自制画板

效果

重点代码

@implementation GSDrawFunView{    NSMutableArray * mShapeLayerArray; // 总layer数组，里面有好多线，每条线由下面数组组成    NSMutableArray * mCurrentShapeLayerArray; // 当前画的线的layer数组    NSMutableArray * mBezierPathArray; // 所有path数组    UIColor * mCurrentColor;    UIView * mDrawBoardView;}

-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{    UITouch * touch = [touches anyObject];    CGPoint point = [touch locationInView:self];    //控制画板位置，防止线画出画板    if (point.x < mDrawBoardView.x  || point.y < mDrawBoardView.y || point.x > CGRectGetMaxX(mDrawBoardView.frame) || point.y > CGRectGetMaxY(mDrawBoardView.frame))    {        return;    }        //每条线开始画都要初始化path    UIBezierPath *  currentBezierPath = [[UIBezierPath alloc]init];    [currentBezierPath moveToPoint:point];    [mBezierPathArray addObject:currentBezierPath];        //每条线开始画都要初始化layer数组    mCurrentShapeLayerArray = [[NSMutableArray alloc]init];    }-(void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{    UITouch * touch = [touches anyObject];    CGPoint point = [touch locationInView:self];    if (point.x < mDrawBoardView.x  || point.y < mDrawBoardView.y || point.x > CGRectGetMaxX(mDrawBoardView.frame) || point.y > CGRectGetMaxY(mDrawBoardView.frame))    {        return;    }        UIBezierPath * currentBezierPath = [mBezierPathArray lastObject];    [currentBezierPath addLineToPoint:point];        CAShapeLayer * currentLayer = [[CAShapeLayer alloc]init];    currentLayer.path = currentBezierPath.CGPath;    currentLayer.fillColor = nil;    currentLayer.strokeColor = mCurrentColor.CGColor;    currentLayer.lineJoin = kCALineJoinRound; //终点    currentLayer.lineCap = kCALineCapRound; //拐角    currentLayer.lineWidth = 2;    [self.layer addSublayer:currentLayer];    [mCurrentShapeLayerArray addObject:currentLayer];        }-(void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{    //每条线画完，都要添加到layer数组里    [mShapeLayerArray addObject:mCurrentShapeLayerArray];}//改变画笔颜色-(void)changeColorForPaintBrushWithColor:(UIColor *)color{    mCurrentColor = color;    }//撤销-(void)remokeLineAction{    //删除path    UIBezierPath * lastBezierPath = [mBezierPathArray lastObject];    [lastBezierPath removeAllPoints];    [mBezierPathArray removeLastObject];        //删除layer    NSArray * lastShapeLayerArray = [mShapeLayerArray lastObject];    [mShapeLayerArray removeLastObject];    for (CAShapeLayer * layer in lastShapeLayerArray) {        [layer removeFromSuperlayer];    }    }