不斷重複一個動作

Question

我希望我的行動，以每2秒重複。這是我當前的代碼：

SKSpriteNode *lightnut = [SKSpriteNode spriteNodeWithImageNamed:@"lightnut.png"]; 
    BOOL heads = arc4random_uniform(100) < 50; 
    lightnut.position = (heads)? CGPointMake(257,510) : CGPointMake(50,510); 
    [self addChild: lightnut]; 

    SKAction *moveNodeUp = [SKAction moveByX:0.0 y:-600.0 duration:2.0]; 
    [lightnut runAction: moveNodeUp]; 

我該如何重複一遍又一遍地重複上述代碼中所述的操作？我想精靈開始移動，等待2秒鐘，然後啓動另一個。是否有可能之前的原始精靈已完成移動到下一個點發送另一個精靈？

謝謝！

Answer 1

我建議你使用SKAction生成精靈，因爲行動暫停/恢復適當的時候暫停/恢復場景或視圖。這裏有一個如何做一個例子：

// Declare SKAction that waits 2 seconds 
SKAction *wait = [SKAction waitForDuration:2.0];  

// Declare SKAction block to generate the sprites 
SKAction *createSpriteBlock = [SKAction runBlock:^{ 
    SKSpriteNode *lightnut = [SKSpriteNode spriteNodeWithImageNamed:@"lightnut.png"]; 
    BOOL heads = arc4random_uniform(100) < 50; 
    lightnut.position = (heads)? CGPointMake(257,510) : CGPointMake(50,510); 
    [self addChild: lightnut]; 

    SKAction *moveNodeUp = [SKAction moveByX:0.0 y:-600.0 duration:2.0]; 
    [lightnut runAction: moveNodeUp]; 
}]; 

// Combine the actions 
SKAction *waitThenRunBlock = [SKAction sequence:@[wait,createSpriteBlock]]; 

// Lather, rinse, repeat 
[self runAction:[SKAction repeatActionForever:waitThenRunBlock]];