Swift Filter Dictionary Error: Cannot Assign a Value of Type '[(_, _)]' to a Value of Type '[_:_]'

Swift filter dictionary error: Cannot assign a value of type '[(_, _)]' to a value of type '[_ : _]'

This has been fixed in Swift 4

let data = ["a": 0, "b": 42]
let filtered = data.filter { $0.value > 10 }
print(filtered) // ["b": 42]

In Swift 4, a filtered dictionary returns a dictionary.

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Original answer for Swift 2 and 3

The problem is that data is a dictionary but the result of filter is an array, so the error message says that you can't assign the result of the latter to the former.

You could just create a new variable/constant for your resulting array:

let data: [String: String] = [:]
let filtered = data.filter { $0.1 == "Test" }

Here filtered is an array of tuples: [(String, String)].

Once filtered, you can recreate a new dictionary if this is what you need:

var newData = [String:String]()
for result in filtered {
    newData[result.0] = result.1
}

If you decide not to use filter you could mutate your original dictionary or a copy of it:

var data = ["a":"Test", "b":"nope"]
for (key, value) in data {
    if value != "Test" {
        data.removeValueForKey(key)
    }
}
print(data) // ["a": "Test"]

Note: in Swift 3, removeValueForKey has been renamed removeValue(forKey:), so in this example it becomes data.removeValue(forKey: key).

Can't assign value of type Dictionary to LazyMapCollection

It may be that Dictionary.keys returned a LazyMapCollection in earlier Swift versions. In Swift 5 it is Dictionary.Keys as can be seen from the documentation, in your case

var answerKeys: Dictionary.Keys

But note that you can always access answer.keys in your code instead of assigning this to a separate property.

Swift filter and dictionaries

Just do it like this:

var namesAndAges = ["Tom": 25, "Michael": 35, "Harry": 28, "Fabien": 16]
var underAge = namesAndAges.filter({ $0.value < 18 }) // [(key: "Fabien", value: 16)]

What you do is that you use $0.value in your filter.

Cannot assign value of type '[String]' to type '[[String : Any]]'

It looks like you are trying to create a filtered list based on a search term, but your dicSearch type is an array of strings (i.e: [String]), while your searchingDic is an array of dictionaries (i.e: [[String : Any]]).

This might be confusing when coming from a different language, but in Swift, the following declaration is a dictionary:

var dict: [String: Any] = [
    "key1": "value1",
    "key2": "value2",
]

so the following:

var arrayOfdicts: [[String: Any]] = [
  ["foo": "bar"],
  ["apples": "oranges"],
  dict
]

is actually an array, containing a list of dictionaries, notice how I've put the dict declared above in the second array.

The compiler is telling you that you cannot assign a '[String]' to type '[[String : Any]]'

because this:

// example to an array of strings 
var fullList: [String] = [
    "apples",
    "bananas",
    "cucumbers"
]

// is not the same as 
var arrayOfdicts: [[String: Any]] = [
  ["foo": "bar"],
  ["apples": "oranges"],
  dict
]

The Array#filter method, iterates the array itself, and returns a new array with only the elements that return true in the return statement.

so either both your arrays need to be [String] or both your arrays need to be [[String:Any]]

example for String arrays:

// array
var fullList: [String] = [
    "apples",
    "bananas",
    "cucumbers"
]


var filteredList: [String] = []


var searchTerm = "b"

filteredList = fullList.filter{ item in
  let value = item
  return value.lowercased().contains(searchTerm)
}

print(filteredList) // prints ["bananas", "cucumbers"]

an example for filtering with array of dictionaries:

var people: [[String: Any]] = [
    ["name": "Joe"],
    ["name": "Sam"],
    ["name": "Natalie"],
    ["name": "Eve"]
]


var filteredPeople: [[String: Any]] = []

var nameFilter = "a"

filteredPeople = people.filter{ item in
  let value = item["name"] as! String
  return value.lowercased().contains(nameFilter)
}

print(filteredPeople) // prints [["name": "Sam"], ["name": "Natalie"]]

Hope this helps :)

Sorting Array returns a Dictionary

I didn't get any solution for the same to sort the dictionary, but you can do something like below.

Its works for me.

make structure of key and value.

struct STRUCT_TEMP
{
    var key : Int
    var value : [MyCustomModel]
}

create structure variable.

var structTemp : [STRUCT_TEMP] = []

convert your dictionary in structure like below:

self.structTemp = datasource.map({ STRUCT_TEMP(key: $0.key, value: $0.value) })

now you can do anything with the structTemp array. Like sorting, filter and you can also use this array everywhere you want instead of dictionary.

How to assign value to dictionary saved as Any in Swift?

The result of the type cast is immutable, you have to assign the result to a variable

var learning: Any = [ "name": "C++" ]
var dictionary = learning as! [String: String]
dictionary["name"] = "Swift"

By the way Any is the worst choice

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