ios 枚举大小写的原始值必须是文字
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Raw value for enum case must be a literal
提问by Arbitur
I have this enum:
我有这个枚举：
enum GestureDirection:UInt {
case Up = 1 << 0
case Down = 1 << 1
case Left = 1 << 2
case Right = 1 << 3
}
But on every case I get error:
但在每种情况下，我都会出错：
Raw value for enum case must be a literal
枚举大小写的原始值必须是文字
I dont get it.
我不明白。
Swift 1.2, Xcode 6.3.2
斯威夫特 1.2，Xcode 6.3.2
采纳答案by Benjamin Gruenbaum
That's because 1 << 0isn't a literal. You can use a binary literal which is a literal and is allowed there:
那是因为1 << 0不是文字。您可以使用一个二进制文字，它是一个文字并且在那里被允许：
enum GestureDirection:UInt {
case Up = 0b000
case Down = 0b001
case Left = 0b010
case Right = 0b100
}
Enums only support raw-value-literals which are either numeric-literal(numbers) string-literal-(strings) or boolean-literal-(bool) per the language grammar.
枚举仅支持根据语言语法raw-value-literal为numeric-literal(numbers) string-literal-(strings) 或boolean-literal-(bool) 的s 。
Instead as a workaround and still give a good indication of what you're doing.
相反，作为一种解决方法，仍然可以很好地说明您在做什么。
回答by Martin R
For attributes which are not mutually exclusive I would also recommend to
use a structbased on RawOptionSetTypeas @Vincent suggested.
One advantage is that you get all bit operations for free.
对于不相互排斥的属性，我还建议使用@Vincent 建议的struct基于RawOptionSetType。一个优势是您可以免费获得所有位操作。
Here is a full working example:
这是一个完整的工作示例：
struct GestureDirection : RawOptionSetType {
let rawValue : UInt8
init(rawValue: UInt8) {
self.rawValue = rawValue
}
init(nilLiteral: ()) {
self.rawValue = 0
}
static var allZeros: GestureDirection { return self(rawValue: 0) }
static var Top: GestureDirection { return self(rawValue: 1 << 0) }
static var Down: GestureDirection { return self(rawValue: 1 << 1) }
static var Left: GestureDirection { return self(rawValue: 1 << 2) }
static var Right: GestureDirection { return self(rawValue: 1 << 3) }
}
Usage:
用法：
// Initialize:
var direction : GestureDirection = .Top | .Right
// Test:
if (direction & .Top) != nil {
// ...
}
// Add an option:
direction |= .Left
// Remove an option:
direction &= ~(.Right)
Update for Swift 2:As of Swift 2, this can be simpler done
with the new OptionSetTypeprotocol, which offers a set-like
interface (see also the recently added answers to How to create NS_OPTIONS-style bitmask enumerations in Swift?).
Swift 2 的更新：从 Swift 2 开始，这可以通过新OptionSetType协议更简单地完成，它提供了一个类似集合的接口（另请参阅最近添加的如何在 Swift 中创建 NS_OPTIONS 样式位掩码枚举的答案？）。
We just have to define the underlying storage type and the pre-defined values:
我们只需要定义底层存储类型和预定义值：
struct GestureDirection : OptionSetType {
let rawValue : UInt8
static let Top = GestureDirection(rawValue: 1 << 0)
static let Down = GestureDirection(rawValue: 1 << 1)
static let Left = GestureDirection(rawValue: 1 << 2)
static let Right = GestureDirection(rawValue: 1 << 3)
}
Usage:
用法：
// Initialize:
var direction : GestureDirection = [ .Top, .Right ]
// Test:
if direction.contains(.Top) {
// ...
}
// Add an option:
direction.insert(.Left)
// Remove an option:
direction.remove(.Right)
回答by ioopl
Swift 2.2 Version : In my case I needed to Convert the String Enum Values to be used in Localisable Strings. So added this method inside my enum.
Swift 2.2 版本：在我的情况下，我需要转换字符串枚举值以在可本地化的字符串中使用。所以在我的枚举中添加了这个方法。
enum DisplayCellTitle: String {
case Clear
func labelTitle() -> String {
switch self {
case .Clear:
return "LBL_CLEAR".localizedWithComment("Clear")
}
}
}
And then Use it like so :
然后像这样使用它：
// Get the localised value of the Cell Label Title
let lblTitle = DisplayCellTitle.labelTitle(cellTitle)()
where cellTitle passed in is just one of these CellTitle Enum Values
传入的 cellTitle 只是这些 CellTitle 枚举值之一
回答by Vincent Saluzzo
You seems to want a bitwise support for your enums, but if you regards a translation of NS_OPTIONSObjective-C in Swift, that's not represented by a Swift Enum but a structinherit from RawOptionSetType.
您似乎想要对您的枚举按位支持，但是如果您认为NS_OPTIONSSwift中Objective-C的翻译，那不是由 Swift Enum 表示，而是由struct继承自RawOptionSetType.
If you need example or instructions, you can look at this NSHipster article
如果您需要示例或说明，可以查看这篇NSHipster 文章
That's could be done with something like this :
这可以通过这样的事情来完成：
struct UIViewAutoresizing : RawOptionSetType {
init(_ value: UInt)
var value: UInt
static var None: UIViewAutoresizing { get }
static var FlexibleLeftMargin: UIViewAutoresizing { get }
static var FlexibleWidth: UIViewAutoresizing { get }
static var FlexibleRightMargin: UIViewAutoresizing { get }
static var FlexibleTopMargin: UIViewAutoresizing { get }
static var FlexibleHeight: UIViewAutoresizing { get }
static var FlexibleBottomMargin: UIViewAutoresizing { get }
}
Regards,
问候，
