Grid
init (_ items: [Item], viewForItem: @escaping (Item) -> ItemView) {
self.items = items
self.viewForItem = viewForItem
}
-
@escapingis required because function is not used inside init but used somewhere else.
extension Array where Element: Identifiable {
func firstIndex(matching: Element) -> Int {
for index in 0..<self.count {
if self[index].id == matching.id {
return index
}
}
return 0
}
}
- Adds new function to all Arrays where elements are identifiable
- Name of the file
Array+Identifiabletells that it's identifiable extension to Array
Enum
enum FastFoodMenuItem {
case hamburger(numberOfPatties: Int)
case fries(size: FryOrderSize)
case drink(String, ounces: Int)
case cookie
}
enum FryOrderSize {
case large
case small
}
let menuItem: FastFoodMenuItem = FastFoodMenuItem.hamburger(patties: 2)
- Enums can contain extra data that's just for specific item like fries can be small or large.
Optional
enum Optional<T> {
case none
case some(T)
}
An optional is an enum.
var hello: String? var hello: Optional<String> = .none
var hello: String? = "hello" var hello: Optional<String> = .some("hello")
var hello: String? = nil var hello: Optional<String> = .none
It's possible to get the value from optional two ways
hello! // this crashes the program in case the value is none
if let safehello = hello {
print(safehello)
} else {
// do something else
}
Default
hello ?? "This is default value"
- comma in
ifstatement is like sequential&&operator meaning that the value that is assigned in first condition can be used in the second condition.
var indexOfTheOneAndOnlyFaceUpCard: Int? {
get {
var faceUpCardIndices = [Int]()
for index in cards.indices {
if cards[index].isFaceUp {
faceUpCardIndices.append(index)
}
}
if faceUpCardIndices.count == 1 {
return faceUpCardIndices.first
} else {
return nill
}
}
set {
for index in cards.indices {
if index == newValue {
cards[index].isFaceUp = true
} else {
cards[index].isFaceUp = false
}
}
}
}
- When setting new value it turns all the other cards face down
- when getting value it is going to check if there is two face up cards
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