[Swift2.0~3.0系列]OptionSetType使用(
2015-09-20 本文已影响2173人
NinthDay
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 = 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:Int
static 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
v1.autoresizingMask = .FlexibleTopMargin | .FlexibleLeftMargin
而swift2.0使用optionSetType之后,声明方式是使用[]
中添加的方式。
v1.autoresizingMask = [.FlexibleTopMargin,.FlexibleLeftMargin]
3 swift3.0中的用法
请见swiftgg Swift 中的选项集合 一文