swift开发笔记29

当一个数组中包含多种数据类型时，且需要访问元素（对象）的同一种属性（例如Date），可以定一个协议，让每个元素去遵守和实现协议方法。例如：

protocol DateSortable {

  var date: Date { get }

}

 

  init(landingDate: Date = Date(timeIntervalSinceNow: -31725960)) {

    self.landingDate = landingDate

  }

 

enum WeatherCondition: String {

  case cloudy = "Cloudy"

  case sunny = "Sunny"

  case partlyCloudy = "Partly Cloudy"

  case dustStorm = "Dust Storm"

  

  var emoji: String {

    switch self {

    case .cloudy: return "☁️"

    case .sunny: return "☀️"

    case .partlyCloudy: return "⛅️"

    case .dustStorm: return "🌪"

    }

  }

}

  let titleLabel: UILabel = {

    let label = UILabel()

    label.backgroundColor = UIColor.clear

    label.text = "MARSLINK"

    label.font = AppFont()

    label.textAlignment = .center

    label.textColor = UIColor.white

    return label

  }()// 定义时，直接做基本的初始化

 

//if you want a given view to size itself to its parent view, you should add it to the parent view before calling this method.

label.sizeToFit()

 

  let statusIndicator: CAShapeLayer = {

    let layer = CAShapeLayer()

    layer.strokeColor = UIColor.white.cgColor

    layer.lineWidth = 1

    layer.fillColor = UIColor.black.cgColor

    let size: CGFloat = 8

    let frame = CGRect(x: 0, y: 0, width: size, height: size)

    layer.path = UIBezierPath(roundedRect: frame, cornerRadius: size/2).cgPath

    layer.frame = frame

    return layer

  }()

 

let path = UIBezierPath()// 贝塞尔曲线

    path.move(to: .zero)

    path.addLine(to: CGPoint(x: titleWidth, y: 0))

    path.addLine(to: CGPoint(x: titleWidth, y: bounds.height - borderHeight))

    path.addLine(to: CGPoint(x: bounds.width, y: bounds.height - borderHeight))

    path.addLine(to: CGPoint(x: bounds.width, y: bounds.height))

    path.addLine(to: CGPoint(x: 0, y: bounds.height))

    path.close()

    highlightLayer.path = path.cgPath

 

CATransaction.begin()

    CATransaction.setValue(kCFBooleanTrue, forKey: kCATransactionDisableActions)

    statusIndicator.fillColor = (statusOn ? UIColor.white : UIColor.black).cgColor

    CATransaction.commit()

    DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 0.6) {

      self.updateStatus()

    }

 

statusIndicator.position = CGPoint(x: statusLabel.center.x - 50, y: statusLabel.center.y - 1)// position.For more information about the relationship between the frame, bounds, anchorPointand position properties, see Core Animation Programming Guide.

 

var messages: [Message] = {

    var arr = [Message]()

    arr.append(lewisMessage(text: "Mark, are you receiving me?", interval: -803200))

    arr.append(lewisMessage(text: "I think I left behind some ABBA, might help with the drive 😜", interval: -259200))

    return arr

    }() {

    didSet {// 当属性值发生变化时，触发didSet方法

      delegate?.pathfinderDidUpdateMessages(pathfinder: self)

    }

  }

 

private func delay(time: Double = 1, execute work: @escaping @convention(block) () -> Swift.Void) {

  DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + time) {

    work()

  }

}

 

  fileprivate struct CacheEntry: Hashable {

    let text: String

    let font: UIFont

    let width: CGFloat

    let insets: UIEdgeInsets

    

    fileprivate var hashValue: Int {

      return text.hashValue ^ Int(width) ^ Int(insets.top) ^ Int(insets.left) ^ Int(insets.bottom) ^ Int(insets.right)

    }

private func ==(lhs: TextSize.CacheEntry, rhs: TextSize.CacheEntry) -> Bool {

  return lhs.width == rhs.width && lhs.insets == rhs.insets && lhs.text == rhs.text

}

  public static func size(_ text: String, font: UIFont, width: CGFloat, insets: UIEdgeInsets = UIEdgeInsets.zero) -> CGRect {

    let key = CacheEntry(text: text, font: font, width: width, insets: insets)

    if let hit = cache[key] {

      return hit

    }

    

    let constrainedSize = CGSize(width: width - insets.left - insets.right, height: CGFloat.greatestFiniteMagnitude)

    let attributes = [ NSFontAttributeName: font ]

    let options: NSStringDrawingOptions = [.usesFontLeading, .usesLineFragmentOrigin]

    var bounds = (text as NSString).boundingRect(with: constrainedSize, options: options, attributes: attributes, context: nil)

    bounds.size.width = width

    bounds.size.height = ceil(bounds.height + insets.top + insets.bottom)

    cache[key] = bounds

    return bounds

  }