I have a JSON file from which I two icon names: normal and active. I use them to get the system icons, which I'd like to put inside an image array. When I load them separately it works just fine:

struct loadData: Hashable, Codable {

    //load some data...

    private var normal_name: String
    private var active_name: String

    var normal_icon: Image {
        Image(systemName: normal_name)
    }
    var active_icon: Image {
        Image(systemName: normal_name)
    }
}

When I try to put the acquired images inside an array, it throws an error:

var icon: [Image] = [
    normal_icon,
    active_icon
]

Even if I try to load them directly, it still throws the same error:

var icon: [Image] = [
    Image(systemName: normal_name),
    Image(systemName: normal_name)
]

The error I get is this:

Cannot use instance member 'normal_icon' within property initializer; property initializers run before 'self' is available

I know I can use a computed property to fix this issue, my question is:

Why am I allowed to initialize the string (normal_name) and then initialize the image (normal_icon) without getting an error, but when I do it inside the array it doesn't work?

CodePudding user response：

You don't show us the context where the code:

var icon: [Image] = [
  normal_icon,
  active_icon
]

lives, but are you doing this:

struct loadData: Hashable, Codable {

    //load some data...

    private var normal_name: String
    private var active_name: String

    var icon: [Image] = [
      normal_icon,
      active_icon
    ]
}

If so, then you have to realize that normal_icon in the array declaration is really a reference to self.normal_icon so it is referencing self while trying to set up the field icon. But the fields of the object are initialized before self is available so you

Cannot use instance member 'normal_icon' within property initializer; property initializers run before 'self' is available