Swift Array: [AnyObject] vs. [xxxxxxxxClass] and the method "append" - arrays

Question

Here's my code. You don't need to look at all of it. I added comments where I'm confused:
class ProductData: NSObject {
var title = ""
var icon = ""
private init(dict: NSDictionary){
title = dict["title"] as! String
icon = dict["icon"] as! String
super.init()
}
class func getTheData(fromJSONPath JSONPath: String) -> [ProductData] {
let JSONData = NSData(contentsOfFile: JSONPath)!
var JSONArray = [[String : AnyObject]]()
do {
JSONArray = try NSJSONSerialization.JSONObjectWithData(JSONData, options: NSJSONReadingOptions.MutableContainers) as! [Dictionary]
} catch { print("error")}
-----------------------------------------------------------------------------------------
//↓↓↓↓↓↓↓↓↓ different: data = "[AnyObject]()" or "[ProductData]()" ↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓
var data = [AnyObject]()
// var data = [ProductData]()
for d in JSONArray {
data.append(ProductData(dict: d))
}
return data as! [ProductData]
// return data
//↑↑↑↑↑↑↑↑↑ and here: return "data as! [ProductData]" or "data" ↑↑↑↑↑↑↑↑↑↑↑↑↑↑
}
}
I use "var data = [ProductData](), retun data" first. There's no error or warning, but when I run my app, and run to the code data.append(ProductData(dict: d)), it crashes with the error: thread 1:exc_bad_access(code=1,address=0x10). What?!
I found a way to fix it: if I use var datas = [AnyObject]() and return datas as! [ProductData], it works very well.
I am so confused:
Why does [AnyObject] make the code OK?
When I use [ProductData], why does the code: data.append(ProductData(dict: d)) crash?
What is the different between [AnyObject] and [ProductData]?

Answer 1

Your original version works for me (screenshot) (only slightly modified for testing with my data). You shouldn't have to do this dance, something else is causing trouble.
I suggest cleaning up your class a bit and take advantage of Swift 2 using guard, map and error. It will be easier to debug and will work more efficiently anyway.
Here's an example. The only difference is that I'm using NSURL to access the data in my case and I've removed the icon value, but it's easy to change it back to your case.
class ProductData: NSObject {
var title = ""
private init(dict: [String : AnyObject]){
if let t = dict["title"] as? String { self.title = t }
super.init()
}
class func getTheData(fromJSONPath JSONPath: String) -> [ProductData] {
do {
// safely unwrap and typecast the values else return empty array
guard let url = NSURL(string: JSONPath),
let JSONData = NSData(contentsOfURL: url),
let JSONArray = try NSJSONSerialization.JSONObjectWithData(JSONData, options: [])
as? [[String : AnyObject]] else { return [] }
return JSONArray.map() { ProductData(dict: $0) }
} catch {
// this `error` variable is created by the `catch` mechanism
print(error)
// return empty array if unkown failure
return []
}
}
}
let test = ProductData.getTheData(fromJSONPath: "http://localhost:5678/file/test.json")
Note: I'm sure you know it but just in case for the readers, NSData(contentsOf... is a synchronous function, so it will block the main thread (unless executed from a background thread). It's better practice to use asynchronous functions when possible.