简单的画板

#import "MyView.h"

@interface MyView ()

{

    CGMutablePathRef pathRef;

}

@end

@implementation MyView

-(id)initWithCoder:(NSCoder *)aDecoder

{

    if (self=[super initWithCoder:aDecoder])

    {

        pathRef=CGPathCreateMutable();

       

    }

    return self;

    

}

-(void)drawRect:(CGRect)rect

{

    CGContextRef contextRef=UIGraphicsGetCurrentContext();

    CGContextAddPath(contextRef, pathRef);

    CGContextStrokePath(contextRef);

    

}

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

{

    CGPoint p=[touches.anyObject locationInView:self];

    CGPathMoveToPoint(pathRef, nil, p.x, p.y);

    

}

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

{

    CGPoint p=[touches.anyObject locationInView:self];

    CGPathAddLineToPoint(pathRef, nil, p.x, p.y);

    [self setNeedsDisplay];

}

@end