如何在 iOS 中将 UIView 转换为 PDF

有很多关于如何在App‘sUIView中显示PDF的资源.我现在的工作是从UIViews创建一个PDF.

例如，我有一个UIView，带有文本视图、UILabels、UIImages等子视图，那么如何将big UIView作为一个整体，包括其所有子视图和子视图转换为PDF？

我已经查了Apple's iOS reference张了.然而，它只谈到将文本/图像片段写入PDF文件.

我面临的问题是，我想要以PDF格式写入文件的内容很多.如果我把它们一块一块地写到PDF中，那将是一项巨大的工作. 这就是为什么我正在寻找一种方法来写入UIViews到PDF，甚至位图.

我已经try 了从Stack Overflow中的其他Q/A复制的源代码.但它只给我一个UIView边界大小的空白PDF.

-(void)createPDFfromUIView:(UIView*)aView saveToDocumentsWithFileName:(NSString*)aFilename
{
    // Creates a mutable data object for updating with binary data, like a byte array
    NSMutableData *pdfData = [NSMutableData data];

    // Points the pdf converter to the mutable data object and to the UIView to be converted
    UIGraphicsBeginPDFContextToData(pdfData, aView.bounds, nil);
    UIGraphicsBeginPDFPage();

    // draws rect to the view and thus this is captured by UIGraphicsBeginPDFContextToData
    [aView drawRect:aView.bounds];

    // remove PDF rendering context
    UIGraphicsEndPDFContext();

    // Retrieves the document directories from the iOS device
    NSArray* documentDirectories = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask,YES);

    NSString* documentDirectory = [documentDirectories objectAtIndex:0];
    NSString* documentDirectoryFilename = [documentDirectory stringByAppendingPathComponent:aFilename];

    // instructs the mutable data object to write its context to a file on disk
    [pdfData writeToFile:documentDirectoryFilename atomically:YES];
    NSLog(@"documentDirectoryFileName: %@",documentDirectoryFilename);
}