#七彩画板实现

@property (nonatomic, retain)NSMutableArray *allLinesMutableArray;//用来存储所有线条的数组
@property (nonatomic, retain)NSMutableArray *colorMutableArray;//用来存储所有颜色的数组
@property (nonatomic, retain)UIButton *eraserButton;//清除橡皮擦
@property (nonatomic, retain)UIButton *allEraseButton;//清除所有的线条的橡皮擦
@end
@implementation PaintView

• (instancetype)initWithFrame:(CGRect)frame{
  if (self = [super initWithFrame:frame]) {
  _eraserButton = [UIButton buttonWithType:UIButtonTypeSystem];
  _eraserButton.frame = CGRectMake(50, 10, 100, 80);
  [_eraserButton setTitle:@"橡皮擦" forState:UIControlStateNormal];
  [_eraserButton addTarget:self action:@selector(btnAction:) forControlEvents:UIControlEventTouchUpInside];
  [self addSubview:_eraserButton];
  _allEraseButton = [UIButton buttonWithType:UIButtonTypeSystem];
  _allEraseButton.frame = CGRectMake(170, 10, 100, 80);
  [_allEraseButton setTitle:@"清除所有" forState:UIControlStateNormal];
  [_allEraseButton addTarget:self action:@selector(btn) forControlEvents:UIControlEventTouchUpInside];
  [self addSubview:_allEraseButton];
  }
  return self;
  }
  //画笔的实现方法
• (void)btnAction: (UIButton *)sender{
  if (self.allLinesMutableArray.count) {
  [self.allLinesMutableArray removeLastObject];
  [self setNeedsDisplay];
  }
  }
  //清除所有线条按钮的实现方法
• (void)btn{
  if (self.allLinesMutableArray.count) {
  [self.allLinesMutableArray removeAllObjects];
  [self setNeedsDisplay];
  }
  }

//线条数组的懒加载

• (NSMutableArray *)allLinesMutableArray{
  if (!_allLinesMutableArray) {
  _allLinesMutableArray = [[NSMutableArray alloc]initWithCapacity:2]；
  }
  return _allLinesMutableArray;
  }
  //颜色数组的懒加载
• (NSMutableArray *)colorMutableArray{
  if (!_colorMutableArray) {
  _colorMutableArray = [[NSMutableArray alloc]initWithCapacity:2];
  }
  return _colorMutableArray;
  }
  //触摸开始
• (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
  //得到绘图的起始点
  //得到触摸东西
  UITouch *touch = [touches anyObject];
  // 得到起始点
  CGPoint startPoint = [touch locationInView:self.superview];
  // 将起始点存储到一条线中
  // 先初始化一条贝塞尔曲线
  UIBezierPath *bezierLine = [UIBezierPath bezierPath];
  // 将起始点存储到线里面
  [bezierLine moveToPoint:startPoint];
  // 将贝塞尔曲线存储到数组中,这块必须使用.语法的形势，来给数组赋值
  [self.allLinesMutableArray addObject:bezierLine];
  // 每新增一条线，就给线条添加对应的颜色
  [self.colorMutableArray addObject:RGBA];
  }
  //触摸开始移动
• (void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
  // 手指触摸移动的时候，才会产生新的点，将这些所有的点都存储到贝塞尔曲线中，才能真正的组成一条线
  UITouch *touch = [touches anyObject];
  // 得到当前你在父视图上的点
  CGPoint locatiPoint = [touch locationInView:self.superview];
  // 取出开始触摸的方法中初始化好的贝塞尔曲线,因为刚才
  UIBezierPath *bezierLine = self.allLinesMutableArray.lastObject;
  // 将得到的点放到贝塞尔线中
  [bezierLine addLineToPoint:locatiPoint];
  // 重新绘制当前界面
  [self setNeedsDisplay];//调用此方法，系统会触发drawRect方法，重新绘制当前界面

}
// 重新绘制当前界面

• (void)drawRect:(CGRect)rect{
  // 设置画笔，如果是设置一种颜色的话，就用这种方法，如果想多种颜色共存的话，就是下面的方法
  // [ RGBA setStroke];
  // 开始画线
  // 遍历所有的线条。开始绘制
  for (UIBezierPath *line in self.allLinesMutableArray) {

    UIColor *linColor =   [self .colorMutableArray objectAtIndex:[self.allLinesMutableArray indexOfObject:line]];
  

// 设置每条线的画笔
[linColor setStroke];
// 设置线条粗细
[line setLineWidth:30];
// 开始绘制
[line stroke];
}
}
//触摸被打断

• (void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{

}
//触摸被打断

• (void)touchesCancelled:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{ // [self setNeedsDisplay];
  }