我试图创建一个视图,其中包括一个可以在Xcode中预览的形状层。我不知道怎么能让它完全工作,尽管它的大部分工作。具体来说,我无法确定如何设置形状层的笔划属性,因为需要在添加层之前设置它,否则不会渲染笔划。但如果我之前设置了它,那么可检查的属性就不再工作了。我走了这么远:
import Foundation
import UIKit
@IBDesignable
class CustomView: UIView
{
@IBInspectable var layerBackgroundColor: UIColor? {
didSet {
if let actualColor = layerBackgroundColor {
layer.backgroundColor = actualColor.cgColor
} else {
layerBackgroundColor = nil
}
}
}
@IBInspectable var strokeColor: UIColor? = UIColor.red {
didSet {
if let actualColor = strokeColor {
self.shapeLayer.strokeColor = actualColor.cgColor
} else {
shapeLayer.strokeColor = nil
}
}
}
private var shapeLayer: CAShapeLayer
override func prepareForInterfaceBuilder()
{
let width = self.bounds.width
let height = self.bounds.height
shapeLayer = CAShapeLayer()
shapeLayer.frame = CGRect(x: 0, y: 0, width: width, height: height)
let path = CGMutablePath()
let middle = width/2
path.move(to:CGPoint(x:middle, y:20))
path.addLine(to:CGPoint(x:middle, y:100))
layerBackgroundColor = UIColor.gray
// If this is not set no stroke will be rendered!
strokeColor = UIColor.red
shapeLayer.path = path
shapeLayer.fillColor = nil
shapeLayer.lineJoin = kCALineJoinRound
shapeLayer.lineCap = kCALineCapRound
shapeLayer.lineWidth = 5
layer.addSublayer(shapeLayer)
}
override init(frame: CGRect)
{
shapeLayer = CAShapeLayer()
super.init(frame:frame)
}
required init?(coder aDecoder: NSCoder)
{
fatalError("init(coder:) has not been implemented")
}
}
最佳答案
您正在prepareForInterfaceBuilder中创建新的shapeLayer,因此需要在该方法中设置shapeLayer的颜色属性。可检查变量是在初始化后但在prepareForInterfaceBuilder之前分配的,因此在prepareForInterfaceBuilder中创建新的CAShapeLayer会破坏以前的分配。我假设在实践中,您将在另一个方法中为您的类执行自定义绘图(因为这个方法从未在IB之外调用)。
不管怎样,下面的代码应该可以解决您在IB上的问题,我做了四个修改,都发表了评论。。。。
import Foundation
import UIKit
@IBDesignable
class CustomView: UIView
{
@IBInspectable var layerBackgroundColor: UIColor? {
didSet {
if let actualColor = layerBackgroundColor {
layer.backgroundColor = actualColor.cgColor
} else {
layerBackgroundColor = nil
}
}
}
@IBInspectable var strokeColor: UIColor? {//1 - Maybe you want to comment out assignment to UIColor.red: = UIColor.red {
didSet {
if let actualColor = strokeColor {
self.shapeLayer.strokeColor = actualColor.cgColor
} else {
shapeLayer.strokeColor = nil
}
}
}
private var shapeLayer: CAShapeLayer
override func prepareForInterfaceBuilder()
{
let width = self.bounds.width
let height = self.bounds.height
shapeLayer = CAShapeLayer()
shapeLayer.frame = CGRect(x: 0, y: 0, width: width, height: height)
let path = CGMutablePath()
let middle = width/2
path.move(to:CGPoint(x:middle, y:20))
path.addLine(to:CGPoint(x:middle, y:100))
//2 - you probably also want to set the shapeLayer's background color to the class variable, not hardcode the class variable
//layerBackgroundColor = UIColor.gray
shapeLayer.backgroundColor = layerBackgroundColor?.cgColor
// If this is not set no stroke will be rendered!
//3 Comment the hardcoding line out
//strokeColor = UIColor.red
//4 - assign the shapeLayer's stroke color
shapeLayer.strokeColor = strokeColor?.cgColor
shapeLayer.path = path
shapeLayer.fillColor = nil
shapeLayer.lineJoin = kCALineJoinRound
shapeLayer.lineCap = kCALineCapRound
shapeLayer.lineWidth = 5
layer.addSublayer(shapeLayer)
}
override init(frame: CGRect)
{
shapeLayer = CAShapeLayer()
super.init(frame:frame)
}
required init?(coder aDecoder: NSCoder)
{
fatalError("init(coder:) has not been implemented")
}
}
关于swift - 使用IBDesignable和IBInspectable预览CAShapeLayer,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/45471312/