斯坦福Developing iOS 8 Apps学习笔记（二）

一些storyboard的trick

• @IBDesignable 可以在storyboard中预览代码绘图效果（有点tricky，如果画不出来也是有可能的（绘图依赖某些复杂依赖关系））
• @IBInspectable 让某些变量的设置可以在Storyboard中进行，类似于storyboard中原生的Attribute aspect

Extensions

• 对于新手来说，Extension主要功能在于
  
  • 增加某些辅助功能，辅助函数
• 注意
  
  • 在extension中overwrite是不行的
  • 定义property只能是computed，不能有storage
• 对于大神来说Extension是一种架构的方式，具体可在架构书中学习

Protocols and Delegation

Protocol书写中需要注意的地方

protocol SomeProtocol:(class), InheritedProtocol {    var property:Int {get,set}    func aMethod(arg1:Double, ...) -> SomeType    mutating func change()    init(arg:Type)}

• class表示只有类可以遵守的协议
• property要标明get,set还是get
• 对于在结构体和枚举中使用的协议，如果要修改property，需要标注 mutating

Delegation思想的使用方法

1. Create a delegation protocol(defines what the View wants the Controller to take care of)
2. Create a delegate property in the View whose type is that delegation protocol
3. Use the delegation property in the View to get/do
4. Controller declares that it implements the protocol things it can’t own or control
5. Controllers set self as the delegation of the View

??运算符

expression1 ?? expression2
相当于
if expression1 = nil
return expression2
else
return expression1

Gestures

UIPanGestureRecognizer

• translationInView(view:UIView) -> CGPoint
• velocityInView(view:UIView) -> CGPoint
• setTranslation(translation:CGPoint, inView:UIView)
• state:UIGestureRecognizerState
  
  • .Possible
  • .Recognized(discrete)
  • (continues) .Begin .Changed .Ended
  • .Failed
  • .Cancelled(Phone call in)
• 对于state的处理

switch gesture.state    case .Changed:fallthrough    case .Ended:        let translation = gesture.translationInView(aView)        //update        gesture.setTranslation(CGPointZero,inView:aView)    default:break

UIPinchGestureRecognizer

• var scale:CGFloat
• var velocity:CGFloat{get}

UIRotationGestureRecognizer

• var rotation:CGFloat //in radians
• var velocity:CGFloat{get} //in radians

UISwipeGestureRecognizer

• var direction(set when init):UISwipeGestureRecognizerDirection
• var numberOfTouchesRequired:Int //finger count
• 观察state .Recognized状态

UITapGestureRecognizer

• var numberOfTapsRequired:Int //点击次数 If Double,check out .Ended
• var numberOfTouchesRequired:Int //Finger Count