Xcode，PHP; 使用SwiftyJSON-master从PHP / MySQL检索数据时遇到问题

Question

I'm developing an iOS app with Xcode and Swift.

I need to load some data from my MySQL database in my app. I think it's reasonable to do this with JSON (or is there something against it?).

To make it easier I want to use SwiftyJSON-master .

I found this working code on SO:

class ViewController: UIViewController {

    var dict = NSDictionary()

    @IBOutlet weak var authorLbl: UILabel!
    @IBOutlet weak var quoteLbl: UILabel!

    override func viewDidLoad() {

        super.viewDidLoad()

        let urlString = "http://api.theysaidso.com/qod.json"

        if let url = NSURL(string: urlString) {

            if let data = try? NSData(contentsOfURL: url, options: []) {

                let json = JSON(data: data)

                print(json)

                let auther = json["contents"]["quotes"][0]["author"].stringValue

                let quote = json["contents"]["quotes"][0]["quote"].stringValue

                authorLbl.text = auther

                quoteLbl.text = quote
            }
        }
    }
}

But when trying it with my own PHP script it doesn't work.

I think it's because of the different outputs. The (working) PHP script from the SO post I found is like this:

{"success":{"total":1},"contents":{"quotes":[{"quote":"I put instant coffee in a microwave oven and almost went back in time.","length":"70","author":"Steven Wright","tags":["coffee","funny","humor","thetimes","time"],"category":"funny","id":"LvFg2QsKr_FoCH_lwryQ5geF"}]}}

Using my own PHP scrip output is like this: [{"a":"John Eve","b":"Cupertino","c":"Green","d":"Apple"},{"a":"Sarah Jones","b":"Berlin","c":"Red","d":"Pear"}]

The syntax seem to bee completely different.

This is my PHP script/code:

<?php
$root = realpath($_SERVER["DOCUMENT_ROOT"]);
include "$root/config.php";

$query = "SELECT * FROM users";
$stmt = $pdo->prepare($query);
$stmt->execute();

$userData = array();

while($row=$stmt->fetch(PDO::FETCH_ASSOC)){
$userData[] = $row;
}
echo json_encode($userData);
?>

What am I doing wrong? How can I influence the syntax? Or is it another problem?

PS: Is it reasonable to use this library or is something against it?

Answer 1

Update

Your php file returns a correct json format. You can access to the data simply like this:

print(json[0]["a"]) // John Eve
print(json[0]["b"]) // Cupertino
// ...
print(json[1]["a"]) // Sarah Jones
print(json[1]["c"]) // Red

Analyzing The JSON Syntax

In pursuit of understanding why is there a difference between the previous two JSON syntaxes, you need to learn about JSON Syntax .

I will try to explain that to you very briefly. I know that I'm bad at writing in English, but I'll do my best.

Curly Braces

The curly braces in json syntax represent a json object like:

{"a":"John Eve","b":"Cupertino","c":"Green","d":"Apple"} 
{"a":"Sarah Jones","b":"Berlin","c":"Red","d":"Pear"}

Square Brackets

The square brackets in json syntax represent an array of json objects like:

[
 {"a":"John Eve","b":"Cupertino","c":"Green","d":"Apple"},
 {"a":"Sarah Jones","b":"Berlin","c":"Red","d":"Pear"}
]

---

So, in the theysaidso's case, the JSON syntax represents a single JSON object that is:

The JSON object above has two JSON objects inside of it, the first object is:

"success":{"total":1}

the second one represents the contents:

Inside of the content of the JSON object, there is a JSON object called quotes which hold an array of json objects :)

Therefore, when you want to access an object of that nested json object you do this:

json["contents"]["quotes"][0]["author"].stringValue

In the above code you say: return a property of string type called "author" -["author"]- that is in a json object at index of 0 -["quotes"][0]- in the quotes array in the contents object -["contents"]- in my json object -json-!

---

As for your case, you have a single json object that is an array of JSON objects:

Therefore, when you want to access an object of that nested JSON object you do this:

json[0]["a"]

In the above code you say: return a property called "a" -["a"]- that is in a json object at index of 0 -json[0]- in the json object array -json-!

---

I hope you can understand what I'm trying to say.