How to fetch array of string elements with SwiftyJSON?

Question

I have a JSON that might contain an array of string elements and I want to save it to a variable. So far I did:

import SwiftyJSON    
(...)
var myUsers = [""]
if(json["arrayOfUsers"].string != nil)
{
    myUsers = json["arrayOfUsers"] //this brings an error
}

The error says:

cannot subscript a value of type JSON with an index of type string

How can I pass this array safely to my variable?

You check that json["arrayOfUsers"] is a string and then you try to assign this object to an array of strings - it won't work. Please tell us what is json["arrayOfUsers"], is it a string or an array? — Eric Aya
– Eric Aya, Commented Apr 7, 2016 at 15:27
It is an array of string, something like ["5523533","5gdsgdse","5gdsgsdb9","5432523d"] — user3766930
– user3766930, Commented Apr 7, 2016 at 15:30
@zcui93 I wrote myUsers = json["arrayOfUsers"].array but then I'm getting an error cannot assign value of type [JSON] to type [String] — user3766930
– user3766930, Commented Apr 7, 2016 at 15:33
It's because you declared myUsers to be [""] AKA [String] — zc246
– zc246, Commented Apr 7, 2016 at 15:33

Eric Aya · Accepted Answer · 2016-04-07 16:29:14Z

2

You have to get the array of Strings that SwiftyJSON has prepared when it parsed your JSON data.

I will use if let rather than != nil like you do in your question, and we're going to use SwiftyJSON's .array optional getter:

if let users = json["arrayOfUsers"].array {
    myUsers = users
}

If for any reason you get a type error, you can explicitly downcast the SwiftyJSON object itself instead of using the getter:

if let users = json["arrayOfUsers"] as? [String] {
    myUsers = users
}

Note that your array of Strings is also not created properly. Do like this:

var myUsers = [String]()

or like hits:

var myUsers: [String] = []

Both versions are equally valid and both create an empty array of strings.

edited Apr 7, 2016 at 16:29

answered Apr 7, 2016 at 15:31

Eric Aya

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9 Comments

user3766930 Over a year ago

Ok, one more question - in this case what about the declaration of myUsers? How should I declare it? var myUsers = [""] causes an error of type mismatch :(

Eric Aya Over a year ago

var myUsers = [String]() or var myUsers: [String] = []

user3766930 Over a year ago

Hm, that super weird, I'm getting this error after those changes: imgur.com/RU70gLo What might be wrong here?

Eric Aya Over a year ago

Try my second solution in the answer, with the downcast.

user3766930 Over a year ago

:) Now it underlines this: json["array... and says Ambiguous reference to member subscript :|

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