我试图实现我可以用作背景的虚线视图。看起来有点像这样的东西:
但我似乎在我的代码中遗漏了一些东西。我试图用不同大小的点和一切来实验,但到目前为止,我只是将背景颜色设置为视图,但无论大小,颜色或间距都没有点。我错过了什么?
class DottedBackgroundView: UIView {
override func draw(_ rect: CGRect) {
guard let context = UIGraphicsGetCurrentContext() else { return }
UIColor.green.setFill()
context.fill(rect)
let drawPattern: CGPatternDrawPatternCallback = { _, context in
context.addArc(
center: CGPoint(x: 5, y: 5), radius: 2.5,
startAngle: 0, endAngle: CGFloat(2.0 * .pi),
clockwise: false)
context.setFillColor(UIColor.white.cgColor)
context.fillPath()
}
var callbacks = CGPatternCallbacks(
version: 0, drawPattern: drawPattern, releaseInfo: nil)
let pattern = CGPattern(
info: nil,
bounds: CGRect(x: 0, y: 0, width: 10, height: 10),
matrix: .identity,
xStep: 10,
yStep: 10,
tiling: .constantSpacing,
isColored: true,
callbacks: &callbacks)
let patternSpace = CGColorSpace(patternBaseSpace: nil)!
context.setFillColorSpace(patternSpace)
var alpha: CGFloat = 1.0
context.setFillPattern(pattern!, colorComponents: &alpha)
context.fill(rect)
context.addArc(
center: CGPoint(x: 5, y: 5), radius: 5.0,
startAngle: 0, endAngle: CGFloat(2.0 * .pi),
clockwise: false)
}
}
你有一个bug。只需将第二行更改为UIColor.white.setFill()
,然后将drawPattern
更改为黑色:context.setFillColor(UIColor.black.cgColor)
。
有用。我在Storyboard上设置了这个视图,但如果你从代码中添加它,试试这个:
let dottedView = DottedBackgroundView()
dottedView.translatesAutoresizingMaskIntoConstraints = false
self.view.addSubview(dottedView)
NSLayoutConstraint.activate([
dottedView.leadingAnchor.constraint(equalTo: self.view.leadingAnchor),
dottedView.trailingAnchor.constraint(equalTo: self.view.trailingAnchor),
dottedView.topAnchor.constraint(equalTo: self.view.topAnchor),
dottedView.bottomAnchor.constraint(equalTo: self.view.bottomAnchor)
])
您需要设置约束,因为您的自定义视图没有定义的大小,因此无法正确调整大小。