我是 swift 新手,并按照教程了解更多信息。
在下面的代码中,我定义了自定义运算符(< 和 ==),但是代码工作正常,但 Xcode 在第一行代码中显示了这些错误。
Type 'SuitedCard' does not conform to protocol 'Equatable'
Type 'SuitedCard' does not conform to protocol 'Comparable'
这是代码:
struct SuitedCard: Equatable, Comparable {
// a card can be ♥️, ♣️, ♦️, ♠️
enum Suit {
case hearts
case spades
case diamonds
case clubs
}
// the possible values of a card
enum Value: Int {
case two = 2
case three = 3
case four = 4
case five = 5
case six = 6
case seven = 7
case eight = 8
case nine = 9
case ten = 10
case jack = 11
case queen = 12
case king = 13
case ace = 14
}
// properties
let suit: Suit
let value: Value
var isFaceDown: Bool
}
var valueArray: [SuitedCard.Value] = [.ten, .jack, .queen, .king]
func ==(lhs: SuitedCard, rhs: SuitedCard) -> Bool {
for cardValue in valueArray {
if lhs.value == cardValue {
for cardValue2 in valueArray {
if rhs.value == cardValue2 {
return true
}
}
}
}
if lhs.value == rhs.value {
return true
}
return false
}
func <(lhs: SuitedCard, rhs: SuitedCard) -> Bool {
var lhsRawValue: Int
var rhsRawValue: Int
if lhs.value == .jack || lhs.value == .queen || lhs.value == .king {
lhsRawValue = 10
} else {
lhsRawValue = lhs.value.rawValue
}
if rhs.value == .jack || rhs.value == .queen || rhs.value == .king {
rhsRawValue = 10
} else {
rhsRawValue = rhs.value.rawValue
}
return lhsRawValue < rhsRawValue
}
let smaller = SuitedCard(suit: .hearts, value: .five, isFaceDown: true)
let bigger = SuitedCard(suit: .diamonds, value: .six, isFaceDown: false)
smaller >= smaller
smaller < bigger
怎么了?
最佳答案
在 Swift 3 中,协议(protocol)所需的运算符被声明为静态成员。
使用此类协议(protocol)的一种方法是将运算符定义作为静态成员移动到结构中:
struct SuitedCard: Comparable { //### Comparable implies Equatable
//...
// function for custom operator ==
static func ==(lhs: SuitedCard, rhs: SuitedCard) -> Bool {
//...
return false
}
// function for custom operator <
static func <(lhs: SuitedCard, rhs: SuitedCard) -> Bool {
//...
return false
}
}
另一种方式,您可以使用扩展声明对协议(protocol)的一致性:
struct SuitedCard {
//...
}
// function for custom operator ==
func ==(lhs: SuitedCard, rhs: SuitedCard) -> Bool {
//...
return false
}
// function for custom operator <
func <(lhs: SuitedCard, rhs: SuitedCard) -> Bool {
//...
return false
}
extension SuitedCard: Comparable {}
关于swift3 - 错误 : not conform to protocol 'Equatable' ,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/41776448/