Swift - NSDictionary multidimensional - arrays

Question

currently i am working on a class which initializes an multidimensional array:
class Manager {
var data: Dictionary<String,NSDictionary>
init(data: Dictionary<String,NSDictionary>) {
func getApiData() {
getApiDataResource() { responseObject, error in
let resourceA = responseObject!
self.data["resources"] = resourceA
}
}
}
}
The responseObject which is returned asyncronously has this structure:
{
"data": [
{
id: 1
name: "Name1"
},
{
id: 2
name: "Name2"
}
],
"count": 2,
"success": true
}
The structure i want to get in my "data"-variable:
{
"resources": [
{
"resourceA":
{
"data": [
{
id: 1
name: "Name1"
},
{
id: 2
name: "Name2"
}
],
"count": 2,
"success": true
}
},
{
"resourceB": // and so on ...
}
]
}
But when saving my responseObject into my "data"-variable:
self.data["resources"] = resourceAData // this line fails
It prints:
Cannot assign to the result of this expression
Anybody could help me with this problem??
Thanks and Greetings!

Answer 1

I assume there is a function defined as follow:
func getApiDataResource(callback: (responseObject:NSDictionary?, error:NSError?) -> ()) {
// data retrieved from server at warp 8 here and other futuristic things
}
Step 1 (required)
I moved the function getApiData outside the init.
class Manager {
var data: Dictionary<String,NSDictionary>
init(data: Dictionary<String,NSDictionary>) {
getApiData()
}
func getApiData() {
getApiDataResource() { responseObject, error in
let resourceA = responseObject!
self.data["resources"] = resourceA
}
}
}
Now the compiler is complaining about this:
Use of self in method call getApiData before all store properties are initialized
and this
Return from initializer without initializing all stored properties
(As stated by you in a comment)
Fine. Let's fix it.
Step 2 (required)
class Manager {
var data: Dictionary<String,NSDictionary>
init(data: Dictionary<String,NSDictionary>) {
self.data = data
getApiData()
}
func getApiData() {
getApiDataResource() { responseObject, error in
let resourceA = responseObject!
self.data["resources"] = resourceA
}
}
}
Now it does compiles properly.
However I would adjust a couple of other things.
Step 3 (suggested)
Inside the trailing closure you are using the !. You should avoid this when possible. And you are not checking the error parameter that could be not nil.
You should use conditional unwrapping that is a safe alternative to the force unwrap (you did with !).
class Manager {
var data: Dictionary<String,NSDictionary>
init(data: Dictionary<String,NSDictionary>) {
self.data = data
getApiData()
}
func getApiData() {
getApiDataResource() { responseObject, error in
if let resourceA = responseObject where error == nil {
self.data["resources"] = resourceA
}
}
}
}
Now the code does not crash if responseObject from the closure is nil.
Step 4 (just a preference)
This is just a style preference.
Swift allows you to define your dictionary this way (as you did).
Dictionary<String,NSDictionary>
or this way:
[String:NSDictionary]
The 2 statement are equivalent. I just find more essential the second one. So...
class Manager {
var data: [String:NSDictionary]
init(data: [String:NSDictionary]) {
self.data = data
getApiData()
}
private func getApiData() {
getApiDataResource() { responseObject, error in
if let resourceA = responseObject where error == nil {
self.data["resources"] = resourceA
}
}
}
}
Let me know is this is what you need!

Answer 2

You have let data: Dictionary<String, Array<String>>, should be var data: Dictionary<String, Array<String>>