【iOS App】#60 畫星星蘋果 — nested loop(巢狀迴圈) 練習

Patty
彼得潘的 Swift iOS / Flutter App 開發教室
3 min readMay 24, 2021

學習迴圈畫出各種形狀:正方形、三角形、菱形、梯形排列,選擇以藍綠愛心以及紅色愛心交錯排列,希望在這段防疫階段不論藍綠全民共同一心。

Demo

code

var number = 5 // UISlider.value 需要連動 slider 的值
let imageArray = ["💙","💚","❤️"]
var outputText = ""
// 正方形排列
for i in 1...number {
for _ in 1...number {
outputText = outputText + imageArray[i % (imageArray.count)]
}
outputText = outputText + "\n"
}
// 三角形排列
for i in 1...number {
for _ in 1...i {
outputText = outputText + imageArray[i % (imageArray.count)]
}
outputText = outputText + "\n"
}
// 菱形排列
outputText = outputText + "\n\n"
for i in 1...number {
for _ in 1...i {
outputText = outputText + imageArray[i % (imageArray.count)]
}
outputText = outputText + "\n"
}
for i in 1...number {
outputText = outputText + String.init(repeating: imageArray[(number + i) % (imageArray.count)], count: number - i)
outputText = outputText + "\n"
}
// 梯形排列
for i in 1...number {
outputText = outputText + String.init(repeating: imageArray[0], count: number + 1 - i) + String.init(repeating: imageArray[1], count: 1 + 2 * (i - 1))
outputText = outputText + "\n"
}

題目

想說的…

想以迴圈製造圖案排列的時候,可以先試著帶入數字,然後推算印出來每一行的公式裡面有數字排列的則是設為 i 或 j 的部分。

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