,blackCoin,nil];
            NSUInteger randomIndex = arc4random() % [coinArray count];
            _randomCoinNode =[SKSpriteNode spriteNodeWithTexture:coinArray[randomIndex]];
            _randomCoinNode.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius: _randomCoinNode.size.width/2];
            CGFloat x = self.view.frame.size.width - ( _randomCoinNode.frame.size.width - 10 );
            CGFloat y = self.view.frame.size.height;
            _randomCoinNode.position = CGPointMake(x , y);
            _randomCoinNode.physicsBody.dynamic = NO;

            if( _randomCoinNode.texture == goldenCoin){
                _randomCoinNode.physicsBody.categoryBitMask = goldenCoinCategory;
            }else{
                _randomCoinNode.physicsBody.categoryBitMask = blackCoinCategory;
            }
            _randomCoinNode.physicsBody.contactTestBitMask = flappyCategory;
            counter++;
            [self addChild: _randomCoinNode];
            _fall = [SKAction moveToY:-50.0f duration:2];
            [_randomCoinNode runAction:_fall];

    }];

    SKAction *wait = [SKAction waitForDuration:0.6];
    SKAction *sequence = [SKAction sequence:@[run, wait]];
    SKAction *repeat = [SKAction repeatActionForever:sequence];
    [_randomCoinNode runAction: repeat];   
}

Answer 1

就个人而言，当涉及到一些事情时，我可能会以不同的方式执行此操作，例如命名硬币纹理，或使用属性与实例变量等。但是，为了保持我的示例，类似于您的代码，这就是您的方式可以做到（复制粘贴看看效果如何）：

#import "GameScene.h"

@interface GameScene()
{
    SKTexture* goldenCoin;
    SKTexture* blackCoin;
}
@end


@implementation GameScene

-(instancetype)initWithSize:(CGSize)size {

    if (self = [super initWithSize:size]) {

        SKTextureAtlas *atlas = [SKTextureAtlas atlasNamed:@"coins"];

        goldenCoin = [atlas textureNamed:@"goldenCoin"];
        blackCoin = [atlas textureNamed:@"blackCoin"];

    }
    return self;
}

-(void)didMoveToView:(SKView *)view{

    //use  withRange: parameter if you want to randomize a delay
    SKAction *wait = [SKAction waitForDuration:1];

    __weak typeof(self) weakSelf = self;

    SKAction *block = [SKAction runBlock:^{

        SKSpriteNode *coin = [weakSelf spawnRandomCoin];
        [weakSelf addChild:coin];
    }];

    SKAction *sequence = [SKAction sequence:@[wait, block]];

    SKAction *loop = [SKAction repeatActionForever:sequence];

    //access this key later to stop spawning
    [self runAction:loop withKey:@"spawning"];
}

-(SKSpriteNode*)spawnRandomCoin {

    NSArray * coinArray= [[NSArray alloc] initWithObjects:goldenCoin,blackCoin,nil];
    NSUInteger randomIndex = arc4random() % [coinArray count];
    NSLog(@"random index : %lu", randomIndex);
    //Create and setup a coin
    SKSpriteNode *coin = [SKSpriteNode spriteNodeWithTexture:coinArray[randomIndex]];

    coin.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius: coin.size.width/2.0f];
    CGFloat x = self.view.frame.size.width - ( coin.frame.size.width - 10.0f );
    CGFloat y = self.view.frame.size.height;
    coin.position = CGPointMake(x , y);
    coin.physicsBody.dynamic = NO;


    //setup coin's category here
    if (coin.texture == blackCoin){

    }else{

    }

    //setup moving action
    SKAction *move = [SKAction moveToY:-coin.size.width duration:5];
    SKAction *moveAndRemove = [SKAction sequence:@[move, [SKAction removeFromParent]]];

    [coin runAction:moveAndRemove withKey:@"moving"];

    return coin;
}
@end

关于您的代码：

• _randomCoinNode，在最好的情况下将存储对添加到场景中的最后一个硬币的引用。这没有多大意义，我想这不是你想要的。

• 在初始化程序、反初始化程序和覆盖的访问器方法（getter 和 setter）之外的任何地方，您都应该使用访问器方法或点语法来访问实例变量（根据文档的建议）。意味着，在你的方法中，你应该使用self.randomCoinNode 而不是_randomCoinNode。

• 我已经在我的 cmets 中提到过其他问题（强引用循环和在块内捕获自我）。