SpriteKit - 创建一个计时器

Question

我怎样才能创建一个每两秒触发一次的计时器,它会在我屏幕上的HUD上将分数增加一个？这是我对HUD的代码:

    @implementation MyScene
{
    int counter;
    BOOL updateLabel;
    SKLabelNode *counterLabel;
}

-(id)initWithSize:(CGSize)size
{
    if (self = [super initWithSize:size])
    {
        counter = 0;

        updateLabel = false;

        counterLabel = [SKLabelNode labelNodeWithFontNamed:@"Chalkduster"];
        counterLabel.name = @"myCounterLabel";
        counterLabel.text = @"0";
        counterLabel.fontSize = 20;
        counterLabel.fontColor = [SKColor yellowColor];
        counterLabel.horizontalAlignmentMode = SKLabelHorizontalAlignmentModeCenter;
        counterLabel.verticalAlignmentMode = SKLabelVerticalAlignmentModeBottom;
        counterLabel.position = CGPointMake(50,50); // change x,y to location you want
        counterLabel.zPosition = 900;
        [self addChild: counterLabel];
    }
}

Answer 1

在Sprite Kit中不使用 NSTimer,performSelector:afterDelay:或Grand Central Dispatch(GCD,即任何dispatch_...方法),因为这些计时方法忽略节点,场景或视图的paused状态.此外,您不知道它们在游戏循环中的哪个位置执行会导致各种问题,具体取决于您的代码实际执行的操作.

在Sprite Kit中执行基于时间的事情的唯一两种制裁方法是使用SKScene update:方法并使用传入的currentTime参数来跟踪时间.

或者更常见的是,您只需使用以等待操作开头的动作序列:

id wait = [SKAction waitForDuration:2.5];
id run = [SKAction runBlock:^{
    // your code here ...
}];
[node runAction:[SKAction sequence:@[wait, run]]];

并重复运行代码:

[node runAction:[SKAction repeatActionForever:[SKAction sequence:@[wait, run]]]];

或者performSelector:onTarget:,如果您需要模仿SKScene 方法并且不知道如何将其转发到节点或转发不方便的地方,您也可以使用代替runBlock:或可能使用.customActionWithDuration:actionBlock:update:

有关详细信息,请参阅SKAction参考.

更新:使用Swift的代码示例

斯威夫特3

 run(SKAction.repeatForever(SKAction.sequence([
     SKAction.run( /*code block or a func name to call*/ ),
     SKAction.wait(forDuration: 2.5)
     ])))

斯威夫特2

let wait = SKAction.wait(forDuration:2.5)
let action = SKAction.run {
    // your code here ...
}
run(SKAction.sequence([wait,action]))

Aund重复运行代码:

let wait = SKAction.waitForDuration(2.5)
let run = SKAction.runBlock {
    // your code here ...
}
runAction(SKAction.sequence([wait, run]))

Answer 2

在Swift中可用:

var timescore = Int()  
var actionwait = SKAction.waitForDuration(0.5)
            var timesecond = Int()
            var actionrun = SKAction.runBlock({
                    timescore++
                    timesecond++
                    if timesecond == 60 {timesecond = 0}
                    scoreLabel.text = "Score Time: \(timescore/60):\(timesecond)"
                })
            scoreLabel.runAction(SKAction.repeatActionForever(SKAction.sequence([actionwait,actionrun])))

Answer 3

我已经采取了上面的快速示例并添加了时钟的前导零.

    func updateClock() {
    var leadingZero = ""
    var leadingZeroMin = ""
    var timeMin = Int()
    var actionwait = SKAction.waitForDuration(1.0)
    var timesecond = Int()
    var actionrun = SKAction.runBlock({
        timeMin++
        timesecond++
        if timesecond == 60 {timesecond = 0}
        if timeMin  / 60 <= 9 { leadingZeroMin = "0" } else { leadingZeroMin = "" }
        if timesecond <= 9 { leadingZero = "0" } else { leadingZero = "" }

        self.flyTimeText.text = "Flight Time [ \(leadingZeroMin)\(timeMin/60) : \(leadingZero)\(timesecond) ]"
    })
    self.flyTimeText.runAction(SKAction.repeatActionForever(SKAction.sequence([actionwait,actionrun])))
}