ios - 在 Web View 中生成 PDF 时，如何首先将 PDF 数据写入文件
<p><p>我的应用在生成 PDF 时不断收到内存警告和随后的崩溃。有人建议我先将我的 PDF 写入文件，但没有提供扩展。</p>
<p>这是我第一次使用 iOS 生成 PDF，尽管查看了 Apple 文档 <a href="http://developer.apple.com/library/ios/#documentation/2ddrawing/conceptual/drawingprintingios/GeneratingPDF/GeneratingPDF.html" rel="noreferrer noopener nofollow">http://developer.apple.com/library/ios/#documentation/2ddrawing/conceptual/drawingprintingios/GeneratingPDF/GeneratingPDF.html</a>并搜索 SO、Google 并使用 <code>UIGraphicsBeginPDFContextToFile</code> 我只是不断收到警告/没有生成 PDF 或抛出异常，因为我只是在猜测。这个概念我还真没搞懂。 </p>
<p>有人可以提供一些关于如何首先将我的 PDF 写入文件的建议</p>
<pre><code>- (void)viewWillAppear:(BOOL)animated
{
LogCmd();
;
if (self.pdfData != nil && self.viewHasUnloaded == YES) {
self.viewHasUnloaded = NO;
;
}
}
- (void)viewDidAppear:(BOOL)animated
{
LogCmd();
;
if (self.pdfData == nil) {
// Generate PDF
;
;
}
}
- (void)generatePdf
{
NSMutableArray *pagesArray = ;
if () {
initWithCertificate:self.certificate]];
initWithCertificate:self.certificate]];
;
;
initWithCertificate:self.certificate]];
initWithCertificate:self.certificate]];
initWithCertificate:self.certificate]];
initWithCertificate:self.certificate]];
initWithCertificate:self.certificate]];
}
// Set page count on all pages
int pageNumber = 0;
for (ICCertificateComponent *page in pagesArray) {
page.pageNumber.text = ;
page.pageCount.text = ;
}
NSData *pdfData = ;
;
}
}
- (void)pdfDone:(NSData *)data
{
self.pdfData = data;
;
;
}
- (NSData *)createPdfWithPages:(NSArray *)pages
{
// Creates a mutable data object for updating with binary data, like a byte array
NSMutableData *pdfData = ;
ICCertificateComponent *firstPage = ;
UIGraphicsBeginPDFContextToData(pdfData, firstPage.contentView.bounds, nil);
for (int i = 0; i < pages.count; i++) {
ICCertificateComponent *thisPage = ;
UIGraphicsBeginPDFPageWithInfo(thisPage.contentView.bounds, nil);
CGContextRef pdfContext = UIGraphicsGetCurrentContext();
;
}
UIGraphicsEndPDFContext();
return pdfData;
}
</code></pre>
<p><strong>我的尝试</strong></p>
<pre><code> -(void)createPDFfromUIView:(UIView*)aView saveToDocumentsWithFileName:(NSString*)aFilename
{
NSArray *pages;
// Creates a mutable data object for updating with binary data, like a byte array
NSMutableData *pdfData = ;
ICCertificateComponent *firstPage = ;
UIGraphicsBeginPDFContextToData(pdfData, firstPage.contentView.bounds, nil);
for (int i = 0; i < pages.count; i++) {
ICCertificateComponent *thisPage = ;
UIGraphicsBeginPDFPageWithInfo(thisPage.contentView.bounds, nil);
CGContextRef pdfContext = UIGraphicsGetCurrentContext();
;
}
UIGraphicsBeginPDFPage();
CGContextRef currentContext = UIGraphicsGetCurrentContext();
animated:NO];
;
UIGraphicsEndPDFContext();
NSArray* documentDirectories = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask,YES);
NSString* documentDirectory = ;
NSString* documentDirectoryFilename = ;
//return pdfData;
;
}
</code></pre>
<p><strong>错误:</strong>抛出异常
<code>'NSInvalidArgumentException'，原因:'-: unrecognized selector sent to instance</code> 其中我确定</p>
<p><strong>也试过了:</strong></p>
<pre><code> - (NSString *)createPdfWithPages:(NSArray *)pages
{
@autoreleasepool {
ICCertificateComponent *firstPage = ;
NSString *docDirectory =
;
NSString *pdfPath = ;
UIGraphicsBeginPDFContextToFile(pdfPath, firstPage.contentView.bounds, nil);
for (int i = 0; i < pages.count; i++) {
ICCertificateComponent *thisPage = ;
UIGraphicsBeginPDFPageWithInfo(thisPage.contentView.bounds, nil);
CGContextRef pdfContext = UIGraphicsGetCurrentContext();
;
}
UIGraphicsEndPDFContext();
return pdfPath;
}
</code></pre>
<p>错误:<code>NSInvalidArgumentException'，原因:'-: unrecognized selector sent to instance 0x24aa4580'</code></p></p>
<br><hr><h1><strong>Best Answer-推荐答案</ strong></h1><br>
<p><p>你试试下面的代码。</p>
<pre><code>+(void)drawLineFromPoint:(CGPoint)from toPoint:(CGPoint)to
{
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, 2.0);
CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
CGFloat components[] = {0.2, 0.2, 0.2, 0.3};
CGColorRef color = CGColorCreate(colorspace, components);
CGContextSetStrokeColorWithColor(context, color);
CGContextMoveToPoint(context, from.x, from.y);
CGContextAddLineToPoint(context, to.x, to.y);
CGContextStrokePath(context);
CGColorSpaceRelease(colorspace);
CGColorRelease(color);
}
+(void)drawText
{
NSString* textToDraw = @"Hello World";
CFStringRef stringRef = (__bridge CFStringRef)textToDraw;
// Prepare the text using a Core Text Framesetter
CFAttributedStringRef currentText = CFAttributedStringCreate(NULL, stringRef, NULL);
CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString(currentText);
CGRect frameRect = CGRectMake(0, 0, 300, 50);
CGMutablePathRef framePath = CGPathCreateMutable();
CGPathAddRect(framePath, NULL, frameRect);
// Get the frame that will do the rendering.
CFRange currentRange = CFRangeMake(0, 0);
CTFrameRef frameRef = CTFramesetterCreateFrame(framesetter, currentRange, framePath, NULL);
CGPathRelease(framePath);
// Get the graphics context.
CGContextRef currentContext = UIGraphicsGetCurrentContext();
// Put the text matrix into a known state. This ensures
// that no old scaling factors are left in place.
CGContextSetTextMatrix(currentContext, CGAffineTransformIdentity);
// Core Text draws from the bottom-left corner up, so flip
// the current transform prior to drawing.
CGContextTranslateCTM(currentContext, 0, 100);
CGContextScaleCTM(currentContext, 1.0, -1.0);
// Draw the frame.
CTFrameDraw(frameRef, currentContext);
CFRelease(frameRef);
CFRelease(stringRef);
CFRelease(framesetter);
}
+(void)drawPDF:(NSString*)fileName
{
// Create the PDF context using the default page size of 612 x 792.
UIGraphicsBeginPDFContextToFile(fileName, CGRectZero, nil);
// Mark the beginning of a new page.
UIGraphicsBeginPDFPageWithInfo(CGRectMake(0, 0, 612, 792), nil);
CGPoint from = CGPointMake(0, 0);
CGPoint to = CGPointMake(200, 300);
;
;
// Close the PDF context and write the contents out.
UIGraphicsEndPDFContext();
}
</code></pre></p>
<p style="font-size: 20px;">关于ios - 在 WebView 中生成 PDF 时，如何首先将 PDF 数据写入文件，我们在Stack Overflow上找到一个类似的问题：
<a href="https://stackoverflow.com/questions/16416206/" rel="noreferrer noopener nofollow" style="color: red;">
https://stackoverflow.com/questions/16416206/
</a>
</p>
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