Alamofire : Updating array's values with JSON's data - arrays

Question

I have a problem when trying to update an array of struct with the JSON's data. Here's my code:
This is how the struct is defined:
Struct
struct Shot {
var title: String
var desc: String
var img: String
init(title: String, desc: String, img: String) {
self.title = title
self.desc = desc
self.img = img
}
}
Here I try to update the array, but it doesn't work:
Code
func authDribbble() {
let endURL = "https://api.dribbble.com/v1/shots/"
let token = "***"
Alamofire.request(.GET, endURL, parameters: ["access_token" : token])
.responseJSON { response in
if let JSON = response.result.value {
for i in 0..<JSON.count {
let titleA: String = String(JSON[i]["title"])
let descA: String = String(JSON[i]["description"])
let imgA: String = String(JSON[i]["images"])
self.data += [Shot(title: titleA, desc: descA, img: imgA)]
}
}
}
}
The problem is that after the function is performed, the array stays void. What's wrong?
Thank you.

Answer 1

Working under the assumption that you've called this method as follows:
authDribbble()
print("my data: \(self.data)") // Prints empty array.
The issue is that Alamofire is performing the request asynchronously. That is, the work isn't done yet when your code proceeds to the next line (the print statement). You need to implement a callback mechanism. One way to do this is to pass a function as a parameter of your authDribbble() function. That would change the function to something like:
func authDribbble(completion: () -> Void) {
// create the url
// create parameters
Alamofire.request(.GET, url!, parameters: params)
.responseJSON { response in
guard let JSON = response.result.value as? [[String : AnyObject]] else {
// Wrong type in JSON response.
print(response.result.error)
}
self.data = JSON.map { dict in
guard let title = dict["title"] as? String,
desc = dict["description"] as? String,
img = dict["images"] as? String else {
// Handle error creating Shot from JSON
}
return Shot(title: title, desc: desc, img: img)
}
completion()
}
}
}
You would then replace the call to authDribbble() with:
authDribbble() {
print("data: \(self.data)") // Prints populated array.
}