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Convert PDF to Image (.NET)
Convert PDF to image on Android (Xamarin)
Convert PDF to image on iOS (Xamarin)
Convert PDF to image in Windows Store apps (.NET)
Convert PDF to image in Windows Phone apps (.NET)
PDF to image in Universal Windows Store apps (.NET)
Free PDF Viewer control for Windows Forms (.NET)
How to integrate PDF Viewer control in WPF app (.NET)
Creating WPF PDF Viewer supporting bookmarks (.NET)
Cross-platform PDF Viewer using GTK# (MONO)
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Multithreaded PDF rendering (.NET)
Convert pdf to image in Silverlight app (C# sample)
How to set fallback fonts for PDF rendering (C#)
Avoiding the out-of-memory exception on rendering (C#)
PDF viewer single page application (WebAPI, AngularJS)
PDF viewer control for Windows 10 universal applications
Use custom ICC profile for CMYK to RGB conversion
PDF layers - separate images, text, annotations, graphics

PDF Forms Creation PDF Security
Conversion to PDF/A
Other topics
PDF Document Manipulation PDF Content Generation
Fixed and Flow layout document API (.NET)
Creation of grids and tables in PDF (C# sample)
How to create interactive documents using Actions (C# sample)
Text flow effects in PDF (C# sample)
How to generate ordered and bulleted lists in PDF (C# sample)
Convert HTML to PDF using flow layout API (C# sample)
How to use custom fonts for PDF generation (.NET)
Create document with differently sized pages (C#)
Create PDF documents using MONO (C#/MONO/Windows/OSX)
How to use background images for content elements (C#/PDF Kit/FlowLayout)
Add transparent images to PDF document (C#)
Draw round rect borders in PDF documents(C#)
ICC color profiles and and ICC based colors in PDF (C#)
How to use bidirectional and right to left text in PDF (C#)
Create PDF documents from XML templates (C# sample)
How to resize PDF pages and use custom stamps (C#)
Add header and footer to PDF page (.NET sample)
How to use clipping mask for drawing on PDF page
Fill graphics path with gradient brushes in PDF (Shadings)
Apitron PDF Kit and Rasterizer engine settings
Add layers to PDF page (optional content, C# sample)
How to create free text annotation with custom appearance
PDF Content Extraction PDF Navigation
PDF to TIFF conversion
Contact us if you have a PDF related question and we'll cover it in our blog.

2015-04-14

Create PDF forms in iOS applications using Xamarin PDF library by Apitron

Introduction


In addition to Xamarin Android application that was recently highlighted in one of our articles, we created a similar sample for iOS. It uses Apitron PDF Kit for pdf form generation and its PDF related code and data model are the same as used for Android app. The UI part is, of course, different but it could be generalized using Xamarin.Forms if needed.

The complete sample can be found in Samples\Xamarin.iOS folder inside the download package available on our website. It’s called CreateQuestionnaireFormSample.

Note: this application has been tested using Apitron PDF Kit for .NET (Xamarin build) version 1.0.6 and iPhone iOS simulator device with iOS 7.1 and iOS 8.2 installed.

Solution overview


Our single-view storyboard-based application starts with the launchscreen defined in launchscreen.xib and then transits to the main storyboard. 



Pic. 1 PDF form generation, iOS app demo, launch screen

The demo iOS application UI is implemented using the single storyboard containing several UITextField objects linked to corresponding outlets. These fields are being used for capturing the data and creation of the PDF form as well as for displaying loaded form data. By touching “Clear” one may reset the form.

See the device screenshot below:

Pic. 2 PDF form generation, iOS app demo, main screen

When the user clicks “Save form” it starts pdf form generation. UIAlertView notifies whether the operation was completed successfully and offers to open the default preview if needed. For some reason iOS QLPreviewController on simulator doesn’t correctly show the created PDF form (it displays empty fields) while the regular OS X preview app does. Adobe Acrobat Reader opens this file without any problems. See the device screenshot below:

Pic. 3 PDF form generation, iOS app demo, generation completed

Resulting PDF file downloaded from the iPhone simulator device is shown below:

Pic. 4 Resulting PDF form generated by CreateQuestionnaireSampleForm iOS application

Form fields are made read-only so they can’t be changed in reader app after generation. These fields store the information entered by user and can be used to retrieve the information back. This is how “Load form” works. Resulting file is being written to directory returned by the Environment.GetFolderPath (Environment.SpecialFolder.MyDocuments) call.


The code


Complete Xamarin iOS app code can be found in download package while here only the PDF generation part is being shown. It returns FlowDocument object which can later be saved.

// Creates FlowDocument that represents PDF form.
private FlowDocument CreatePDFDocument()
{
    // create documen with margin
    FlowDocument document = new FlowDocument(){Margin = new Apitron.PDF.Kit.Styles.Thickness(10)};

    // add form fields and set text values based on form data
    document.Fields.Add(new TextField("SelectedProduct", SelectedProduct){IsReadOnly = true});
    document.Fields.Add(new TextField("UsagePeriod", UsagePeriod) { IsReadOnly = true });
    document.Fields.Add(new TextField("SatisfactionLevel",SatisfactionLevel){IsReadOnly = true });
    document.Fields.Add(new TextField("UserCompanyName", UserCompanyName) 
{ IsReadOnly = true });
    document.Fields.Add(new TextField("Feedback",Feedback){IsReadOnly = true,IsMultiline = true});

    // register styles defining controls appearance
    document.StyleManager.RegisterStyle(".formHeader",new Apitron.PDF.Kit.Styles.Style(){Display = Display.Block, Font = new Font(StandardFonts.HelveticaBold, 20)});
    // set style for textblock and textbox content elements using type selectors
    document.StyleManager.RegisterStyle("TextBlock, TextBox"
new Apitron.PDF.Kit.Styles.Style() { Font = new Font(StandardFonts.Helvetica, 14)});
    // set style for textbox followed by a textblock using adjacent element selector
    document.StyleManager.RegisterStyle("TextBlock + TextBox"new Apitron.PDF.Kit.Styles.Style() { BorderColor=RgbColors.Black,Border=new Border(1),Height = 20,
Background = RgbColors.LightGray});
    // set br style using type selector
    document.StyleManager.RegisterStyle("Br"new Apitron.PDF.Kit.Styles.Style() 
{ Height = 10});

    // add form header
    document.Add(new TextBlock("Product questionnaire form"){Class = "formHeader"});
    document.Add(new TextBlock("Generated on " + 
DateTime.Now.ToString("dd/MM/yyyy HH:mm")));
    document.Add(new Hr(){Height = 2, Margin = new Thickness(0,5,0,5)});
    // add product info content
    document.Add(new TextBlock("Selected product:"));
    document.Add(new TextBox("SelectedProduct"));
    document.Add(new Br());
    // add usage info content
    document.Add(new TextBlock("Usage period:"));
    document.Add(new TextBox("UsagePeriod"));
    document.Add(new Br());
    // add satisfaction level content
    document.Add(new TextBlock("SatisfactionLevel:"));
    document.Add(new TextBox("SatisfactionLevel"));
    document.Add(new Br());
    // add company name content
    document.Add(new TextBlock("User company name:"));
    document.Add(new TextBox("UserCompanyName"));
    document.Add(new Br());
    // add feedback content
    document.Add(new TextBlock("Feedback:"));
    document.Add(new TextBox("Feedback"){Height = 100});  
    return document;
}

Load pdf form back from pdf file:

/// <summary>
/// Load form data from PDF file using given filename.
/// </summary>
public static ProductQuestionnaireForm Load(string filePath)
{
  using (Stream inputStream = File.OpenRead(filePath))
  {
     // use fixed document for reading form data
     FixedDocument pdfDocument = new FixedDocument(inputStream);
   
     // create and initialize form object instance
     ProductQuestionnaireForm form = new ApitronProductQuestionnaireForm();
     form.SelectedProduct = ((TextField)pdfDocument.AcroForm["SelectedProduct"]).Text;
     form.UsagePeriod = ((TextField)pdfDocument.AcroForm["UsagePeriod"]).Text;
     form.SatisfactionLevel=((TextField)pdfDocument.AcroForm["SatisfactionLevel"]).Text;
     form.UserCompanyName = ((TextField)pdfDocument.AcroForm["UserCompanyName"]).Text;
     form.Feedback = ((TextField)pdfDocument.AcroForm["Feedback"]).Text;

     return form;
   }       
}


Conclusion


If you need an easy to maintain and cost-effective PDF processing solution for targeting many platforms at once, Apitron PDF Kit is a good choice. It allows you to create applications and services for all modern desktop, cloud and mobile platforms. You can download the evaluation version with lots of C# samples demonstrating the API from our website (link).

We've also written a free book for you describing the API and containing ready to use code snippets. It covers most parts of the PDF specification with detailed explanations and provides real life usage examples. Contact us if you are interested or have any feedback.

Downloadable version of this article can be found by the following link [PDF].

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