ios - 画线 objective-c

Question

我是 Objective C 的初学者，我试图用 Paint 风格制作一个程序，我正在用平移手势画一条线。我可以做出手势，但问题是我无法在我用鼠标经过的地方画图，每次它重新加载我之前删除的那个点时。帮助!十分感谢!
这是该部分中的代码:

-(void)pan: (UIPanGestureRecognizer*)panGesture
{
    if(panGesture.state == UIGestureRecognizerStateChanged) {    
        _panLocation = [panGesture locationInView:self];
    }
    [self setNeedsDisplay];
}

// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect {
    CGContextRef context = UIGraphicsGetCurrentContext();
    [self drawLine:context];
}

-(void)drawLine:(CGContextRef)context {    
    if (self.tag == 0) {
        [[UIColor blackColor] setFill];
        UIGraphicsPushContext(context);
        CGContextBeginPath(context);
        CGContextAddArc(context, _panLocation.x, _panLocation.y, 4, 0, 2*M_PI, YES);
        CGContextSetAlpha(context, 1);
        CGContextFillPath(context);
    }
}

Answer 1

我想这会有所帮助
引用 draw line with gesture使用 UIPanGestureRecognizer 完成绘图的链接。
或者你可以使用触摸委托(delegate)方法来做到这一点
为此，请点击链接
draw line by touch