Calculating total price present in shopping cart - ios

Question

is how my shopping cart looks like..
I am trying to calculate the subtotal price based on the products present in the cart dynamically. My code is here :
func displaySubTotal() {
if cartArray.count == 1 {
let p1 = Double(cartArray[0].cartItems.price)
let p2 = Double(cartArray[0].cartQuantity)
let p = Double(p1! * p2)
let x1 = Double(p)
subtotalPrice.text = "\(x1)"
}
if cartArray.count == 2 {
let p1 = Double(cartArray[0].cartItems.price)
let p2 = Double(cartArray[0].cartQuantity)
let p = Double(p1! * p2)
let q1 = Double(cartArray[1].cartItems.price)
let q2 = Double(cartArray[1].cartQuantity)
let q = Double(q1! * q2)
let x2 = Double(p + q)
subtotalPrice.text = "\(x2)"
}
if cartArray.count == 3 {
let p1 = Double(cartArray[0].cartItems.price)
let p2 = Double(cartArray[0].cartQuantity)
let p = Double(p1! * p2)
let q1 = Double(cartArray[1].cartItems.price)
let q2 = Double(cartArray[1].cartQuantity)
let q = Double(q1! * q2)
let r1 = Double(cartArray[2].cartItems.price)
let r2 = Double(cartArray[2].cartQuantity)
let r = Double(r1! * r2)
let x3 = Double(p + q + r)
subtotalPrice.text = "\(x3)"
}
if cartArray.count == 4 {
let p1 = Double(cartArray[0].cartItems.price)
let p2 = Double(cartArray[0].cartQuantity)
let p = Double(p1! * p2)
let q1 = Double(cartArray[1].cartItems.price)
let q2 = Double(cartArray[1].cartQuantity)
let q = Double(q1! * q2)
let r1 = Double(cartArray[2].cartItems.price)
let r2 = Double(cartArray[2].cartQuantity)
let r = Double(r1! * r2)
let s1 = Double(cartArray[3].cartItems.price)!
let s2 = Double(cartArray[3].cartQuantity)
let s = Double(s1 * s2)
let x4 = Double(p + q + r + s)
subtotalPrice.text = "\(x4)"
}
if cartArray.count == 5 {
let p1 = Double(cartArray[0].cartItems.price)
let p2 = Double(cartArray[0].cartQuantity)
let p = Double(p1! * p2)
let q1 = Double(cartArray[1].cartItems.price)
let q2 = Double(cartArray[1].cartQuantity)
let q = Double(q1! * q2)
let r1 = Double(cartArray[2].cartItems.price)
let r2 = Double(cartArray[2].cartQuantity)
let r = Double(r1! * r2)
let s1 = Double(cartArray[3].cartItems.price)!
let s2 = Double(cartArray[3].cartQuantity)
let s = Double(s1 * s2)
let t1 = Double(cartArray[4].cartItems.price)!
let t2 = Double(cartArray[4].cartQuantity)
let t = Double(t1 * t2)
let x5 = Double(p + q + r + s + t)
subtotalPrice.text = "\(x5)"
}
}
But I can't make it dynamic (price is needed to be updated with the delete of products instantly & addition/subtraction of quantity [using the (+ & -) buttons] of products). I'm trying this kind of thing for the first time. Please suggest me hoe to solve this! Thanks in advance..

Answer 1

Just loop over your cart items. (item_price * quantity)
func displaySubTotal() {
var total_price: Float = 0.0
for items in cartArray {
if let price = Float(items.cartItems.price) {
total_price += Float(items.cartQuantity) * price
}
}
subtotalPrice.text = "\(total_price)"
}
#objc func add(sender: UIButton) {
if cartArray[sender.tag].cartQuantity >= 0 {
cartArray[sender.tag].cartQuantity += 1
cartTableView.reloadData()
self.displaySubTotal()
}
}
#objc func sub(sender: UIButton) {
if cartArray[sender.tag].cartQuantity > 0 {
cartArray[sender.tag].cartQuantity -= 1
cartTableView.reloadData()
self.displaySubTotal()
}
}