画布

一，绘制图片

1，获取上下文

UIGraphicsBeginImageContextWithOptions(CGSizeMake(MAINSCREEN_WIDTH, adjustScaleHeight), YES, scale);

2，绘制图片

[image drawInRect:CGRectMake(0, 0, MAINSCREEN_WIDTH, adjustScaleHeight)];

3，绘制文字

​x
NSMutableParagraphStyle *textStyle = [[NSMutableParagraphStyle defaultParagraphStyle] mutableCopy];   
textStyle.lineBreakMode = NSLineBreakByWordWrapping;        
textStyle.alignment = NSTextAlignmentCenter;        
​
CGRect nameRect = CGRectMake((MAINSCREEN_WIDTH - 80)/2, qr_Y + qr_height + 10, 80, 30);
        
[@"邀请码" drawInRect:nameRect withAttributes:@{NSFontAttributeName:[UIFont qg_regularFontOfSize:22.0f],NSForegroundColorAttributeName:UIColor.textColor3333,NSParagraphStyleAttributeName:textStyle}];

4，绘制线条

• 获取上下文CGContextRef ctx = UIGraphicsGetCurrentContext();

• 绘制白色背景

  xxxxxxxxxx
  CGRect rect = CGRectMake((MAINSCREEN_WIDTH - 128)/2, qr_Y + qr_height + 50, 128, 30);
  UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:rect cornerRadius:3];
  CGContextAddPath(ctx, path.CGPath);
  CGContextSetFillColorWithColor(ctx, [UIColor colorWithWhite:1.0 alpha:0.8].CGColor);        
  CGContextFillPath(ctx);
  

   

5，绘制结束

xxxxxxxxxx
UIImage *result = UIGraphicsGetImageFromCurrentImageContext();        
UIGraphicsEndImageContext();

二、绘制空心圆

x
  let ctx = UIGraphicsGetCurrentContext()!     
  ctx.setStrokeColor(UIColor.cyan.cgColor)    
  ctx.setLineWidth(10.0)
             
  ctx.addArc(center: CGPoint(x: width/2.0, y: height/2.0), radius: 100, startAngle: 0, endAngle: CGFloat( 2*Double.pi), clockwise: true)
  ///注意这里      
  ctx.addLine(to: CGPoint(x: width/2 + 150, y: height/2 ))   
  let path = UIBezierPath(roundedRect: CGRect(x: width/2 - 150, y: height/2 - 150, width: 300, height: 300),  cornerRadius:10.0)    
  ctx.addPath(path.cgPath)    
  ctx.closePath()     
  ctx.setFillColor(UIColor.cyan.cgColor)     
  ctx.drawPath(using: CGPathDrawingMode.fill)