ios - 修改正在运行的 SKAction 的速度

Question

我有这个代码:

@implementation MyScene {
SKAction *delayAction; 
}
Inside a method:

delayAction = [SKAction waitForDuration:3.0];
[self runAction:[SKAction repeatActionForever: [SKAction sequence:
                                                @[delayAction, [SKAction ...]]]]]
                                                  withKey:@"myKey"];

然后我想减少加类时间。 (此方法在更新时调用:)所以我尝试了:

    - (void)updateVelocity
{
    NSLog(@"duration:%f",delayAction.duration);
    delayAction.duration = delayAction.duration - 0.001;
}

我得到:

2014-04-04 11:45:05.781 FlyFish[5409:60b] duration:1.300000
2014-04-04 11:45:05.785 FlyFish[5409:60b] duration:1.299000
2014-04-04 11:45:05.800 FlyFish[5409:60b] duration:1.298000
2014-04-04 11:45:05.816 FlyFish[5409:60b] duration:1.297000

这看起来不错，但我的 [SKAction ...] 仍然在 3 秒后继续重复。

Answer 1

我会用不同的方式来做这件事。像这样的……

- (void)recursiveActionMethod
{
    if (some end condition is met) {
        return;
        // this allows you to stop the repeating action.
    }

    self.duration -= 0.01;
    // store duration in a property

    SKAction *waitAction = [SKAction waitForDuration:self.duration];
    SKAction *theAction = [SKAction doWhatYouWantHere];
    SKAction *recursiveAcion = [SKAction performSelector:@selector(recursiveActionMethod) onTarget:self];

    SKAction *sequence = [SKAction sequence:@[waitAction, theAction, recursiveAction]];
    [self runAction:sequence];
}

这将执行您的操作，然后返回此函数以不同的等待时间再次运行，一次又一次，...

您甚至可以通过设置一些会跳转到 if block 内并停止循环的结束条件来停止序列。