Swift 日常使用Tip

let array = ["a","b","c","f","a","b","a","c"] 
// 先将数组变换为元组数组
let tuplesArray = array.map{($0,1)}  
// 根据元组数组创建字典,并处理相同键操作(+)
let resultDictionary = Dictionary(tuplesArray, uniquingKeysWith: +)
print(resultDictionary)
// 输出结果["b": 2, "f": 1, "a": 3, "c": 2]

struct Student {
     var name: String
     var age: Int
}
extension Student {
    init(name: String) {
         self.name = name 
         age = 0
      }
}

let s1 = Student(name: "Taylor", age: 22)   // 系统默认提供init
let s2 = Student(name: "Taylor Swift")      // 自定义init

enum DeviceOS {
  case tvOs
  case macOs(version: Int)     // 添加版本描述
  case iOS(phone: String)       // 添加描述
}

let d = DeviceOS.iOS(phone: "iphone5")
let f = DeviceOS.macOs(version: 10)
let g = DeviceOS.tvOS
print("d= \(d), f = \(f), g = \(g)")  // 输出d= iOS("iphone5"), f = macOs(10), g = tvOS

#if swift(>=4.0)
    print("swift版本不低于4.0")
#else
    print("swift 版本低于4.0")
#endif

let input = "this is swift string"
let range = NSMakeRange(0, 12)
let swiftRange = Range(range, in: input)

// 角度 -> 弧度
func degree2radian(_ number: Double) -> Double {
    return number * .pi / 180
}
// 弧度 -> 角度
func radian2degree(_ number: Double) -> Double {
   return number * 180 / .pi
}

let states = ProcessInfo.processInfo.thermalState
    switch states {
    case .critical:
         print("system 要死了,警告你别惹我!")
    case .nominal:
        print("system 正常运行")
    case .serious:
        print("system 很累啦~但还能勉强坚持一阵")
    default:
        print("system 你要注意合理调度哦~")
    }

   let redView = UIView(frame: CGRect(x: 70, y: 80, width: 110, height: 110))  // 若macOS中 则使用NSView
    redView.backgroundColor = .red     // macOS中为redView.layer.backgroundColor
    redView.layer.cornerRadius = 20
    if #available(iOS 11.0, *) {
        redView.layer.maskedCorners = [.layerMinXMinYCorner, .layerMaxXMaxYCorner]
    } else {
        // Fallback on earlier versions
    }
    view.addSubview(redView)

extension Array where Element: Hashable {
    func difference(from other: [Element]) -> [Element] {
        return Array(Set(self).symmetricDifference(Set(other)))
    }
}

let n1 = ["a", "b", "c","d"]
let n2 = ["c", "d", "e"]
let difference = n1.difference(from: n2)
print(difference)   // 输出 ["b", "e", "a"]

#if (arch(i386) || arch(x86_64))
    // 这段代码只会在模拟器中运行
#endif

#if (arch(arm64) || arch(armv7))
    // 这段代码只在真机中运行
#endif