快速创建对象/实例 [英] create objects/instances in variables swift

问题描述

我不知道在Swift中创建实例或处理实例时如何使用变量: 例如，如何在循环中执行以下操作(创建实例):

I don't know how to use variables when creating Instances or adressing them in Swift: For exmaple how do I do following in a loop (creating Instances):

class Guest {
    let name: String
    var age: Int 
    init(name: String, age: Int) {
        self.name = name
        self.age = age
    }
}

let guests = [["ann", 1] , ["bob", 2] ...]

使循环等于:

let ann = Guest(name: "ann" , age: 1)
let bob = Guest(name: "bob" , age: 2)
...

我正在寻找这样的东西:

edit: I am looking for something like this:

for i in guests {
  let i[0] = Guest(name: i[0] , age: i[1])   

地址示例:

print(guests[0].age)
>>>1

我进行了很多搜索，但直接针对在类中创建变量的问题.

I've searched a lot but am getting directed to issues regarding creating variables in classes.

非常感谢！

推荐答案

您可以使用经典循环来做到这一点:

You can do that with a classic loop:

let input = [("Ann", 1), ("Bob", 2)]

var guests: [Guest] = []
for each in input {
    guests.append(Guest(name: each.0, age: each.1))
}

但是，使用功能性技术可以更简洁(并且避免使用var)完成此操作:

However, it can be done more concisely (and with avoidance of var) using functional techniques:

let guests = [("Ann", 1), ("Bob", 2)].map { Guest(name: $0.0, age: $0.1) }

基于字典的解决方案(Swift 4；对于Swift 3版本，只需使用经典循环即可)

Dictionary-based solution (Swift 4; for Swift 3 version just use the classic loop)

let input = [("Ann", 1), ("Bob", 2)]
let guests = Dictionary(uniqueKeysWithValues: input.map {
    ($0.0, Guest(name: $0.0, age: $0.1))
})

或者，如果两个客人的名字可能相同:

Or, if it's possible for two guests to have the same name:

let guests = Dictionary(input.map { ($0.0, Guest(name: $0.0, age: $0.1)) }) { first, second in
    // put code here to choose which of two conflicting guests to return
    return first
}

有了字典，您可以执行以下操作:

With the dictionary, you can just do:

if let annsAge = guests["Ann"]?.age {
    // do something with the value
}

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