String format like a table in a loop swift4 - ios

Question

I have this problem and all possible solutions I'm looking for online hasn't helped me. Is there a way to make a table like in a string format?
What I'm expecting the output will be like this for a string:
Category
ITEM1 QTY PRICE TOTAL
ITEM2 QTY PRICE TOTAL
but my output code is like this:
Category
ITEM1 QTY PRICE TOTAL
ITEM2 QTY PRICE TOTAL
Category
ITEM1 QTY PRICE TOTAL
ITEM2 QTY PRICE TOTAL
I figured out something that the item string length is the cost why they are not aligned formally in my format, but is there a way on how to solve this issue? I'm totally new in swift.
here is my code:
for category in self.categoryList {
sentence += "Category: \(category)\n"
for items in self.productList {
if category == items.category {
grandTotal += Double(items.qty)! * Double(items.price)!
let total: Double = Double(items.qty)! * Double(items.price)!
let item = (items.item as NSString).utf8String
let qty = (items.qty as NSString).utf8String
let price = (items.price as NSString).utf8String
sentence += String(format: "%-10s%20s%15s%15.02f\n", item!, qty!, price!, total)
}
}
sentence += "\n\n"
grandTotal = 0
}
lblData.text = sentence

Answer 1

You could pad your strings to a defined length:
let elements = ["ITEM1", "QTY", "PRICE", "TOTAL"]
// without padding
var sentence = ""
for e in elements {
if !sentence.isEmpty {
sentence += " "
}
sentence += e
}
print(sentence)
// prints "ITEM1 QTY PRICE TOTAL"
// with padding
sentence = ""
for e in elements {
sentence += e.padding(toLength: 10, withPad: " ", startingAt: 0)
}
print(sentence)
// prints "ITEM1 QTY PRICE TOTAL "
Or in a shorter form:
// without padding
var sentence = elements.joined(separator: " ")
print(sentence)
// with padding
sentence = elements.map({$0.padding(toLength: 10, withPad: " ", startingAt: 0)}).joined(separator: " ")
print(sentence)