Sort Dictionary Alphabetically Cannot assign value of type '[(key: String, value: AnyObject)]' to type 'Dictionary<String, AnyObject>?'

Question

I have this Dictionary, which I am getting from a web service:

let json = try JSONSerialization.jsonObject(with: data!, options:.allowFragments) as! Dictionary<String, AnyObject>

and now I am trying to sort them alphabetically like so:

self.appDelegate.communityArray = json.sorted(by: {$0.0 < $1.0})

But I get this error:

Cannot assign value of type '[(key: String, value: AnyObject)]' to type 'Dictionary?'

What am I doing wrong?

This is how I am defining communityArray:

var communityArray: Dictionary<String, AnyObject>?

Answer 1

As mentioned in the comments a dictionary – a collection type containing key-value pairs – is unordered by definition, it cannot be sorted.

The sorted function of collection applied to a dictionary treats the dictionary for example

["foo" : 1, "bar" : false]

as an array of tuples

[(key : "foo", value : 1), (key : "bar", value : false)]

and sorts them by key (.0) or value (.1) (I suspect sorting by value Any will raise a compiler error)

The error occurs because you cannot assign an array of tuples to a variable declared as dictionary. That's almost the literal error message.

As a compromise I recommend to map the dictionary to a custom struct (similar to a tuple but better to handle)

struct Community {
    let key : String
    let value : Any
}

Your variable name already implies that you want a real array

var communityArray = [Community]()

let json = try JSONSerialization.jsonObject(with: data!) as! Dictionary<String, Any>
communityArray = json.map { Community(key: $0.0, value: $0.1 }.sorted { $0.key < $1.key }