画三条边 的 边框与圆角

// 画边框 （分为左半部分和右半部分，每次画一部分）

• (UIImage *)getEdgeLineImageWithType:(ELJSecondhandHomePageSceneFrameType)type {
  NSInteger width = self.width;
  NSInteger height = self.height;
  NSInteger cornerRadius = 5;
  NSInteger lineWidth = 1;
  // 沿着边框画，会有一半的线宽画到画板外部，留出最小距离
  CGFloat minSpace = lineWidth / 2.0;

  UIGraphicsBeginImageContextWithOptions(CGSizeMake(self.width, self.height), NO, [UIScreen mainScreen].scale);
  CGContextRef context = UIGraphicsGetCurrentContext();
  //设置颜色
  UIColor *lineColor = [UIColor lj_colorWithHex:0xededed];
  [lineColor set];
  //画线
  CGMutablePathRef path = CGPathCreateMutable();
  if (type == ELJSecondhandHomePageSceneFrameTypeLeft) { // 左侧
  CGPathMoveToPoint(path, NULL, width, minSpace);
  CGPathAddLineToPoint(path, NULL, cornerRadius + minSpace, minSpace);
  // 画左上角圆角
  CGPathAddArc(path, NULL, cornerRadius + minSpace, cornerRadius + minSpace, cornerRadius, M_PI_2 * 3, M_PI, true);
  CGPathAddLineToPoint(path, NULL, minSpace, height - cornerRadius - minSpace);
  // 画左下角圆角
  CGPathAddArc(path, NULL, cornerRadius + minSpace, height - cornerRadius - minSpace, cornerRadius, M_PI, M_PI_2, true);
  CGPathAddLineToPoint(path, NULL, width, height - minSpace);
  } else { // 右侧
  CGPathMoveToPoint(path, NULL, 0, minSpace);
  CGPathAddLineToPoint(path, NULL, width - cornerRadius - minSpace, minSpace);
  // 画右上角圆角
  CGPathAddArc(path, NULL, width - cornerRadius - minSpace, cornerRadius + minSpace, cornerRadius, M_PI_2 * 3, 0, false);
  CGPathAddLineToPoint(path, NULL, width, height - cornerRadius - minSpace);
  // 画右下角圆角
  CGPathAddArc(path, NULL, width - cornerRadius - minSpace, height - cornerRadius - minSpace, cornerRadius, 0, M_PI_2, false);
  CGPathAddLineToPoint(path, NULL, 0, height - minSpace);
  }

  CGContextSetLineWidth(context, lineWidth);
  CGContextAddPath(context, path);
  CGContextStrokePath(context);
  UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();
  CFRelease(path);
  return image;
  }