响应者对象：继承了UIResponder的对象
触摸事件：一根或多根手指；
开始触摸：
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event;
移动：每移动一点就会调用一次；
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event;
触摸结束：
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event;
触摸事件被打断：
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event;
远程控制事件：
- (void)remoteControlReceivedWithEvent:(UIEvent *)event NS_AVAILABLE_IOS(4_0);
UIToch对象：
触摸时，会为每个手指创建一个相关联的UITouch对象，保存着跟手指相关的信息，触摸的位置、时间等；
手指移动时，系统会更新同一个UITouch对象，一直保存手指触摸的位置；
手指移开时，销毁UITouch；
获取touch对象：UITouch * touch = [touches anyObject];
触摸点所在的view
touch.view
触摸点所在的window
touch.window
获取当前触摸点的位置,相对于哪个view的位置，填nil为相对于window；
CGPoint point = [touch locationInView:touch.view];
获取上一个触摸点的位置，可以用于touchesMoved方法中
CGPoint point2 = [touch previousLocationInView:touch.view];
效果图：
画笔笔头根据画笔宽度进行改变:
原理：利用view的触摸事件，使用UIBezierPath对象进行涂鸦，UIBezierPath可以储存线段上的所有点，当成一条路径使用，并且被渲染到视图上；根据触摸点位置变化设置跟踪笔头；
我仅仅实现了效果，封装的不是很好完善，推荐这位大神的博客，封装思想很好
我有一个继承自UIView的tuyaView来作为白色涂鸦板，一个设置画笔属性的UIViewController，一个用于储存画笔属性的数据manager类；
图片
步骤：
涂鸦板view：
1、自定义一个继承自UIView的view作为涂鸦板，UIView继承自UIResponder，可以接收触摸事件； 声明三个数组属性用于存放线段以及线段属性，并且在懒加载中初始化；
2、在view的touchBegin事件中，新建一个UIBezierPath对象，使用它的moveToPoint方法将当前的触摸点设为这条线段的起点，并且将他存放到我们的线段数组中，从数据管理器中拿出线段的各种属性存放在属性数组中。初始化圆形画笔笔头，添加到涂鸦板上，中心位为触摸点；
4、监控手指的移动，将剩余线段点加入到上面创建的UIBezierPath对象中；从数组中取出贝塞尔对象，使用它的addLineToPoint方法，将移动后得到的当前点储存上；并且调用view的setNeedDisplay方法，重绘view；设置画笔笔头跟踪手指触摸移动。当触摸结束时，将笔头view移除；
5、实现view的drawRect方法：此方法用于绘制view，第四步设置了每当touchmove时都会调用此方法，从数组中拿出每一个贝塞尔对象，将它画到view上，并且取出相应的画笔样式；如果用户选取了照片就将照片绘制上去，这样绘制功能就实现了；
6、实现添加图片、退一步、清空画布、保存图片四个方法；
tuyaView.m
1 @interface tuyaView () 2 保存每条线段 3 @property (nonatomic, strong) NSMutableArray * linePaths; 4 保存每条线段的画笔大小 5 @property (nonatomic, strong) NSMutableArray * penValues; 6 保存每条线段颜色 7 @property (nonatomic, strong) NSMutableArray * penColors; 8 数据管理器 9 @property (nonatomic, strong) manager * m; 10 画笔 笔头； 11 @property (nonatomic, strong) UIView * touchPointView; 12 13 @end 14 15 @implementation tuyaView 16 懒加载中初始化各个数组 17 -(manager *)m 18 { 19 if (!_m) 20 { 21 _m = [manager shared]; 22 } 23 return _m; 24 } 25 26 -(NSMutableArray *)penValues 27 { 28 if (!_penValues) 29 { 30 _penValues = [NSMutableArray array]; 31 } 32 return _penValues; 33 } 34 35 - (NSMutableArray *)linePaths 36 { 37 if (!_linePaths) { 38 _linePaths = [NSMutableArray array]; 39 } 40 return _linePaths; 41 } 42 43 -(NSMutableArray *)penColors 44 { 45 if (!_penColors) { 46 _penColors = [NSMutableArray array]; 47 } 48 return _penColors; 49 } 50 51 52 触摸事件开始 53 -(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event 54 { 55 UITouch * touch = [touches anyObject]; 56 CGPoint point = [touch locationInView:touch.view]; 57 // 58 UIBezierPath * linePath = [UIBezierPath bezierPath]; 59 [linePath moveToPoint:point]; 60 [self.linePaths addObject:linePath]; 61 62 //保存线条粗细 63 float penValue = self.m.penValue; 64 [self.penValues addObject:[NSNumber numberWithFloat:penValue ]]; 65 //保存线条颜色 66 UIColor * penColor = self.m.penColor; 67 [self.penColors addObject:penColor]; 68 69 //创建触控点 70 CGFloat touchRadius = self.m.penValue + 10; 71 self.touchPointView = [[UIView alloc] initWithFrame:CGRectMake(point.x - touchRadius * 0.5, point.y - touchRadius * 0.5, touchRadius, touchRadius)]; 72 self.touchPointView.layer.cornerRadius = touchRadius * 0.5; 73 self.touchPointView.clipsToBounds = YES; 74 self.touchPointView.backgroundColor = [UIColor redColor]; 75 self.touchPointView.alpha = 0.5; 76 [self addSubview:self.touchPointView]; 77 } 78 79 手指移动 80 -(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event 81 { 82 UITouch * touch = [touches anyObject]; 83 CGPoint touchPoint = [touch locationInView:touch.view]; 84 85 UIBezierPath * linePath = [self.linePaths lastObject]; 86 [linePath addLineToPoint:touchPoint]; 87 88 //触控点移动 89 CGPoint current = [touch locationInView:touch.view]; 90 CGPoint pre = [touch previousLocationInView:touch.view]; 91 CGPoint center = self.touchPointView.center; 92 center.x += current.x - pre.x; 93 center.y += current.y - pre.y; 94 self.touchPointView.center = center; 95 96 [self setNeedsDisplay]; 97 } 98 99 触摸结束100 -(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event101 {102 [self.touchPointView removeFromSuperview];103 }104 105 106 绘制view107 -(void)drawRect:(CGRect)rect108 {109 [self.tuyaImage drawInRect:CGRectMake(0, 0, rect.size.width, rect.size.height)];110 111 for (int i = 0; i < self.linePaths.count; i ++)112 {113 UIBezierPath * path = self.linePaths[i];114 //取出线条宽度115 float penValue = [self.penValues[i] floatValue];116 [path setLineWidth:penValue];117 //取出线条颜色118 UIColor * color = self.penColors[i];119 [color setStroke];120 121 [path setLineJoinStyle:kCGLineJoinRound];122 [path setLineCapStyle:kCGLineCapRound];123 [path stroke];124 }125 }126 127 选取图片128 - (void)fetchPictureWith:(UIImage *)image129 {130 self.tuyaImage = image;131 [self setNeedsDisplay];132 }133 134 退后一步135 - (void)backTheLastTime136 {137 [self.linePaths removeLastObject];138 [self.penValues removeLastObject];139 [self.penColors removeLastObject];140 [self setNeedsDisplay];141 }142 143 清空画布144 - (void)cleanAllPainted145 {146 [self.linePaths removeAllObjects];147 [self.penValues removeAllObjects];148 [self.penColors removeAllObjects];149 self.tuyaImage = nil;150 [self setNeedsDisplay];151 }152 153 保存图片到手机相册154 - (void)savePicture155 {156 //1、开启上下文157 UIGraphicsBeginImageContextWithOptions(self.frame.size, YES, 0.0);158 //2、将控制器view的layer渲染到上下文，想要截啥就把哪个图层拿出来渲染159 [self.layer renderInContext:UIGraphicsGetCurrentContext()];160 //3、取出图片161 UIImage * newImage = UIGraphicsGetImageFromCurrentImageContext();162 //保存到手机相册163 UIImageWriteToSavedPhotosAlbum(newImage, nil, nil, nil);164 //关闭上下文165 UIGraphicsEndImageContext();166 } 属性控制器：1、从数据管理器中取出数据显示到自身view上。2、当画笔样式被修改时，将数据保存到管理器中。3、和tuyaView通过UINavigationController跳转，各种控件通过Storyboard实现；
PropertyView.m
1 @interface PropertyView () 2 3 @property (weak, nonatomic) IBOutlet UILabel *lalPen; 4 @property (weak, nonatomic) IBOutlet UISlider *slider; 5 6 @property (nonatomic, strong)manager * m; 7 @property (weak, nonatomic) IBOutlet UISlider *sliderRed; 8 @property (weak, nonatomic) IBOutlet UISlider *sliderGreen; 9 @property (weak, nonatomic) IBOutlet UISlider *sliderBlue;10 @property (weak, nonatomic) IBOutlet UISlider *sliderAlpha;11 12 @property (weak, nonatomic) IBOutlet UILabel *lalRed;13 @property (weak, nonatomic) IBOutlet UILabel *lalGreen;14 @property (weak, nonatomic) IBOutlet UILabel *lalBlue;15 @property (weak, nonatomic) IBOutlet UILabel *lalAlpha;16 17 @property (weak, nonatomic) IBOutlet UIView *colorView;18 19 @end20 21 @implementation PropertyView22 23 -(void)viewDidLoad24 {25 [super viewDidLoad];26 self.m = [manager shared];27 self.slider.value = self.m.penValue;28 self.lalPen.text = [NSString stringWithFormat:@"画笔宽度：%0.1lf",self.m.penValue];29 30 self.lalRed.text = self.lalRed.text = [NSString stringWithFormat:@"红：%0.0f",self.m.red];31 self.lalGreen.text = [NSString stringWithFormat:@"红：%0.0f",self.m.green];32 self.lalBlue.text = [NSString stringWithFormat:@"红：%0.0f",self.m.blue];33 self.lalAlpha.text = [NSString stringWithFormat:@"透明度：%0.0f",1 - self.m.penAlpha];34 35 self.sliderRed.value = self.m.red;36 self.sliderGreen.value = self.m.green;37 self.sliderBlue.value = self.m.blue;38 self.sliderAlpha.value = 1 - self.m.penAlpha;39 40 self.colorView.backgroundColor = self.m.penColor;41 }42 43 - (IBAction)PenSliderValueChanged:(UISlider *)sender44 {45 self.lalPen.text = [NSString stringWithFormat:@"画笔宽度：%0.1lf",sender.value];46 self.m.penValue = sender.value;47 }48 49 当4slider改变时回调同一个方法；50 - (IBAction)ColorChanged:(UISlider *)sender {51 switch (sender.tag) {52 case 1:53 self.lalRed.text = [NSString stringWithFormat:@"红：%0.0f",sender.value];54 self.m.red = sender.value;55 break;56 case 2:57 self.lalGreen.text = [NSString stringWithFormat:@"绿：%0.0f",sender.value];58 self.m.green = sender.value;59 break;60 case 3:61 self.lalBlue.text = [NSString stringWithFormat:@"蓝：%0.0f",sender.value];62 self.m.blue = sender.value;63 break;64 case 4:65 self.lalAlpha.text = [NSString stringWithFormat:@"透明度：%0.1f",sender.value];66 self.m.penAlpha = 1 - sender.value;67 break;68 69 default:70 break;71 }72 self.colorView.backgroundColor = self.m.penColor;73 }74 75 @end 数据管理器：储存画笔样式
manager.h
1 @interface manager : NSObject 2 3 @property (nonatomic, assign) CGFloat penValue; 4 5 @property (nonatomic, assign) CGFloat red; 6 @property (nonatomic, assign) CGFloat green; 7 @property (nonatomic, assign) CGFloat blue; 8 @property (nonatomic, strong) UIColor * penColor; 9 @property (nonatomic, assign) CGFloat penAlpha;10 11 + (instancetype)shared;12 13 @end
manager.m
1 + (instancetype)shared 2 { 3 static manager * m = nil; 4 static dispatch_once_t onceToken; 5 dispatch_once(&onceToken, ^{ 6 m = [[manager alloc] init]; 7 }); 8 return m; 9 }10 初始化颜色11 -(UIColor *)penColor12 {13 _penColor = [UIColor colorWithRed:self.red / 255 green:self.green/ 255 blue:self.blue / 255 alpha:1 - self.penAlpha];14 return _penColor;15 }16 17 初始化画笔宽度18 -(CGFloat)penValue19 {20 if (!_penValue) {21 _penValue = 1.0;22 }23 return _penValue;24 }