Swift中的不可变/可变集合 [英] Immutable/Mutable Collections in Swift

问题描述

我指的是Apple的Swift编程指南，用于理解用Swift语言创建Mutable / immutable对象（Array，Dictionary，Sets，Data）。但我无法理解如何在Swift中创建不可变的集合。

I was referring to Apple's Swift programming guide for understanding creation of Mutable/ immutable objects(Array, Dictionary, Sets, Data) in Swift language. But I could't understand how to create a immutable collections in Swift.

我想在Objective-C中看到Swift中的等价物

I would like to see the equivalents in Swift for the following in Objective-C

不可变数组

NSArray *imArray = [[NSArray alloc]initWithObjects:@"First",@"Second",@"Third",nil];

可变阵列

NSMutableArray *mArray = [[NSMutableArray alloc]initWithObjects:@"First",@"Second",@"Third",nil];
[mArray addObject:@"Fourth"];

不可变词典

NSDictionary *imDictionary = [[NSDictionary alloc] initWithObjectsAndKeys:@"Value1", @"Key1", @"Value2", @"Key2", nil];

可变字典

NSMutableDictionary *mDictionary = [[NSMutableDictionary alloc]initWithObjectsAndKeys:@"Value1", @"Key1", @"Value2", @"Key2", nil];
[mDictionary setObject:@"Value3" forKey:@"Key3"];

推荐答案

数组

创建不可变数组

第一种方式：

let array = NSArray(array: ["First","Second","Third"])

第二种方式：

let array = ["First","Second","Third"]

创建可变数组

var array = ["First","Second","Third"]

将对象追加到数组

array.append("Forth")

创建不可变字典

let dictionary = ["Item 1": "description", "Item 2": "description"]

创建可变字典

var dictionary = ["Item 1": "description", "Item 2": "description"]

在字典中添加新配对

dictionary["Item 3"] = "description"

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