SpriteKit-创建一个计时器

    @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];
    }
}

#1 楼

在Sprite Kit中不要使用NSTimer，performSelector:afterDelay:或Grand Central Dispatch（GCD，即任何dispatch_...方法），因为这些计时方法会忽略节点，场景或视图的paused状态。而且，您不知道它们在游戏循环中的哪一点执行，这可能会导致各种问题，具体取决于您的代码实际执行的操作。

仅有的两种批准的方式可以在基于时间的情况下执行某些操作Sprite Kit是使用SKScene update:方法并使用传入的currentTime参数来跟踪时间。或更常见的是，您只使用以等待动作开始的动作序列：

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，您也可以使用performSelector:onTarget:代替runBlock:或如果需要模仿SKScene customActionWithDuration:actionBlock:方法并且不知道如何将其转发到节点或转发不便的地方，则可以使用update:。

有关详细信息，请参阅SKAction参考。


更新：使用Swift的代码示例

Swift 5

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

Swift 3

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

Swift 2

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

并重复运行代码：

runAction(SKAction.repeatActionForever(SKAction.sequence([wait, run])))

#2 楼

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])))

#3 楼

我以上面的示例为例，并为时钟添加了前导零。

    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])))
}

#4 楼

这是使用Xcode 9.3和Swift 4.1为SpriteKit构建计时器的完整代码。




在我们的示例中，分数标签将每2递增1秒。
这是最终结果


好，我们开始吧！

1）得分标签

首先我们需要一个标签

class GameScene: SKScene {
    private let label = SKLabelNode(text: "Score: 0")
}

2）得分标签进入场景

class GameScene: SKScene {

    private let label = SKLabelNode(text: "Score: 0")

    override func didMove(to view: SKView) {
        self.label.fontSize = 60
        self.addChild(label)
    }
}

现在标签位于屏幕的中心。让我们运行项目来查看它。




请注意，此时标签尚未更新！


3）计数器

我们还想构建一个计数器属性，该属性将保存标签显示的当前值。我们还希望标签属性一旦更改就可以立即更新，以便...

class GameScene: SKScene {

    private let label = SKLabelNode(text: "Score: 0")
    private var counter = 0 {
        didSet {
            self.label.text = "Score: \(self.counter)"
        }
    }

    override func didMove(to view: SKView) {
        self.label.fontSize = 60
        self.addChild(label)

        // let's test it!
        self.counter = 123
    }
}

4）操作

最后，我们要构建一个每2秒将增加计数器的动作

class GameScene: SKScene {

    private let label = SKLabelNode(text: "Score: 0")
    private var counter = 0 {
        didSet {
            self.label.text = "Score: \(self.counter)"
        }
    }

    override func didMove(to view: SKView) {
        self.label.fontSize = 60
        self.addChild(label)
        // 1 wait action
        let wait2Seconds = SKAction.wait(forDuration: 2)
        // 2 increment action
        let incrementCounter = SKAction.run { [weak self] in
            self?.counter += 1
        }
        // 3. wait + increment
        let sequence = SKAction.sequence([wait2Seconds, incrementCounter])
        // 4. (wait + increment) forever
        let repeatForever = SKAction.repeatForever(sequence)

        // run it!
        self.run(repeatForever)
    }
}

#5 楼

以下代码创建一个新线程，并等待2秒，然后对主线程执行操作：

BOOL continueIncrementingScore = YES;

dispatch_async(dispatch_queue_create("timer", NULL);, ^{
    while(continueIncrementingScore) {
        [NSThread sleepForTimeInterval:2];
        dispatch_async(dispatch_get_main_queue(), ^{
            // this is performed on the main thread - increment score here

        });
    }
});

无论何时要停止它，只需将continueIncrementingScore设置为NO