Question

我正在尝试创建一个绘图应用程序，用户只需轻轻一按即可绘制。如果用户移除了触摸，则他/她再也不能通过触摸来进行绘制。因此，只需触摸第一次并轻扫，用户就需要绘制。

在我使用的代码中，用户仍然能够按照他/她想要的次数触摸和绘制。我希望用户只能在第一次触摸时绘制。

override func touchesBegan(touches: Set<UITouch>,
                        withEvent event: UIEvent?) {
    swiped    = false
    if let touch = touches.first {
    lastPoint = touch.locationInView(self.imageView)

    }
}




override func touchesMoved(touches: Set<UITouch>,
                            withEvent event: UIEvent?){

    swiped = true;

    if let touch = touches.first {

        let currentPoint = touch.locationInView(imageView)
        UIGraphicsBeginImageContext(self.imageView.frame.size)
        self.imageView.image?.drawInRect(CGRectMake(0, 0, self.imageView.frame.size.width, self.imageView.frame.size.height))

        CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y)
        CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y)
        CGContextSetLineCap(UIGraphicsGetCurrentContext(),CGLineCap.Round)
        CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0)

        CGContextStrokePath(UIGraphicsGetCurrentContext())
        self.imageView.image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        lastPoint = currentPoint


    }


    }




override func touchesEnded(touches: Set<UITouch>,
                   withEvent event: UIEvent?) {
    if(!swiped) {
        // This is a single touch, draw a point
        UIGraphicsBeginImageContext(self.imageView.frame.size)
        self.imageView.image?.drawInRect(CGRectMake(0, 0, self.imageView.frame.size.width, self.imageView.frame.size.height))
        CGContextSetLineCap(UIGraphicsGetCurrentContext(), CGLineCap.Round)
        CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0)

        CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y)
        CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y)
        CGContextStrokePath(UIGraphicsGetCurrentContext())
        self.imageView.image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
    }
}

Answer 1

使用标志允许触摸

var allowTouches = true

func touchesBegan() {
    guard allowTouches else {
        Return
    }
    // Your logic
}

func touchesMoved() {
    guard allowTouches else {
        Return
    }
    // Your logic
}

func touchesEnded() {
    allowTouches = false
}

防止第二次触摸生效

1 个答案: