[Swift2.0~3.0系列]OptionSetType使用(更新至3.0) [Swift2.0~3.0系列]OptionSetType使用

1.Option set介绍
swift1.2 设置Option set只需要遵循RawOptionsetType协议即可。早前是这么声明选项集的:

struct Inventory:RawOptionSetType { var rawValue:UInt = 0 init(rawValue:UInt){self.rawValue = https://www.it610.com/article/rawValue} init(nilLiteral:()){rawValue = 0} func toRaw()->UInt{return rawValue} var boolValue:Bool{return rawValue != 0}static func fromRaw(raw:UInt)->Inventory?{return self(rawValue: raw)} static func fromMask(raw:UInt)->Inventory{return self(rawValue: raw)} static var allItems:Inventory{return self(rawValue: 0)} static func convertFromNilLiteral()->Inventory{self(nilLiteral: ())} static var allZeros:Inventory{return self(rawValue: 0)}static var Sword:Inventory{return self(rawValue: 1<<1)} static var Helmet:Inventory{return self(rawValue: 1<<2)} static var Shield:Inventory{return self(rawValue: 1<<3)} }var inventory:Inventory = .Sword | .Shield if inventory & .Shield != nil{ println("has shield") }

卧槽这不是就是或运算吗，确实，经常在设置options时用得比较频繁，而现在的RawOptionsetType协议已经不复存在，取而代之的是OptionSetType,因此可能语法声明和使用上稍有不同，重拾难度。上文代码使用swift2.0改写后是这样的:

struct Inventory:OptionSetType { let rawValue:Intstatic let Sword = Inventory(rawValue: 1) static let Helmet = Inventory(rawValue: 1<<1) static let Shield = Inventory(rawValue: 1<<2) }var inventory:Inventory = [.Sword,.Shield] if inventory.contains(inventory){ print("has shield") }

代码清爽，且提供了许多优秀的方法，比如contains,remove等对集合的操作。
2.实战运用
2.1设置可视化约束时代码改写 swift1.2前，我们经常习惯将options设为nil，但swift2.0中开始报错，修改方法如下

//swift1.2语法 let c1 = NSLayoutConstraint.constraintsWithVisualFormat("H:|-(20)-[v(100)]", options: nil, metrics: nil, views: ["v":v1]) as [NSLayoutConstraint] //swift2.0语法 let c1 = NSLayoutConstraint.constraintsWithVisualFormat("H:|-(20)-[v(100)]", options: [], metrics: nil, views: ["v":v1]) as [NSLayoutConstraint]

2.2设置视图的autoresizingMask swift1.2前，我们习惯使用|来对两个选项进行或运算，如下