• How to create a method that takes a generic type value as input, and returns a generic type.
    • Func foo(dump: T.type) -> T
    • How to use it
      • foo(dump: Int.type)
  • What is frame of layer?
    • Like view and its superview
    • A layer’s frame is its frame in it’s superLayer’s coordinate
  • What does the mask property of mask mean?
    • The mask is also a layer
    • Default is nil, and all contents will be drawn
    • When it is not nil, the layer’s contents will only be drawn where the mask’s alpha is not zero
    • In this way you can clip layer by a sublayer(although there will not be a layer there)
  • How to check a value got from json is null
    • Value is NSNull
  • How to change array to set in Swift
    • Set
  • What is the new templates in Xcode playground
    • You can now create a viewController in the playground
  • Can you test view in playground
    • Yes, use the new templates, and show the linked view
  • How to implement shadow in iOS
  • How to make rotate to a view
    • View.layer.transform = CATransform3DRotate(originTranform, CGFloat.pi / 4.0, 0, 0, 1)