在CGContext中绘制UIView

Question

我正在尝试用CGContext绘制简单的UIView。我正确地绘制了一个字符串，但没有绘制UIView。

用于绘制视图的方法：

view.draw(view.layer, in: context)

但它不起作用。是否有其他方法可以在CGContext中绘制UIView

import UIKit
import CoreGraphics

let contextSize = CGSize(width: 400, height: 400)

UIGraphicsBeginImageContextWithOptions(contextSize, false, 0.0)

guard let context = UIGraphicsGetCurrentContext() else {
    fatalError("no context")
}

let size = CGSize(width: 30, height: 20)
let point = CGPoint(x: 20, y: 240)
let rect = CGRect(origin: point, size: size)

let text = "TEST"
let paragraphStyle = NSMutableParagraphStyle.default.mutableCopy() as! NSMutableParagraphStyle
paragraphStyle.minimumLineHeight = UIFont.systemFont(ofSize: 6).lineHeight
paragraphStyle.lineBreakMode = .byWordWrapping
paragraphStyle.alignment = .center
let attributes: [NSAttributedString.Key : Any] =  [.font: UIFont.systemFont(ofSize: 12),
                                                   .foregroundColor: UIColor.cyan,
                                                   .paragraphStyle: paragraphStyle]
text.draw(with: rect, options: .usesLineFragmentOrigin, attributes: attributes, context: nil)


let view = UIView()
view.backgroundColor = .magenta
view.layer.borderWidth = 2.0
view.layer.borderColor = UIColor.green.cgColor
view.frame = CGRect(origin: point, size: size)

view.draw(view.layer, in: context)

let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()

Answer 1

我相信你要找的是

view.drawHierarchy(in: view.bounds, afterScreenUpdates: true)

这将绘制到您当前设置的任何上下文。既然你做了context = UIGraphicsGetCurrentContext()，那应该已经是你的上下文了。我用你的代码试过了，看起来很管用。我得到了一个带有边框和一些文本的矩形图像。