swift如何自定义数据类型Struct

2024-11-20

城镇struct示例：

struct Town{
    let name = "Linland"
    var citizens = ["Lin","Jack"]
    var resources = ["Grain": 100, "Ore":42, "Wool":72]
    
    func fortify(){
        print("Defences increased!")
    }
}

var myTown = Town()

print(myTown.citizens)
print("\(myTown.name) has \(myTown.resources["Grain"]!) bags of grain.")

//增加元素
myTown.citizens.append("Louis")
print(myTown.citizens.count)

//调用method
myTown.fortify()

initialization

struct Town{
    let name: String
    var citizens: [String]
    var resources: [String: Int]
    
    init(name: String, citizens: [String], resources: [String : Int]) {
        self.name = name
        self.citizens = citizens
        self.resources = resources
    }
}

var anotherTown = Town(name: "Nameless Island", citizens: ["Tom Hanks"], resources: ["Coconut": 100])

print(anotherTown.name)

anotherTown.citizens.append("Wilson")
print(anotherTown.citizens)

mutating func

swift struct内部不可更改属性property，哪怕是用var定义的。

比如：

struct QuizBrain{
var questionNumber = 0
questionNumber = 1 //这一行会报错
}

如果一定要更改，可以用mutating放在func的前面

struct QuizBrain{
 var questionNumber = 0
 mutating func changeNumber(){
	questionNumber = 1 
 } 
}