Objective c 如何在目标c中顺利绘制自由手线？

我曾使用uigraphics cgcontext在触摸屏上绘制线条…但我的线条不平滑，我的意思是边缘不平滑，所以有人能建议我如何绘制平滑线条。。？？ 这里是我用来画线的代码：

/* touchesBegan */
UITouch *touch = [touches anyObject];
lastPoint = [touch locationInView:imagevw];

/* touchesMoved */

CGFloat width = [mySlider value];
UIGraphicsBeginImageContext(imagevw.frame.size);
[imagevw.image drawInRect:CGRectMake(0, 0, imagevw.frame.size.width,imagevw.frame.size.height)];
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), width);
UITouch *touch = [touches anyObject];
mouseSwiped = YES;  
    CGPoint currentPoint = [touch locationInView:imagevw];
    CGContextBeginPath(UIGraphicsGetCurrentContext());
    CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
    CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
    CGContextStrokePath(UIGraphicsGetCurrentContext());
    imagevw.image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
lastPoint = currentPoint;





/*  touchesEnded */
/* same here */ 
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
        CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);`

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这是我的代码，我可以徒手画线，但不是平滑显示像素，我的意思是边缘不平滑

这个代码由kyoji发布，效果非常好。你可以阅读以下问题：

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使用点时不流动且不光滑。。您应该使用NSBeziePath

它花了3000行，但非常平滑，就像“竹子”工具一样

正确的方法是使用贝塞尔路径：

• 记录每一张图纸
• 用于在视图上有效地绘制
• 跟踪时，应计算bezier路径的动态定位点（不绘制事件的接触点）
• 你甚至可以记录并保存它

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我已经试过了，但还不是很顺利。。。。如果你知道任何其他可以请你寄给我，如果有任何样本代码，这将是非常有帮助的。谢谢你。。

    CGPoint midPoint(CGPoint p1, CGPoint p2)
{

    return CGPointMake((p1.x + p2.x) * 0.5, (p1.y + p2.y) * 0.5);

}

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{

    UITouch *touch = [touches anyObject];

    previousPoint1 = [touch previousLocationInView:self];
    previousPoint2 = [touch previousLocationInView:self];
    currentPoint = [touch locationInView:self];

}

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{

    UITouch *touch = [touches anyObject];

    previousPoint2 = previousPoint1;
    previousPoint1 = [touch previousLocationInView:self];
    currentPoint = [touch locationInView:self];


    // calculate mid point
    CGPoint mid1 = midPoint(previousPoint1, previousPoint2); 
    CGPoint mid2 = midPoint(currentPoint, previousPoint1);

    UIGraphicsBeginImageContext(self.imageView.frame.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    [self.imageView.image drawInRect:CGRectMake(0, 0, self.imageView.frame.size.width, self.imageView.frame.size.height)];

    CGContextMoveToPoint(context, mid1.x, mid1.y);
    // Use QuadCurve is the key
    CGContextAddQuadCurveToPoint(context, previousPoint1.x, previousPoint1.y, mid2.x, mid2.y); 

    CGContextSetLineCap(context, kCGLineCapRound);
    CGContextSetLineWidth(context, 2.0);
    CGContextSetRGBStrokeColor(context, 1.0, 0.0, 0.0, 1.0);
    CGContextStrokePath(context);

    self.imageView.image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{   
    UITouch *touch = [touches anyObject];
    pointCurrent = [touch locationInView:self.view];
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{   
    UITouch *touch = [touches anyObject];
    CGPoint pointNext = [touch locationInView:self.view];
    UIGraphicsBeginImageContext(img.frame.size);
    [img.image drawInRect:CGRectMake(0, 0, img.frame.size.width, img.frame.size.height)];
    CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 2.0);
    CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0);
    CGContextMoveToPoint(UIGraphicsGetCurrentContext(), pointCurrent.x, pointCurrent.y);
    CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), pointNext.x, pointNext.y);
    CGContextStrokePath(UIGraphicsGetCurrentContext());
    img.image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    pointCurrent = pointNext;
}