Dictionaries are one of the collection data types in Swift. They are unordered collections. It has key-value pairs in it. Each key is unique in a dictionary, but a key can have multiple values. It helps in efficient look-up. It maps two elements: key and value. The key and value can be of any data type.<\/p>\n
This article will discuss how to create, modify and access dictionaries in Swift. We\u2019ll also cover other concepts related to it, along with relevant examples.<\/p>\n
We can create a dictionary by writing a var\/let followed by the dictionary’s name. We can also write the type of key and value in the type declaration.<\/p>\n
Syntax for creating a dictionary.<\/strong><\/p>\n For example,<\/strong><\/p>\n Output:<\/strong><\/p>\n [2023: “Swift”, 2014: “DataFlair”]<\/p>\n We can create an empty dictionary in Swift. We do it by defining the data types of key and value.<\/p>\n Syntax for creating an empty dictionary.<\/strong><\/p>\n Example given,<\/strong><\/p>\n We can modify the elements of a dictionary. We can add elements or remove elements from it. We can also edit the values of the elements.<\/p>\n We add new elements to the dictionary by assigning values. We assign new values to a new key of the dictionary. This key is written within [] brackets while assigning the value.<\/p>\n Syntax for adding a new element<\/strong><\/p>\n For example,<\/strong><\/p>\n Output:<\/strong><\/p>\n Original:<\/strong> [2023: “Swift”, 2014: “DataFlair”] We can also remove key-value pairs from the dictionary.<\/p>\n Syntax for removing elements from dictionaries.<\/strong><\/p>\n Example given,<\/strong><\/p>\n Output:<\/strong><\/p>\n Original:<\/strong> [2020: “Dictionary”, 2014: “DataFlair”, 2023: “Swift”] We can change the values of elements in the dictionary by reassigning values to the particular key of the dictionary.<\/p>\n Syntax for changing the value.<\/strong><\/p>\n For example,<\/strong><\/p>\n Output:<\/strong><\/p>\n Original:<\/strong> [2014: “DataFlair”, 2020: “Dictionary”, 2023: “Swift”] We can access the elements of a dictionary in Swift. We can do it either by using the key or the value property of the dictionary.<\/p>\n To access keys, we use the keys property of a dictionary. For example,<\/strong><\/p>\n Output:<\/strong><\/p>\n Keys of the dictionary:<\/strong> [2020, 2023, 2014]<\/p>\n To access values, we use the values property of a dictionary.<\/p>\n Output:<\/strong><\/p>\n Values of the dictionary:<\/strong> [“Dictionary”, “DataFlair”, “Swift”]<\/p>\n Swift provides a number of methods and properties to manipulate elements and use them at our convenience.<\/p>\n Swift offers a unique property which can filter values in a dictionary. For example,<\/strong><\/p>\n Output:<\/strong><\/p>\n [“Maths”: 100, “Chemistry”: 99, “Physics”: 98]<\/p>\n We can group dictionary values based on several conditions we provide. The below example groups the subjects based on their first letter.<\/strong><\/p>\n Output:<\/strong><\/p>\n [“P”: [“Physics”, “Psychology”], “M”: [“Maths”, “Music”], “C”: [“Chemistry”], “E”: [“Economics”, “English”]]<\/p>\n We can iterate through the elements of the dictionary using a for-in loop. Example given,<\/strong><\/p>\n Output:<\/strong><\/p>\n Key:<\/strong> 2023, Value: Swift Swift provides methods to convert arrays into dictionaries and a dictionary into arrays.<\/p>\n To convert arrays into a dictionary, we need two arrays. One array will correspond to the keys in the dictionary and the second array will correspond to the values.<\/p>\n Syntax to convert an array into a dictionary.<\/strong><\/p>\n For example,<\/strong><\/p>\n Output:<\/strong><\/p>\n [2020: “Dictionary”, 2014: “DataFlair”, 2023: “Swift”]<\/p>\n We can convert a dictionary into 2 arrays. One array is made from the keys of the dictionary. Another array is made from the values of the array. For example,<\/strong><\/p>\n Output:<\/strong><\/p>\n Keys array:<\/strong> [2023, 2020, 2014] Swift dictionaries are a unique way to map data into keys and their values. It helps in handling data efficiently. In this article, we\u2019ve seen how to create and modify arrays. We\u2018ve gone through how we can access them and use them with loops. We have also covered how we can convert arrays into dictionaries and vice-versa.<\/p>\n","protected":false},"excerpt":{"rendered":" Dictionaries are one of the collection data types in Swift. They are unordered collections. It has key-value pairs in it. Each key is unique in a dictionary, but a key can have multiple values....<\/p>\n","protected":false},"author":581,"featured_media":120589,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[27789],"tags":[28453,28451,29056,28452,28287],"class_list":["post-120587","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-swift-tutorials","tag-dictionary-in-swift","tag-swift-dictionaries","tag-swift-dictionaries-with-example","tag-swift-dictionary","tag-swift-tutorials"],"yoast_head":"\nvar exampleDictionary: [keyType: valueType] = [key1: value1, key2: value2, ..., keyN: valueN]<\/pre>\n
var dictionaryExample: [Int: String] = [ 2014: \"DataFlair\", 2023: \"Swift\"]\r\nprint(dictionaryExample)<\/pre>\n
Create an empty dictionary in Swift<\/h3>\n
var dictionaryExample = [keyType: valueType]()<\/pre>\n
var dictionaryExample = [Int: String]()<\/pre>\n
Modify Dictionary in Swift<\/h3>\n
Add elements<\/h4>\n
var dictionaryExample[newKey] = newValue<\/pre>\n
var dictionaryExample = [ 2014: \"DataFlair\", 2023: \"Swift\"]\r\nprint(\"Original: \\(dictionaryExample)\")\r\ndictionaryExample[2020] = \"Dictionary\"\r\nprint(\"Updated: \\(dictionaryExample)\")<\/pre>\n
\nUpdated:<\/strong> [2023: “Swift”, 2020: “Dictionary”, 2014: “DataFlair”]<\/p>\nRemove elements<\/h4>\n
someDictionary.removeValue(forKey: keyValue)<\/pre>\n
var dictionaryExample = [2023: \"Swift\", 2020: \"Dictionary\", 2014: \"DataFlair\"]\r\nprint(\"Original: \\(dictionaryExample)\")\r\ndictionaryExample.removeValue(forKey: 2020)\r\nprint(\"Updated: \\(dictionaryExample)\")<\/pre>\n
\nUpdated:<\/strong> [2014: “DataFlair”, 2023: “Swift”]<\/p>\nChange elements<\/h4>\n
dictionaryExample[key] = newValue<\/pre>\n
var dictionaryExample = [2023: \"Swift\", 2020: \"Dictionary\", 2014: \"DataFlair\"]\r\nprint(\"Original: \\(dictionaryExample)\")\r\ndictionaryExample[2020] = \"Collections\"\r\nprint(\"Updated: \\(dictionaryExample)\")<\/pre>\n
\nUpdated:<\/strong> [2014: “DataFlair”, 2020: “Collections”, 2023: “Swift”]<\/p>\nAccess elements of Dictionary<\/h3>\n
Access keys<\/h4>\n
var dictionaryExample = [2023: \"Swift\", 2020: \"Dictionary\", 2014: \"DataFlair\"]\r\nprint(\"Keys of the dictionary: \\(dictionaryExample.keys)\")<\/pre>\n
Access values<\/h4>\n
var dictionaryExample = [2023: \"Swift\", 2020: \"Dictionary\", 2014: \"DataFlair\"]\r\nprint(\"Values of the dictionary: \\(dictionaryExample.values)\")<\/pre>\n
Swift Dictionary Properties and Methods<\/h3>\n
\n\n
\n Property\/Method\u00a0<\/b><\/td>\n Description<\/b><\/td>\n<\/tr>\n \n count<\/span><\/td>\n Gives the number of elements in a dictionary<\/span><\/td>\n<\/tr>\n \n isEmpty<\/span><\/td>\n Returns true if the dictionary is empty<\/span><\/td>\n<\/tr>\n \n shuffled()<\/span><\/td>\n Shuffles the order of elements in the dictionary<\/span><\/td>\n<\/tr>\n \n sorted()<\/span><\/td>\n Sorts the element in the dictionary<\/span><\/td>\n<\/tr>\n \n contains()<\/span><\/td>\n Check if the particular element is present in the dictionary or not<\/span><\/td>\n<\/tr>\n \n randomElement()<\/span><\/td>\n Gives random elements of the dictionary<\/span><\/td>\n<\/tr>\n \n firstIndex()<\/span><\/td>\n Gives index of the given element<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Filter in Dictionary<\/h3>\n
var subjectMarks = [\"Maths\": 100, \"Physics\": 98, \"Chemistry\": 99, \"English\": 95, \"French\": 90]\r\nvar subjectWithAGrade = subjectMarks.filter{$0.value > 95}\r\nprint(subjectWithAGrade)<\/pre>\nSwift Grouping Dictionary<\/h3>\n
var subjectMarks = [\"Maths\": 100, \"Physics\": 98, \"Chemistry\": 99, \"English\": 95, \"Music\": 90, \"Psychology\": 94, \"Economics\": 92]\r\n\r\nvar groupedSubjects = Dictionary(grouping: subjectMarks.keys) {$0.first!}\r\nprint(groupedSubjects)<\/pre>\nSwift Loop and dictionary<\/h3>\n
var dictionaryExample = [2023: \"Swift\", 2020: \"Dictionary\", 2014: \"DataFlair\"]\r\nfor (key, value) in dictionaryExample{\r\n print(\"Key: \\(key), Value: \\(value)\")\r\n}<\/pre>\n
\nKey:<\/strong> 2014, Value: DataFlair
\nKey:<\/strong> 2020, Value: Dictionary<\/p>\nArrays and Dictionaries in Swift<\/h3>\n
Arrays to dictionary<\/h4>\n
var newDictionary = Dictionary(uniqueKeysWithValues: zip(Array1, Array2)<\/pre>\n
var keysArray = [2023, 2020, 2014]\r\nvar valuesArray = [\"Swift\", \"Dictionary\", \"DataFlair\"]\r\nvar dictionaryExample = Dictionary(uniqueKeysWithValues: zip(keysArray, valuesArray))\r\nprint(dictionaryExample)<\/pre>\n
Dictionary to arrays<\/h4>\n
var dictionaryExample = [2023: \"Swift\", 2020: \"Dictionary\", 2014: \"DataFlair\"]\r\nvar keysArray = dictionaryExample.keys\r\nvar valuesArray = dictionaryExample.values\r\nprint(\"Keys array: \\(keysArray)\")\r\nprint(\"Values array: \\(valuesArray)\")<\/pre>\n
\nValues array:<\/strong> [“Swift”, “Dictionary”, “DataFlair”]<\/p>\nConclusion<\/h3>\n