错误：变量在其自身的初始值内使用？

Question

i'm trying to convert source code developed in Xcode 6.4 into Xcode 7. I'm getting some new errors. Below code which works fine in Xcode 6.4 is not working in Xcode 7

 for (index: String, category: JSON) in json["payload"]["categoryList"] {
        let category:Category = Category(category : category)
      categoryList.append(category)
    }

Answer 1

Update your code like below,

for (index: String, cat: JSON) in json["payload"]["categoryList"] {
        let category:Category = Category(category : cat)
      categoryList.append(category)
    }

Answer 2

It's good habit not to confuse the compiler by reusing variable names as parameter names and local variables in the same scope.

Better write:

for (index: String, category: JSON) in json["payload"]["categoryList"]  {
  let categoryListItem = Category(category : category)
  categoryList.append(categoryListItem)
}

or even

for (index: String, category: JSON) in json["payload"]["categoryList"] {
  categoryList.append(Category(category : category))
}

The type annotation Category is not needed. The compiler infers the type

Answer 3

for (index: String, categoryJSON: JSON) in json["payload"]["categoryList"] {
    let category:Category = Category(category : categoryJSON)
    categoryList.append(category)
}

Answer 4

Actually i found answer for my question in swift 2.0 they changed syntax of for loop

for (key,categoryJSON):(String, JSON) in json {
        //Do something you want
        let category:Category = Category(category : categoryJSON)
        categoryList.append(category)

}