Iphone 只画直线，不画平滑线

}

我正在用这个代码画线。但我希望这条线保持直线。这意味着当我移动我的触摸时，线条不应变得平滑。线条将保持笔直

我想我必须做一些类似的事情

 -(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
mouseSwiped = YES;

UITouch *touch = [touches anyObject];   
CGPoint currentPoint = [touch locationInView:scrollView];

//[self drawLine:lastPoint.x :lastPoint.y :currentPoint.x :currentPoint.y]; 
tempShapeLayer = nil;
CGMutablePathRef linePath = nil;
linePath = CGPathCreateMutable();
tempShapeLayer = [CAShapeLayer layer];

tempShapeLayer.lineWidth = 4.0f;
tempShapeLayer.lineCap = kCALineJoinMiter;
tempShapeLayer.strokeColor = [[UIColor redColor] CGColor];


CGPathMoveToPoint(linePath, NULL, lastPoint.x, lastPoint.y);
CGPathAddLineToPoint(linePath, NULL, currentPoint.x, currentPoint.y);


tempShapeLayer.path = linePath;
CGPathRelease(linePath);

[scrollView.layer addSublayer:tempShapeLayer];

lastPoint = currentPoint;

if（currentPoint.x>lastPoint.x）{
currentPoint.y=lastPoint.y；
} 
else if（currentPoint.x

如果移动子像素，将得到不需要的抗锯齿效果。我建议地板/天花板为非浮式。与非视网膜相比，使用视网膜时，这显然变得更复杂。

实际上，我必须限制触摸，这意味着如果我使用垂直或水平触摸，我必须根据它设置点。我不能从这个答案中得到答案，但这有助于我更详细地理解它。

  if (currentPoint.x > lastPoint.x){        
    currentPoint.y = lastPoint.y;
} 
else if (currentPoint.x < lastPoint.x) {
    currentPoint.x = lastPoint.x;
}