iOS学习笔记14—PDF的文件的创建、显示和解析

PDF的文件的创建、显示和解析在上一篇文章的这里有介绍：

图形框架:

CoreGraphics.framework

包含 Quartz 2D 绘图 API 接口 。Quartz 是 Mac OS X 系统使用的向量绘图引擎,它支持基于路径绘图、抗锯齿渲染、渐变、图片、颜色、坐标空间转换、PDF 文件的创建、显示和解析。虽然 API 基于 C 语言,但是它使用基于对象的抽象以表示基本绘图对象,这样可以让开发者可以更方便地保存并复用图像内容。

具体PDF文件的创建、显示和解析在 官方文档里面有，大家可以点击看下。这里介绍的是简单的PDF的显示和创建。

一.PDF的显示

老外写的文章 点击打开链接

首先是要创建一个项目，导入一个.pdf文件

并导入一下这个框架   我总是喜欢在.pch文件中引入

#import准备工作完成

先建一个基于UIView的PDFView

在PDFView.h文件中加载

#import 

@interface PDFView : UIView
{
    CGPDFDocumentRef pdf;
}
-(void)drawInContext:(CGContextRef)context;

@end

在PDFView.m文件中加载

#import "PDFView.h"

@implementation PDFView

- (void)dealloc
{
    CGPDFDocumentRelease(pdf);
    [super dealloc];
}


- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        
        if(self != nil)
        {
            CFURLRef pdfURL = CFBundleCopyResourceURL(CFBundleGetMainBundle(), CFSTR("苹果编码规范.PDF"), NULL, NULL);
            pdf = CGPDFDocumentCreateWithURL((CFURLRef)pdfURL);
            CFRelease(pdfURL);
        }
    }
    return self;
}

-(void)drawInContext:(CGContextRef)context
{
    // PDF page drawing expects a Lower-Left coordinate system, so we flip the coordinate system
    // before we start drawing.
    CGContextTranslateCTM(context, 0.0, self.bounds.size.height);
    CGContextScaleCTM(context, 1.0, -1.0);
    
    // Grab the first PDF page
    CGPDFPageRef page = CGPDFDocumentGetPage(pdf, 1);
    // We're about to modify the context CTM to draw the PDF page where we want it, so save the graphics state in case we want to do more drawing
    CGContextSaveGState(context);
    // CGPDFPageGetDrawingTransform provides an easy way to get the transform for a PDF page. It will scale down to fit, including any
    // base rotations necessary to display the PDF page correctly.
    CGAffineTransform pdfTransform = CGPDFPageGetDrawingTransform(page, kCGPDFCropBox, self.bounds, 0, true);
    // And apply the transform.
    CGContextConcatCTM(context, pdfTransform);
    // Finally, we draw the page and restore the graphics state for further manipulations!
    CGContextDrawPDFPage(context, page);
    CGContextRestoreGState(context);
}

- (void)drawRect:(CGRect)rect {
    [self drawInContext:UIGraphicsGetCurrentContext()];
}



@end

在mainViewController.m文件中

- (void)viewDidLoad
{
    [super viewDidLoad];
    CGRect frame = CGRectMake(0, 0, 320, 480);
    PDFView *pdfView =[[PDFView alloc]initWithFrame:frame];
    [self.view addSubview:pdfView];
    [pdfView release];

}

二.pdf的创建

pdf文档在iOS中是通过Quartz 2D库提供的api来操作的。iOS有两个图形库：

• Quartz 2D，是iOS原生的，简单易用，缺点是只有2D，仅限于iOS
• OpenGL ES，是开放标准的，2D和3D均有

使用Quartz 2D绘图到任意图形上下文（graphics context）创建pdf文件是很容易的事情。这需要：

• 指定pdf文件的位置
• 设置pdf的图形上下文（graphics context）

写了个特别简单的示例，效果如下：

完整的代码如下：

-(void)createPdf{ 
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
    NSString *saveDirectory = [paths objectAtIndex:0]; 
    NSString *saveFileName = @"myPDF.pdf"; 
    NSString *newFilePath = [saveDirectory stringByAppendingPathComponent:saveFileName]; 
    const char *filename = [newFilePath UTF8String]; 
    CGRect pageRect=CGRectMake(0, 0, 612, 792); 
    // This code block sets up our PDF Context so that we can draw to it 
    CGContextRef pdfContext; 
    CFStringRef path; 
    CFURLRef url; 
    CFMutableDictionaryRef myDictionary = NULL; 
    // Create a CFString from the filename we provide to this method when we call it 
    path = CFStringCreateWithCString (NULL, filename, 
                                      kCFStringEncodingUTF8); 
    // Create a CFURL using the CFString we just defined 
    url = CFURLCreateWithFileSystemPath (NULL, path, 
                                         kCFURLPOSIXPathStyle, 0); 
    CFRelease (path); 
    // This dictionary contains extra options mostly for ‘signing’ the PDF 
    myDictionary = CFDictionaryCreateMutable(NULL, 0, 
                                             &kCFTypeDictionaryKeyCallBacks, 
                                             &kCFTypeDictionaryValueCallBacks); 
    CFDictionarySetValue(myDictionary, kCGPDFContextTitle, CFSTR("My PDF File")); 
    CFDictionarySetValue(myDictionary, kCGPDFContextCreator, CFSTR("My Name")); 
    // Create our PDF Context with the CFURL, the CGRect we provide, and the above defined dictionary 
    pdfContext = CGPDFContextCreateWithURL (url, &pageRect, myDictionary); 
    // Cleanup our mess 
    CFRelease(myDictionary); 
    CFRelease(url); 
    // Done creating our PDF Context, now it’s time to draw to it 
    // Starts our first page 
    CGContextBeginPage (pdfContext, &pageRect); 
    // Draws a black rectangle around the page inset by 50 on all sides 
    CGContextStrokeRect(pdfContext, CGRectMake(50, 50, pageRect.size.width – 100, pageRect.size.height – 100)); 
    // Adding some text on top of the image we just added 
    CGContextSelectFont (pdfContext, "Helvetica", 30, kCGEncodingMacRoman); 
    CGContextSetTextDrawingMode (pdfContext, kCGTextFill); 
    CGContextSetRGBFillColor (pdfContext, 0, 0, 0, 1); 
    const char *text =  (char *)[@"Hello world" UTF8String]; 
    CGContextShowTextAtPoint (pdfContext, 260, 390, text, strlen(text)); 
    // End text 
    // We are done drawing to this page, let’s end it 
    // We could add as many pages as we wanted using CGContextBeginPage/CGContextEndPage 
    CGContextEndPage (pdfContext); 
    // We are done with our context now, so we release it 
    CGContextRelease (pdfContext); 
}

 

会在当前应用的Documents目录下创建一个myPDF.pdf文件，文件中只有一行字，Hello world。