iOS-View生成图片

随着分享内容的需求的不断完善，将当前页面的内容分享出去变成了产品经理的需求，之前常规的的分享显然已经不能满足，纷纷开始定制分享的图片内容。尤其以区块链相关的App特别多，作为运营拉新的手段，需要及时的将行情数据、免费赠送的token信息发送出去，激活用户的热情。通常看到的操作方式如下即：分享的图片需要上下拼接内容，上半部分显示为App名称、简介， 下半部分为注册二维码。但是行情页面的分享已经超过了常规的屏幕可见内容， 需要将tableview未显示的内容展示出来，无疑增加了难度。

下面将常用的几种View生成图片的方法做个归类：

1.将传入的View生成图片：

+ (UIImage *)makeImageWithView:(UIView *)view{
    CGSize s = view.bounds.size;
    UIGraphicsBeginImageContextWithOptions(s, NO, [UIScreen mainScreen].scale); 
    [view.layer renderInContext:UIGraphicsGetCurrentContext()];   
    UIImage*image = UIGraphicsGetImageFromCurrentImageContext();   
    UIGraphicsEndImageContext(); 
    return image;
}

2.将传入的View生成图片,可以显示layer(分享分时图、k线)

+ (UIImage *)imageFromView:(UIView *)view{
    UIGraphicsBeginImageContextWithOptions(view.bounds.size, YES, 0.0);  
    [view drawViewHierarchyInRect:view.bounds afterScreenUpdates:YES];
    UIImage *theImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return theImage;
}

3.将tableview 生成图片

+ (UIImage *)getTableViewimage:(UITableView *)tableview{
    UIImage* viewImage = nil;
    UIScrollView *scrollView = tableview;
    UIGraphicsBeginImageContextWithOptions(CGSizeMake(scrollView.contentSize.width, scrollView.contentSize.height), NO, 0.0);
    {
        CGPoint savedContentOffset = scrollView.contentOffset;
        CGRect savedFrame = scrollView.frame;

        scrollView.contentOffset = CGPointZero;
        scrollView.frame = CGRectMake(0, 0, scrollView.contentSize.width, scrollView.contentSize.height);

        [scrollView.layer renderInContext: UIGraphicsGetCurrentContext()];
        viewImage = UIGraphicsGetImageFromCurrentImageContext();

        scrollView.contentOffset = savedContentOffset;
        scrollView.frame = savedFrame;
    }
    UIGraphicsEndImageContext();
    if (viewImage != nil) {
        return viewImage;
    }
    return nil;
}

4.图片拼接

+ (UIImage *)addSlaveImage:(UIImage *)slaveImage toMasterImage:(UIImage *)masterImage {
    CGSize size;
    size.width = masterImage.size.width;
    size.height = masterImage.size.height + slaveImage.size.height;  
    UIGraphicsBeginImageContextWithOptions(size, YES, 0.0);  
    [masterImage drawInRect:CGRectMake(0, 0, masterImage.size.width, masterImage.size.height)];
    [slaveImage drawInRect:CGRectMake(0, masterImage.size.height, masterImage.size.width, slaveImage.size.height)];   
    UIImage *resultImage = UIGraphicsGetImageFromCurrentImageContext();  
    UIGraphicsEndImageContext();
    return resultImage;
}