我正在尝试制作一个绘图应用程序。我有一个自定义 UIView:
class DrawView: UIView {
var touch : UITouch!
var lastPoint : CGPoint!
var currentPoint : CGPoint!
override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) {
touch = touches.first as! UITouch
lastPoint = touch.locationInView(self)
println(lastPoint)
}
override func touchesMoved(touches: Set<NSObject>, withEvent event: UIEvent) {
touch = touches.first as! UITouch
currentPoint = touch.locationInView(self)
self.setNeedsDisplay()
lastPoint = currentPoint
}
override func drawRect(rect: CGRect) {
var context = UIGraphicsGetCurrentContext()
CGContextSetLineWidth(context, 5)
CGContextSetStrokeColorWithColor(context, UIColor.blueColor().CGColor)
CGContextSetLineCap(context, kCGLineCapRound)
CGContextBeginPath(context)
if lastPoint != nil {
CGContextMoveToPoint(context, lastPoint.x, lastPoint.y)
CGContextAddLineToPoint(context, currentPoint.x, currentPoint.y)
}
CGContextStrokePath(context)
}
}
但是,当我运行它时,我得到的只是一个蓝点跟随我的手指,但没有线条?
我做错了什么?
最佳答案
您好,我做了一些简单的更改并修复了您的代码,希望它对以后的人有所帮助(针对 Swift 3 更新的代码):
class DrawView: UIView {
var touch : UITouch!
var lineArray : [[CGPoint]] = [[CGPoint]()]
var index = -1
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
touch = touches.first! as UITouch
let lastPoint = touch.location(in: self)
index += 1
lineArray.append([CGPoint]())
lineArray[index].append(lastPoint)
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
touch = touches.first! as UITouch
let currentPoint = touch.location(in: self)
self.setNeedsDisplay()
lineArray[index].append(currentPoint)
}
override func draw(_ rect: CGRect) {
if(index >= 0){
let context = UIGraphicsGetCurrentContext()
context!.setLineWidth(5)
context!.setStrokeColor((UIColor(red:0.00, green:0.38, blue:0.83, alpha:1.0)).cgColor)
context!.setLineCap(.round)
var j = 0
while( j <= index ){
context!.beginPath()
var i = 0
context?.move(to: lineArray[j][0])
while(i < lineArray[j].count){
context?.addLine(to: lineArray[j][i])
i += 1
}
context!.strokePath()
j += 1
}
}
}
}
关于ios - Swift - 使用CGContext用手指画图,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/30221814/