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ios - 字符串格式，如循环 swift4 中的表格

问题描述

我有这个问题，我在网上寻找的所有可能的解决方案都没有帮助我。有没有办法像字符串格式一样制作表格？

我期望字符串的输出是这样的：

Category
 ITEM1     QTY     PRICE      TOTAL
 ITEM2     QTY     PRICE      TOTAL

但我的输出代码是这样的：

Category
 ITEM1         QTY     PRICE      TOTAL
 ITEM2      QTY      PRICE      TOTAL

Category
 ITEM1             QTY       PRICE        TOTAL
 ITEM2       QTY        PRICE      TOTAL

我发现项目字符串长度是为什么它们没有以我的格式正式对齐的成本，但是有没有办法解决这个问题？我是 swift 的新手。

这是我的代码：

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

标签： iosswiftswift4string-formatting

解决方案

您可以将字符串填充到定义的长度：

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     "

或者更短的形式：

// 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)

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