Swift——圖層幾何學（時鐘）

最近在看iOS核心動畫高級技巧，OC語言與Swift轉換有點使人頭疼，某些類和Api改動至關大。因此遇到我很困擾的語法我都會記錄一下，也方便往後回顧。

首先是關於時間的類NSCalendar

這是iOS核心動畫高級技巧——3.圖層幾何學——3.2錨點裏的原文

- (void)tick
{
    //convert time to hours, minutes and seconds
    NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
    NSUInteger units = NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit;
    NSDateComponents *components = [calendar components:units fromDate:[NSDate date]];
    CGFloat hoursAngle = (components.hour / 12.0) * M_PI * 2.0;
    //calculate hour hand angle //calculate minute hand angle
    CGFloat minsAngle = (components.minute / 60.0) * M_PI * 2.0;
    //calculate second hand angle
    CGFloat secsAngle = (components.second / 60.0) * M_PI * 2.0;
    //rotate hands
    self.hourHand.transform = CGAffineTransformMakeRotation(hoursAngle);
    self.minuteHand.transform = CGAffineTransformMakeRotation(minsAngle);
    self.secondHand.transform = CGAffineTransformMakeRotation(secsAngle);
} 
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在我前先後後的各類查找語法糖的狀況下，摸索出三種寫法。

第一種

由於這句代碼NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit 中或的寫法，是在是不知道怎麼轉，因此就暫時沒管它

@objc func tick(){
        
        let calendar = NSCalendar.init(identifier: NSCalendar.Identifier.gregorian)
        
        let hoursAngle = (getComponents(calendar!, unit: .hour) / 12.0) * CGFloat.pi * 2.0
        let minsAngle = (getComponents(calendar!, unit: .minute) / 60.0) * CGFloat.pi * 2.0
        let secsAngle = (getComponents(calendar!, unit: .second) / 60.0) * CGFloat.pi * 2.0
        
        self.hourHand.transform = CGAffineTransform.init(rotationAngle: hoursAngle)
       self.minuteHand.transform = CGAffineTransform.init(rotationAngle: minsAngle)
        self.secondHand.transform = CGAffineTransform.init(rotationAngle: secsAngle)

    }
    
    func getComponents(_ cal:NSCalendar, unit:NSCalendar.Unit) -> CGFloat{
        
        return CGFloat(cal.component(unit, from: Date()))
    }
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第二種

後來老是想着，OC能夠Swift確定也行的，而後發現是這樣寫的

@objc func tick2(){
        
        let calendar = NSCalendar.init(identifier: NSCalendar.Identifier.gregorian)
        
        let units:NSCalendar.Unit = [.hour, .minute, .second]
        
        let comp = calendar!.components(units, from: Date())
        
        setDigit(digit: comp.hour! / 10, forView: self.digitViews[0])
        setDigit(digit: comp.hour! % 10, forView: self.digitViews[1])
        
        setDigit(digit: comp.minute! / 10, forView: self.digitViews[2])
        setDigit(digit: comp.minute! % 10, forView: self.digitViews[3])
        
        setDigit(digit: comp.second! / 10, forView: self.digitViews[4])
        setDigit(digit: comp.second! % 10, forView: self.digitViews[5])
        
    }
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第三種

NS開頭的，Swift確定是會重寫成本身的類的，試試？

@objc func tick3(){
        
        let calendar = Calendar.init(identifier: .gregorian)
        let ccc:Set<Calendar.Component> = [Calendar.Component.hour, Calendar.Component.minute, Calendar.Component.second]
        let comp = calendar.dateComponents(ccc, from: Date())
        
        setDigit(digit: comp.hour! / 10, forView: self.digitViews[0])
        setDigit(digit: comp.hour! % 10, forView: self.digitViews[1])
        
        setDigit(digit: comp.minute! / 10, forView: self.digitViews[2])
        setDigit(digit: comp.minute! % 10, forView: self.digitViews[3])
        
        setDigit(digit: comp.second! / 10, forView: self.digitViews[4])
        setDigit(digit: comp.second! % 10, forView: self.digitViews[5])
        
    }
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這些代碼只是語法的轉換，不是完整代碼。並且代碼量很小，我也不想上傳github，因此直接貼出來，可是沒包括Interface Builder中的佈局，因此我截了張XIB的圖出來。還有不要給約束。

代碼

class ClockController: UIViewController {

    @IBOutlet weak var hourHand: UIImageView!
    
    @IBOutlet weak var minuteHand: UIImageView!
    
    @IBOutlet weak var secondHand: UIImageView!
    
    var timer:Timer!
    
    var timer2:Timer!
    
    @IBOutlet var digitViews:[UIView]!
    
    override func viewDidLoad() {
        super.viewDidLoad()

        self.secondHand.layer.anchorPoint = CGPoint.init(x: 0.5, y: 0.9)
        self.minuteHand.layer.anchorPoint = CGPoint.init(x: 0.5, y: 0.9)
        self.hourHand.layer.anchorPoint = CGPoint.init(x: 0.5, y: 0.9)
        
        timer = Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(tick), userInfo: nil, repeats: true)
        // Do any additional setup after loading the view.
        tick()
        
        setupTick2()
        
    }

    @objc func tick(){
        
        let calendar = NSCalendar.init(identifier: NSCalendar.Identifier.gregorian)
        
        let hoursAngle = (getComponents(calendar!, unit: .hour) / 12.0) * CGFloat.pi * 2.0
        let minsAngle = (getComponents(calendar!, unit: .minute) / 60.0) * CGFloat.pi * 2.0
        let secsAngle = (getComponents(calendar!, unit: .second) / 60.0) * CGFloat.pi * 2.0
        
        self.hourHand.transform = CGAffineTransform.init(rotationAngle: hoursAngle)
       self.minuteHand.transform = CGAffineTransform.init(rotationAngle: minsAngle)
        self.secondHand.transform = CGAffineTransform.init(rotationAngle: secsAngle)

    }
    
    func getComponents(_ cal:NSCalendar, unit:NSCalendar.Unit) -> CGFloat{
        
        return CGFloat(cal.component(unit, from: Date()))
    }

    func setupTick2(){
        
        let digits = UIImage.init(named: "Digits")
        
        for vi in self.digitViews {

            vi.layer.contents = digits?.cgImage
            vi.layer.contentsRect = CGRect.init(x: 0, y: 0, width: 0.1, height: 1.0)
            vi.layer.contentsGravity = kCAGravityResizeAspect
            vi.layer.magnificationFilter = kCAFilterNearest
            
        }
        
        timer2 = Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(tick2), userInfo: nil, repeats: true)
        self.tick2()
    }
    
    @objc func tick2(){
        
        let calendar = NSCalendar.init(identifier: NSCalendar.Identifier.gregorian)
        
        let units:NSCalendar.Unit = [.hour, .minute, .second]
        
        let comp = calendar!.components(units, from: Date())
        
        setDigit(digit: comp.hour! / 10, forView: self.digitViews[0])
        setDigit(digit: comp.hour! % 10, forView: self.digitViews[1])
        
        setDigit(digit: comp.minute! / 10, forView: self.digitViews[2])
        setDigit(digit: comp.minute! % 10, forView: self.digitViews[3])
        
        setDigit(digit: comp.second! / 10, forView: self.digitViews[4])
        setDigit(digit: comp.second! % 10, forView: self.digitViews[5])
        
    }
    
    @objc func tick3(){
        
        let calendar = Calendar.init(identifier: .gregorian)
        let ccc:Set<Calendar.Component> = [Calendar.Component.hour, Calendar.Component.minute, Calendar.Component.second]
        let comp = calendar.dateComponents(ccc, from: Date())
        
        setDigit(digit: comp.hour! / 10, forView: self.digitViews[0])
        setDigit(digit: comp.hour! % 10, forView: self.digitViews[1])
        
        setDigit(digit: comp.minute! / 10, forView: self.digitViews[2])
        setDigit(digit: comp.minute! % 10, forView: self.digitViews[3])
        
        setDigit(digit: comp.second! / 10, forView: self.digitViews[4])
        setDigit(digit: comp.second! % 10, forView: self.digitViews[5])
        
    }
    
    func setDigit(digit:Int, forView view:UIView){
        
        let num = Double(digit)
        view.layer.contentsRect = CGRect.init(x: num * 0.1, y: 0, width: 0.1, height: 1.0)
    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    
}

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