- (void)drawRect:(CGRect)rect {
    CGContextRef context = UIGraphicsGetCurrentContext();
    //保存初始状态（压栈操作，保存一份当前图形上下文）
    CGContextSaveGState(context);
    //图形上下文移动{x,y}
    CGContextTranslateCTM(context, 50.0, 80.0);
    //图形上下文缩放{x,y}
    CGContextScaleCTM(context, 0.9, 0.9);
    //旋转
    CGContextRotateCTM(context, M_PI_4 / 4);
    //需要绘制的图片
    UIImage *image = [UIImage imageNamed:@"512"];
    CGRect rectImage = CGRectMake(0.0, 0.0, rect.size.width, (rect.size.width*image.size.height/image.size.width));
    //三种方式绘制图片
    // 1、在rect范围内完整显示图片-正常使用
        [image drawInRect:rectImage];
//    [image drawAtPoint:CGPointMake(0, 0)];
    // 2、图片上下颠倒
//        CGContextDrawImage(context, rectImage, image.CGImage);
    // 3、图片上下颠倒并拼接填充
//    CGContextDrawTiledImage(context, rectImage, image.CGImage);
    //恢复到初始状态（出栈操作，恢复一份当前图形上下文）
    
    NSString *text = @"123456789";
[text drawAtPoint:CGPointMake(10, 10) withAttributes:@{NSForegroundColorAttributeName : [UIColor blueColor], NSFontAttributeName : [UIFont systemFontOfSize:29]}];
    
    CGContextRestoreGState(context);
}

或者

- (UIImage *)complexText
{
    
    UIImage *image = self.centerShow.image;
    CGRect rect = CGRectMake(0, 0, image.size.width, image.size.height);
    
    UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    
//    CGContextTranslateCTM(context, 0, rect.size.height);
//    CGContextScaleCTM(context, 1.0, -1.0);
    
    //绘制图片
//    CGContextDrawImage(context, CGRectMake(0, 0, rect.size.width, rect.size.height), image.CGImage);
    
    [image drawInRect:CGRectMake(0, 0, rect.size.width, rect.size.height)];
    
    //做CTM变换
//    CGContextScaleCTM(context, 1.0, -1.0);
//    CGContextTranslateCTM(context, 0, -rect.size.height);
    
//    for (JHIdentifyText *obj in self.identifyTextArr) {
        NSString *text = @"123456789";
    [text drawAtPoint:CGPointMake(10, 10) withAttributes:@{NSForegroundColorAttributeName : [UIColor blueColor], NSFontAttributeName : [UIFont systemFontOfSize:29]}];
//    }
    
    UIImage *newPic = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newPic;
}