在playground和Project for Swift中绘图的区别

Question

我在用swift绘制东西方面非常新，最近我得到了一个应该做我需要的代码(有一个矩形地板上有10张桌子)。这段代码似乎在操场上完美地工作(右边的预览"眼睛"显示了调用我想要的图像的代码)，但是当我把它放在ViewDidLoad()下的ViewController中并运行应用程序时，什么也没有出现。我真的不确定我错过了什么，因为我复制和粘贴到我的项目的确切代码，它似乎不工作。我在故事板中没有改变任何东西我让它作为一个空白的视图控制器。任何帮助都将不胜感激。下面是代码。

//: Playground - noun: a place where people can play
import UIKit
struct Table {
    let x: Int
    let y: Int
}
var tables = [
    Table(x: 2, y: 3), Table(x: 4, y: 3), Table(x: 6, y: 3),
    Table(x: 1, y: 5), Table(x: 3, y: 5), Table(x: 5, y: 5), Table(x: 7, y: 5),
    Table(x: 2, y: 7), Table(x: 4, y: 7), Table(x: 6, y: 7)]
let cafeWidth = 8
let cafeHeight = 10
let cafeView = UIView(frame: CGRect(x: 0, y: 0, width: 300, height: 200))
cafeView.backgroundColor = UIColor(white: 0.9, alpha: 1.0)
func viewForCoordinate(#x: Int, #y: Int, #size: CGSize) -> UIView {
    let centerX = Int(cafeView.frame.size.width / CGFloat(cafeWidth)) * x
    let centerY = Int(cafeView.frame.size.height / CGFloat(cafeHeight)) * y
    let view = UIView(frame: CGRect(x: 0, y: 0, width: size.width, height: size.height))
    view.center = CGPoint(x: centerX, y: centerY)
    return view
}
// draw the grid
for row in 1..<cafeHeight {
    for column in 1..<cafeWidth {
        let gridDot = viewForCoordinate(x: row, y: column, size:    CGSize(width: 1, height: 1))
        gridDot.backgroundColor = UIColor.blackColor()
        cafeView.addSubview(gridDot)
    }
}
// draw the seats
for table in tables {
    let tableView = viewForCoordinate(x: table.x, y: table.y, size: CGSize(width: 20, height: 20))
    tableView.layer.cornerRadius = 8
    tableView.backgroundColor = UIColor(hue: 100/360.0, saturation: 0.44, brightness: 0.33, alpha: 1)
    cafeView.addSubview(tableView)
}

Answer 1

你的"cafeView"永远不会添加到ViewController中。将此添加到viewDidLoad函数的底部:self.view.addSubview(cafeView)