CODEWITHSUNDEEP
iosswift
Bright
Bright

Reputation: 5751

Passing functions as arguments error: Cannot convert value of type "someType.type" to expected argument type "someType"

I have a function, which takes several other functions as arguments: 

class Iterator {
    func iterateItems(itemArray: [Items], removeItem: (Items) -> Void, addItem: (inout Items) -> Void, calculateEfficiency: () -> Void) -> [Items] {
        // function body
    }
}

And I call it in its class' subclass like this: 

class WPCalculator: Iterator {

    func removeWeaponItem(item: WeaponItems) { ... }
    func addWeaponItem(item: inout WeaponItems) { ... }
    func calcWeaponDamage() { ... }

    func iterateWPItems() {
        iterateItems(itemArray: WeaponItems.weaponItems, removeItem: removeWeaponItem(item: WeaponItems), addItem: addWeaponItem(item: &WeaponItems), calculateEfficiency: calcWeaponDemage())
   }
}

Then Xcode says error on removeItem and addItem parameter:

Cannot convert value of type "WeaponItems.type" to expected argument type "WeaponItems"

Also the WeaponItems class is a subclass of Items class: 

class WeaponItems: Items { ... }

Why is that error message?

Upvotes: 1

Views: 104

Answers (3)

slashdot
slashdot

Reputation: 630

You are passing a class WeaponItems instead of class objects. Following is more correct version:

func iterateWPItems() {
    let itemsToRemove = WeaponItems() //initialize object somehow
    var itemsToAdd = WeaponItems() //initialize object somehow
    iterateItems(itemArray: WeaponItems.weaponItems, removeItem: removeWeaponItem(item: itemsToRemove), addItem: addWeaponItem(item: &itemsToAdd), calculateEfficiency: calcWeaponDemage())
}

EDIT: Sorry, I've got your problem. Than instead of calling these methods you should just pass them as arguments, so you don't have to put parentheses to a trail of method name:

func iterateWPItems() {
    iterateItems(itemArray: WeaponItems.weaponItems, removeItem: removeWeaponItem, addItem: addWeaponItem, calculateEfficiency: calcWeaponDemage)
}

Upvotes: 2

Bright
Bright

Reputation: 5751

I found the problem: the way I passed functions as arguments is wrong, it should be like this: 

func iterateWPItems() {
    iterateItems(itemArray: WeaponItems.weaponItems, removeItem: removeWeaponItem as! (Items) -> Void, addItem: addWeaponItem as! (inout Items) -> Void, calculateEfficiency: calcWeaponDemage())
}

Upvotes: 0

Hong Wei
Hong Wei

Reputation: 1407

Within your invocation of iterateItems, removeWeaponItem(item: WeaponItems), WeaponItems is a type, since it is the same as the class name WeaponItems. If you create variables of type WeaponItems, and name them differently (e.g., weaponItems) instead of WeaponItems, you probably will not run into this problem.

Upvotes: 0

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