@interface ViewController (){    Shape *_shape;}@end@implementation ViewController- (void)loadView{    //设置画板    self.view=[[SimpleDrawBoard alloc]init];    self.view.backgroundColor=[UIColor whiteColor];}- (void)viewDidLoad {    [super viewDidLoad];    }- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{    UITouch *touch=[touches anyObject];    CGPoint point=[touch locationInView:self.view];    //工厂生产形状    _shape=[Factory shapeWithType:kRud];//    _shape.fillColor=[UIColor blackColor];    [_shape addPoint:point];}- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{    UITouch *touch=[touches anyObject];    CGPoint point=[touch locationInView:self.view];    SimpleDrawBoard *board=(SimpleDrawBoard *)self.view;    [_shape addPoint:point];    [board drawShape:_shape];} - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{    UITouch *touch=[touches anyObject];    CGPoint point=[touch locationInView:self.view];    [_shape addPoint:point];    SimpleDrawBoard *board=(SimpleDrawBoard *)self.view;    [board drawShape:_shape];}////  SimpleDrawBoard.m//  Facetory-0904////  Created by apple on 14-9-4.//  Copyright (c) 2014年 apple. All rights reserved.//#import "SimpleDrawBoard.h"@interface SimpleDrawBoard(){    Shape *_shape;}@end@implementation SimpleDrawBoard- (instancetype)initWithFrame:(CGRect)frame{    self = [super initWithFrame:frame];    if (self) {        // Initialization code    }    return self;}// Only override drawRect: if you perform custom drawing.// An empty implementation adversely affects performance during animation.- (void)drawRect:(CGRect)rect{    CGContextRef context=UIGraphicsGetCurrentContext();    [_shape draw:context];}- (void)drawShape:(Shape *)shape{    _shape=shape;    [self setNeedsDisplay];}@end////  Shape.m//  Facetory-0904////  Created by apple on 14-9-4.//  Copyright (c) 2014年 apple. All rights reserved.//#import "Shape.h"@implementation Shape- (void)addPoint:(CGPoint)point{    [self doesNotRecognizeSelector:_cmd];}- (void)draw:(CGContextRef)context{    if (_fillColor)    {        [_fillColor setFill];    }    if (_lineWidth)    {        CGContextSetLineWidth(context, _lineWidth);    }    if (_strokColor)    {        [_strokColor setStroke];    }}@end////  Rud.m//  SimpleDrawBoard////  Created by apple on 14-9-4.//  Copyright (c) 2014年 戴维营教育. All rights reserved.//#import "Rud.h"#include "math.h"@interface Rud (){    CGPoint _startPoint;    CGPoint _endPoint;    CGFloat rid;    BOOL bEnd;}@end@implementation Rud- (void)addPoint:(CGPoint)position{    if (!bEnd) {        _startPoint = position;        bEnd = YES;    }    else {        _endPoint = position;        CGFloat r=(_endPoint.x - _startPoint.x)*(_endPoint.x - _startPoint.x)+(_endPoint.y - _startPoint.y)*(_endPoint.y - _startPoint.y);        rid=sqrtf(r);    }}- (void)draw:(CGContextRef)context{    [super draw:context];    CGRect rect = CGRectMake(_startPoint.x-rid, _startPoint.y-rid,rid*2,rid*2);        CGContextAddEllipseInRect(context, rect);    CGContextDrawPath(context, kCGPathEOFillStroke);}@end