1.建一个view

.h文件复制以下代码

/**

*  画布

*/

@interface SKGraphicView : UIView

{

CGPoint _start;

CGPoint _move;

CGMutablePathRef _path;

NSMutableArray *_pathArray;

CGFloat _lineWidth;

UIColor *_color;

}

@property (nonatomic,assign)CGFloat lineWidth;/**< 线宽 */

@property (nonatomic,strong)UIColor *color;/**< 线的颜色 */

@property (nonatomic,strong)NSMutableArray *pathArray;

-(UIImage*)getDrawingImg;

2 .m文件

复制以下代码

- (instancetype)initWithFrame:(CGRect)frame {

if (self = [super initWithFrame:frame]) {

_move = CGPointMake(0, 0);

_start = CGPointMake(0, 0);

_lineWidth = 2;

_color = [UIColor redColor];

_pathArray = [NSMutableArray array];

//创建保存功能

UIButton *but = [UIButton buttonWithType:UIButtonTypeSystem];

but.frame = CGRectMake(0, self.bounds.size.height-60, 100, 60);

[but setTitle:@"保存至相册" forState:UIControlStateNormal];

[but addTarget:self action:@selector(savePhoto) forControlEvents:UIControlEventTouchUpInside];

[self addSubview:but];

UIButton *undoBtn = [UIButton buttonWithType:UIButtonTypeSystem];

undoBtn.frame = CGRectMake(110, self.bounds.size.height-60, 100, 60);

[undoBtn setTitle:@"撤销" forState:UIControlStateNormal];

[undoBtn addTarget:self action:@selector(undoBtnEvent) forControlEvents:UIControlEventTouchUpInside];

[self addSubview:undoBtn];

UIButton *clearBtn = [UIButton buttonWithType:UIButtonTypeSystem];

clearBtn.frame = CGRectMake(220, self.bounds.size.height-60, 100, 60);

[clearBtn setTitle:@"清除" forState:UIControlStateNormal];

[clearBtn addTarget:self action:@selector(clearBtnEvent) forControlEvents:UIControlEventTouchUpInside];

[self addSubview:clearBtn];

}

return self;

}

- (void)drawRect:(CGRect)rect {

// 获取图形上下文

CGContextRef context = UIGraphicsGetCurrentContext();

[self drawPicture:context]; //画图

}

- (void)drawPicture:(CGContextRef)context {

for (NSArray * attribute in _pathArray) {

//将路径添加到上下文中

CGPathRef pathRef = (__bridge CGPathRef)(attribute[0]);

CGContextAddPath(context, pathRef);

//设置上下文属性

[attribute[1] setStroke];

CGContextSetLineWidth(context, [attribute[2] floatValue]);

//绘制线条

CGContextDrawPath(context, kCGPathStroke);

}

}

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

UITouch *touch = [touches anyObject];

_path = CGPathCreateMutable(); //创建路径

NSArray *attributeArry = @[(__bridge id)(_path),_color,[NSNumber numberWithFloat:_lineWidth]];

[_pathArray addObject:attributeArry]; //路径及属性数组数组

_start = [touch locationInView:self]; //起始点

CGPathMoveToPoint(_path, NULL,_start.x, _start.y);

}

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

//    释放路径

CGPathRelease(_path);

}

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

UITouch *touch = [touches anyObject];

_move = [touch locationInView:self];

//将点添加到路径上

CGPathAddLineToPoint(_path, NULL, _move.x, _move.y);

[self setNeedsDisplay];

}

#pragma mark --点击事件--

- (void)savePhoto {

if (_pathArray.count) {

UIGraphicsBeginImageContext(self.frame.size);

CGContextRef context = UIGraphicsGetCurrentContext();

UIRectClip(CGRectMake(0, 0, self.frame.size.width, self.frame.size.height));

[self.layer renderInContext:context];

UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

UIImageWriteToSavedPhotosAlbum(image, self, nil, NULL);

}

else{

UIAlertView* alert = [[UIAlertView alloc]initWithTitle:@"alert" message:@"请您先绘制图形" delegate:nil cancelButtonTitle:nil otherButtonTitles:@"确定", nil];

[alert show];

}

}

-(UIImage *)getDrawingImg{

if (_pathArray.count) {

UIGraphicsBeginImageContext(self.frame.size);

CGContextRef context = UIGraphicsGetCurrentContext();

UIRectClip(CGRectMake(0, 0, self.frame.size.width, self.frame.size.height));

[self.layer renderInContext:context];

UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

return image;

}

UIAlertView* alert = [[UIAlertView alloc]initWithTitle:@"alert" message:@"请您先绘制图形" delegate:nil cancelButtonTitle:nil otherButtonTitles:@"确定", nil];

[alert show];

return nil;

}

-(void)undoBtnEvent

{

[_pathArray removeLastObject];

[self setNeedsDisplay];

}

-(void)clearBtnEvent

{

[_pathArray removeAllObjects];

[self setNeedsDisplay];

}

3在控制器中包含你建立的那个view

调用以下代码就OK 了

SKGraphicView *view = [[SKGraphicView alloc] initWithFrame:CGRectMake(0, 130, kwidth, [UIScreen mainScreen].bounds.size.height - 130)];

view.backgroundColor = [UIColor whiteColor];

view.color = [UIColor blackColor];

view.lineWidth = 10;

[self.view addSubview:view];

4. 大功告成