Swift declare an empty dictionary

Question

I am beginning to learn swift by following the iBook-The Swift Programming Language on Swift provided by Apple  The book says to create an empty dictionary one should use     same as while declaring array as      I declared an empty array as follows    let emptyArr         or String       But on declaring empty dictionary  I get syntax error   let emptyDict         How do I declare an empty dictionary

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I m playing with this too  It seems strange that you can just declare an empty dictionary and then add a key value pair to it like so    var emptyDictionary   Dictionary lt String  Float gt    var flexDictionary       emptyDictionary  brian     4 5 flexDictionary  key      value     ERROR   cannot assign to the result of this expression   But you can create a Dictionary that accepts different value types by using the  Any  type like so    var emptyDictionary   Dictionary lt String  Any gt    emptyDictionary  brian     4 5 emptyDictionary  mike      hello

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It is very handy for finding your way  var dict Dictionary

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Declaring  amp  Initializing Dictionaries  in Swift  Dictionary of String  var stringDict   String  String     String  String      OR  var stringDict  Dictionary lt String  String gt    Dictionary lt String  String gt      Dictionary of Int  var stringDict   String  Int     String  Int      OR  var stringDict  Dictionary lt String  Int gt    Dictionary lt String  Int gt      Dictionary of AnyObject  var stringDict   String  AnyObject     String  AnyObject      OR  var stringDict  Dictionary lt String  AnyObject gt    Dictionary lt String  AnyObject gt      Dictionary of Array of String  var stringDict   String   String      String   String       OR  var stringDict  Dictionary lt String  Array lt String gt  gt    Dictionary lt String  Array lt String gt  gt      Array of Dictionaries of String  var stringDict    String  String       String  String       OR  var stringDict  Array lt Dictionary lt String  String gt  gt    Array lt Dictionary lt String  String gt  gt

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You have to give the dictionary a type     empty dict with Ints as keys and Strings as values var namesOfIntegers   Dictionary lt Int  String gt      If the compiler can infer the type  you can use the shorter syntax  namesOfIntegers 16     sixteen     namesOfIntegers now contains 1 key-value pair namesOfIntegers          namesOfIntegers is once again an empty dictionary of type Int  String

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Use this will work   var emptyDict    String  String

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var emptyDictionary    String  String       shy   var populatedDictionary     key1    value1    key2    value2     Note  if you are going to change the contents of the dictionary over time then declare it as a var  variable   You can declare an empty dictionary as a let  constant  but it is pointless if you have the intention of changing its contents over time  since constant can t be changed after it has been initialized     Old answer   Creating an empty dictionary of type  lt String  String gt  would look as follows   var emptyDictionary   Dictionary lt String  String gt

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You can use the following code   var d1   Dictionary lt Int  Int gt    var d2    Int  Int    var d3  Dictionary lt Int  Int gt     Int   Int    var d4   Int   Int

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The Swift documentation recommends the following way to initialize an empty Dictionary   var emptyDict    String  String      I was a little confused when I first came across this question because different answers showed different ways to initialize an empty Dictionary  It turns out that there are actually a lot of ways you can do it  though some are a little redundant or overly verbose given Swift s ability to infer the type    var emptyDict    String  String    var emptyDict   Dictionary lt String  String gt    var emptyDict   String  String        var emptyDict   String  String     String  String    var emptyDict   String  String    Dictionary lt String  String gt    var emptyDict  Dictionary    String  String    var emptyDict  Dictionary   Dictionary lt String  String gt    var emptyDict  Dictionary lt String  String gt        var emptyDict  Dictionary lt String  String gt     String  String    var emptyDict  Dictionary lt String  String gt    Dictionary lt String  String gt      After you have an empty Dictionary you can add a key-value pair like this   emptyDict  some key      some value    If you want to empty your dictionary again  you can do the following   emptyDict         The types are still  lt String  String gt  because that is how it was initialized

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var dictList   String String for dictionary in swift  var arrSectionTitle   String for array in swift

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You can declare it as nil with the following   var assoc    String String    Then nice thing is you ve already typeset  notice I used var and not let  think of these as mutable and immutable   Then you can fill it later   assoc     key1     things    key2     stuff

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You can simply declare it like this   var emptyDict NSMutableDictionary

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var parking    Dictionary  lt  String  Double  gt         this adds a dictionary for a  string double  input

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You need to explicitly tell the data type or the type can be inferred when you declare anything in Swift   Swift 3  The sample below declare a dictionary with key as a Int type and the value as a String type   Method 1  Initializer  let dic   Dictionary lt Int  String gt      Method 2  Shorthand Syntax  let dic    Int String      Method 3  Dictionary Literal  var dic    1   Sample      dic has NOT to be a constant dic removeAll

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Swift 4   let dicc   NSDictionary      MARK  - This is empty dictionary let dic              MARK - This is variable dic means if you want to put variable  let dic2                            MARK - Variable example let dic3     name   Shakeel Ahmed    imageurl   https   abc abc abc etc    address   Rawalpindi Pakistan      MARK  - This is 2nd Variable Example dictionary let dic4     name   variablename   city   variablecity   zip   variablezip     MARK - Dictionary String with Any Object var dic5a    String  String      MARK - Put values in dic var dic5a     key1    value    key2   value2    key3   value3    var dic5b    String AnyObject    dic5b     name   fullname   imageurl   imgurl   language   imgurl  as  String   AnyObject   or   MARK - Dictionary String with Any Object let dic5     name   fullname   imageurl   imgurl   language   imgurl  as  String   AnyObject     MARK - More Easy Way let dic6a   NSDictionary   let dic6b   NSMutalbeDictionary

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I m usually using   var dictionary  String String        dictionary removeAll

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You can t use     unless type information is available   You need to provide it explicitly in this case   var dict   Dictionary lt String  String gt      var means it s mutable  so you can add entries to it  Conversely  if you make it a let then you cannot further modify it  let means constant    You can use the     shorthand notation if the type information can be inferred  for instance  var dict     key    value       stuff  dict          ok  I m done with it   In the last example the dictionary is known to have a type Dictionary lt String  String gt  by the first line  Note that you didn t have to specify it explicitly  but it has been inferred

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Swift   var myDictionary   Dictionary lt String  AnyObject gt

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If you want to create a generic dictionary with any type  var dictionaryData    AnyHashable Any

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