Swift优雅的实现枚举的定义及使用详解
1、枚举是用来表示值的“类型”。
2、定义枚举类型“FamilyRelationshipType”
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enum
FamilyRelationshipType {
case
GrandFather
case
GrandMother
case
Father
case
Mother
case
Brother
case
Sister
case
Son
case
Daughter
}
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3、使用枚举，指定该成员与其他成员的关系：
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struct
FamilyMember {
var name: String
var relationshipType: FamilyRelationshipType
init(name: String, relationshipType: FamilyRelationshipType) {
self.name = name
self.relationshipType = relationshipType
}
}
let sister = FamilyMember(name:
"Jacky"
, relationshipType: FamilyRelationshipType.Sister)
let brother = FamilyMember(name:
"Jack"
, relationshipType: FamilyRelationshipType.Brother)
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4、指定值定义枚举：
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enum
FamilyRelationshipType: Int {
case
GrandFather = 400
case
GrandMother = 500
case
Father = 600
case
Mother = 700
case
Brother = 800
case
Sister = 900
case
Son = 1000
case
Daugther = 1100
}
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5、Switch中使用枚举实例：
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static
func giftFor(member: FamilyMember) -> String {
switch
(member.relationshipType) {
case
.GrandFather:
return
"Book"
case
.GrandMother:
return
"Sweater"
case
.Father:
return
"Shirt"
case
.Mother:
return
"Flowers"
default
:
return
"Choclates"
}
}
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6、Swift 中也可以把每个枚举与它的值联合起来。
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enum
FamilyRelationshipType {
case
GrandFather(age: Int)
case
GrandMother(age: Int)
case
Father(age: Int)
case
Mother(age: Int)
case
Husband(age: Int)
case
Wife(age: Int)
case
Brother(age: Int)
case
Sister(age: Int)
case
Son(age: Int)
case
Daugther(age: Int)
}
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这些联合值(associated values)只可以在Switch语句里使用枚举时访问。
完整实例，根据家庭成员的年龄大小来决定具体的礼物：
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enum
FamilyRelationshipType {
case
GrandFather(age: Int)
case
GrandMother(age: Int)
case
Father(age: Int)
case
Mother(age: Int)
case
Husband(age: Int)
case
Wife(age: Int)
case
Brother(age: Int)
case
Sister(age: Int)
case
Son(age: Int)
case
Daugther(age: Int)
func gift() -> String {
switch
(self) {
case
.Brother(let age):
if
age > 10 {
return
"video games"
}
else
{
return
"toys"
}
case
.GrandFather:
return
"Book"
case
.GrandMother:
return
"Sweater"
case
.Father:
return
"Shirt"
case
.Mother:
return
"Flowers"
default
:
return
"Choclates"
}
}
}
struct
FamilyMember {
var name: String
var relationshipType: FamilyRelationshipType
init(name: String, relationshipType: FamilyRelationshipType) {
self.name = name
self.relationshipType = relationshipType
}
}
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