- Swift 4 Programming Cookbook
- Keith Moon
- 281字
- 2021-07-08 10:21:28
Methods and computed variables
Say that it is important for us to know whether a person's title relates to a professional qualification that the person holds. Let's add a method to our enum to provide that information:
enum Title: String {
case mr = "Mr"
case mrs = "Mrs"
case mister = "Master"
case miss = "Miss"
case dr = "Dr"
case prof = "Prof"
case other // Inferred as "other"
func isProfessional() -> Bool {
return self == Title.dr || self == Title.prof
}
}
For the list of titles that we have defined, Dr and Prof relate to professional qualifications, so we have our method return true if self (the instance of the enum type this method is called on) is equal to the dr case, or equal to the prof case.
This functionality feels more appropriate as a computed property since whether it isProfessional or not is intrinsic to the enum itself, and we don't need to do much work to determine the answer. So, let's change this into a property:
enum Title: String {
case mr = "Mr"
case mrs = "Mrs"
case mister = "Master"
case miss = "Miss"
case dr = "Dr"
case prof = "Prof"
case other // Inferred as "other"
var isProfessional: Bool {
return self == Title.dr || self == Title.prof
}
}
Now, we can determine whether a title is a professional title by accessing the computed property on it:
let loganTitle = Title.mr
let xavierTitle = Title.prof
print(loganTitle.isProfessional) // false
print(xavierTitle.isProfessional) // true
We can't store new information on an enum, but being able to define methods and computed properties that provide extra information about the enum is really powerful.
- 一步一步學Spring Boot 2:微服務項目實戰
- Web前端開發技術:HTML、CSS、JavaScript(第3版)
- Java 開發從入門到精通(第2版)
- Objective-C應用開發全程實錄
- Python王者歸來
- 游戲程序設計教程
- Learn WebAssembly
- SAS數據統計分析與編程實踐
- 軟件工程
- 數據結構習題解析與實驗指導
- Instant Nancy Web Development
- Babylon.js Essentials
- Geospatial Development By Example with Python
- Fast Data Processing with Spark(Second Edition)
- 現代C:概念剖析和編程實踐