Swift List Product

Swift List Product

A possible solution (now updated for Swift 2):

let rows = ["a", "b", "c"]
let cols = ["1", "2", "3"]

let squares = rows.flatMap {
    row in
    cols.map {
        col in
        row + col
    }
}
print(squares)
// [a1, a2, a3, b1, b2, b3, c1, c2, c3]

The inner map() maps the cols array to an array with the
row number prepended to each entry. The outer flatMap() maps
the rows array to an array of arrays (one for each row) and flattens the result.

Slightly more general, one could define the "product" of two
sequences as an array of tuples (pairs) with all combinations:

func product<S : SequenceType, T : SequenceType>(lseq : S, _ rseq : T) -> [(S.Generator.Element, T.Generator.Element)] {
    return lseq.flatMap { left in
        rseq.map { right in
            (left, right)
        }
    }
}

and then use it as

let squares = product(rows, cols).map(+)

Add a product in my shopping list - Creating a shopping list app

I see no outlet between your view controllers. Keep in mind that you can only show one view controller at a time. I can also see that you created a big view controller hardly. You should do it programmatically...

Go on this page : https://developer.apple.com/library/archive/referencelibrary/GettingStarted/DevelopiOSAppsSwift/CreateATableView.html , you'll learn how to create Table View, it will be really usefull for what you are trying to do.

Then you will have to pass data between controller so i suggest you go there : https://learnappmaking.com/pass-data-between-view-controllers-swift-how-to/

Swift: How To Reduce List of Non-Unique Products and Sum Quantities

You can group by the product name, put them all into a dictionary, then sum up the values.

let dict = Dictionary(grouping: originalList,
                      by: { $0.productName })
               .mapValues { $0.reduce(0, { $0 + $1.qty }) }

This gives you a [String: Int]. If you want a [(productName: String, qty: Int)] instead,

let entries = dict.map { (productName: $0, qty: $1) }

Show Quantity label when product is in cart(Swift 5)

Assuming that your card is an array of Product, you can check in your cellForRowAt indexPath whether the item at current index is present in your cart and show/hide buttons accordingly.

let productAtIndex = self.productArray[indexPath.row]

    if cart.contains(where: { (item) -> Bool in
        productAtIndex.id == item.id
    }){
        // product is in cart, show increment/decrement button
    } else {
        // product not in cart, show add button
    }

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