Ios 创建PDF时内存警告和崩溃

生成大型PDF时，我的应用程序会收到内存警告，然后在生成PDF的过程中崩溃。PDF被绘制到web视图中，当页面超过一定数量（取决于设备）时，我会耗尽内存

到目前为止，我对这件事的研究让我明白，我需要：

将

UIGraphicsBeginPDFContextToData

更改为

IGraphicsBeginPDFContextToFile

创建临时文件的合理路径

把这个给函数

将文件交给webview以加载

完成后删除该文件

问题是，虽然我认为我在原则上掌握了它，但我不知道如何去实现它，或者完全理解它以便在代码中实现它。这件事上的建议很受欢迎

我也愿意接受任何其他方法来阻止内存崩溃

@interface ICPDFPreviewController ()
@property (nonatomic, strong) Certificate *certificate;
@property (nonatomic, strong) NSData *pdfData;
@property (nonatomic) BOOL viewHasUnloaded;
- (void)generatePdf;
- (void)pdfDone:(NSData *)data;
- (NSData *)createPdfWithPages:(NSArray *)pages;
@end

@implementation ICPDFPreviewController
@synthesize certificate=_certificate;
@synthesize scrollView=_scrollView;
@synthesize webView=_webView;
@synthesize pdfData=_pdfData;
@synthesize viewHasUnloaded=_viewHasUnloaded;



- (void)generatePdf
 {
 NSMutableArray *pagesArray = [NSMutableArray array];

 if ([self.certificate.certificateType.title isEqualToString:@"Minor Works"]) {
[pagesArray addObject:[[ICPDFMinorWorksPage1 alloc] initWithCertificate:self.certificate]];
 [pagesArray addObject:[[ICPDFMinorWorksPage2 alloc] initWithCertificate:self.certificate]];

 } else if ([self.certificate.certificateType.title isEqualToString:@"EIC"]) {
[pagesArray addObject:[[ICPDFEICPage1 alloc] initWithCertificate:self.certificate]];
[pagesArray addObject:[[ICPDFEICPage2 alloc] initWithCertificate:self.certificate]];
[pagesArray addObject:[[ICPDFEICPage3 alloc] initWithCertificate:self.certificate]];
[pagesArray addObject:[[ICPDFEICPage4 alloc] initWithCertificate:self.certificate]];
[pagesArray addObject:[[ICPDFEICPage5 alloc] initWithCertificate:self.certificate]];
[self addDistributionBoardsToPagesArray:pagesArray];
ICPDFEICPageFinal *pageFinal = [[ICPDFEICPageFinal alloc]        initWithCertificate:self.certificate];
 pageFinal.pageNumber.text = [NSString stringWithFormat:@"%d", pagesArray.count+1];
[pagesArray addObject:pageFinal];

} else if ([self.certificate.certificateType.title isEqualToString:@"Domestic EIC"]) {
[pagesArray addObject:[[ICPDFDomesticEICPage1 alloc] initWithCertificate:self.certificate]];
[pagesArray addObject:[[ICPDFDomesticEICPage2 alloc] initWithCertificate:self.certificate]];
[pagesArray addObject:[[ICPDFDomesticEICPage3 alloc] initWithCertificate:self.certificate]];
[pagesArray addObject:[[ICPDFDomesticEICPage4 alloc] initWithCertificate:self.certificate]];
[self addDistributionBoardsToPagesArray:pagesArray];
[pagesArray addObject:[[ICPDFDomesticEICPageFinal alloc] initWithCertificate:self.certificate]];

} else if ([self.certificate.certificateType.title isEqualToString:@"EICR"]) {
[pagesArray addObject:[[ICPDFEICRPage1 alloc] initWithCertificate:self.certificate]];
[pagesArray addObject:[[ICPDFEICRPage2 alloc] initWithCertificate:self.certificate]];
[self addObservationsToPagesArray:pagesArray];
[self addDistributionBoardsToPagesArray:pagesArray];
[pagesArray addObject:[[ICPDFEICRInspection alloc] initWithCertificate:self.certificate]];
[pagesArray addObject:[[ICPDFEICRInspectionPage1 alloc] initWithCertificate:self.certificate]];
[pagesArray addObject:[[ICPDFEICRInspectionPage2 alloc] initWithCertificate:self.certificate]];
[pagesArray addObject:[[ICPDFEICRInspectionPage3 alloc] initWithCertificate:self.certificate]];
[pagesArray addObject:[[ICPDFEICRPageFinal alloc] initWithCertificate:self.certificate]];
 }

// Set page count on all pages
int pageNumber = 0;
for (ICCertificateComponent *page in pagesArray) {
page.pageNumber.text = [NSString stringWithFormat:@"%d", ++pageNumber];
page.pageCount.text = [NSString stringWithFormat:@"%d", pagesArray.count];
}

 NSData *pdfData = [self createPdfWithPages:pagesArray];
[self performSelectorOnMainThread:@selector(pdfDone:) withObject:pdfData waitUntilDone:YES];

 }

- (void)pdfDone:(NSData *)data
 {
 self.pdfData = data;
[self.webView loadData:self.pdfData MIMEType:@"application/pdf" textEncodingName:@"utf-8"      baseURL:nil];
 [ICUtils removeProgressView];
 }

 - (NSData *)createPdfWithPages:(NSArray *)pages
  {
 // Creates a mutable data object for updating with binary data, like a byte array
 NSMutableData *pdfData = [NSMutableData data];

 ICCertificateComponent *firstPage = [pages objectAtIndex:0];

UIGraphicsBeginPDFContextToData(pdfData, firstPage.contentView.bounds, nil);

 for (int i = 0; i < pages.count; i++) {
 ICCertificateComponent *thisPage = [pages objectAtIndex:i];
 UIGraphicsBeginPDFPageWithInfo(thisPage.contentView.bounds, nil);


 CGContextRef pdfContext = UIGraphicsGetCurrentContext();
 [thisPage.contentView.layer renderInContext:pdfContext];
 }

 UIGraphicsEndPDFContext();

 return pdfData;
}

- (void)addDistributionBoardsToPagesArray:(NSMutableArray *)pagesArray
{
int pageCount = pagesArray.count;
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"createdAt"       ascending:YES];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil]; 
NSArray *boards = [self.certificate.distributionBoards      sortedArrayUsingDescriptors:sortDescriptors];
 for (DistributionBoard *thisBoard in boards) {
DebugLog(@"Creating a board page");
ICPDFDistributionBoard *boardPage = [[ICPDFDistributionBoard alloc]        initWithDistributionBoard:thisBoard];
boardPage.pageNumber.text = [NSString stringWithFormat:@"%d", ++pageCount];
DebugLog(@"Page number is %d", pageCount);
[pagesArray addObject:boardPage];

NSSortDescriptor *circuitDescriptor = [[NSSortDescriptor alloc] initWithKey:@"createdAt"     ascending:YES];
NSArray *circuitDescriptors = [[NSArray alloc] initWithObjects:circuitDescriptor, nil]; 
NSArray *circuits = [thisBoard.circuits sortedArrayUsingDescriptors:circuitDescriptors];

 //int circuitCount = circuits.count;
 ICPDFCircuitDetails *circuitDetails = boardPage.circuitDetails;

int circuitCount = 0;
for (Circuit *thisCircuit in circuits) {
circuitCount++;
if (circuitCount > 16) {
    // Add an extension page
    DebugLog(@"Adding an extension sheet");
    circuitCount = 1;
    ICPDFDistributionBoardExtension *boardExtension = [[ICPDFDistributionBoardExtension  alloc]   initWithDistributionBoard:thisBoard];
    [pagesArray addObject:boardExtension];
    boardExtension.pageNumber.text = [NSString stringWithFormat:@"%d", ++pageCount];
    circuitDetails = boardExtension.circuitDetails;
   }
    NSString *key = [NSString stringWithFormat:@"circuitRow%d", circuitCount];
   ICCircuitRow *circuitRow = [circuitDetails valueForKey:key];
   [circuitRow populateFromCircuit:thisCircuit];
  }
 }
}

@接口ICPDFPreviewController（）
@属性（非原子、强）证书*证书；
@属性（非原子，强）NSData*pdfData；
@属性（非原子）BOOL viewHasUnload；
-（无效）生成EPDF；
-（无效）pdfDone:（NSData*）数据；
-（NSData*）createPdfWithPages:（NSArray*）页；
@结束
@ICPDFPreviewController的实现
@综合证书=_证书；
@综合滚动视图=_滚动视图；
@综合网络视图=_网络视图；
@合成pdfData=_pdfData；
@综合ViewHasUnload=\u ViewHasUnload；
-（无效）生成EPDF
{
NSMutableArray*页面数组=[NSMutableArray]；
如果（[self.certificate.certificateType.title isEqualToString:@“次要工程”]）{
[pagesArray addObject:[[ICPDFMinorWorksPage1 alloc]initWithCertificate:self.certificate]]；
[pagesArray addObject:[[ICPDFMinorWorksPage2 alloc]initWithCertificate:self.certificate]]；
}else if（[self.certificate.certificateType.title IsequalString:@“EIC”]）{
[pagesArray addObject:[[ICPDFEICPage1 alloc]initWithCertificate:self.certificate]]；
[pagesArray addObject:[[ICPDFEICPage2 alloc]initWithCertificate:self.certificate]]；
[pagesArray addObject:[[ICPDFEICPage3 alloc]initWithCertificate:self.certificate]]；
[pagesArray addObject:[[ICPDFEICPage4 alloc]initWithCertificate:self.certificate]]；
[pagesArray addObject:[[ICPDFEICPage5 alloc]initWithCertificate:self.certificate]]；
[self-addDistributionBoardsToPagesArray:pagesArray]；
ICPDFEICPageFinal*pageFinal=[[ICPDFEICPageFinal alloc]initWithCertificate:self.certificate]；
pageFinal.pageNumber.text=[NSString stringWithFormat:@“%d”，pagesArray.count+1]；
[pagesArray addObject:pageFinal]；
}else if（[self.certificate.certificateType.title IsequalString:@“国内EIC”]）{
[pagesArray addObject:[[ICPDFDomesticEICPage1 alloc]initWithCertificate:self.certificate]；
[pagesArray addObject:[[ICPDFDomesticEICPage2 alloc]initWithCertificate:self.certificate]；
[pagesArray addObject:[[ICPDFDomesticEICPage3 alloc]initWithCertificate:self.certificate]；
[pagesArray addObject:[[ICPDFDomesticEICPage4 alloc]initWithCertificate:self.certificate]；
[self-addDistributionBoardsToPagesArray:pagesArray]；
[pagesArray addObject:[[ICPDFDomesticEICPageFinal alloc]initWithCertificate:self.certificate]]；
}else if（[self.certificate.certificateType.title IsequalString:@“EICR”]）{
[pagesArray addObject:[[ICPDFEICRPage1 alloc]initWithCertificate:self.certificate]]；
[pagesArray addObject:[[ICPDFEICRPage2 alloc]initWithCertificate:self.certificate]]；
[自助添加ObservationsTopageSarray:pagesArray]；
[self-addDistributionBoardsToPagesArray:pagesArray]；
[pagesArray addObject:[[ICPDFEICRInspection alloc]initWithCertificate:self.certificate]]；
[pagesArray addObject:[[ICPDFEICInspectionPage1 alloc]initWithCertificate:self.certificate]]；
[pagesArray addObject:[[ICPDFEICInspectionPage2 alloc]initWithCertificate:self.certificate]]；
[pagesArray addObject:[[ICPDFEICInspectionPage3 alloc]initWithCertificate:self.certificate]]；
[pagesArray addObject:[[ICPDFEICRPageFinal alloc]initWithCertificate:self.certificate]]；
}
//设置所有页面的页数
int pageNumber=0；
用于（ICCertificateComponent*第页中的第页）{
page.pageNumber.text=[NSString stringWithFormat:@“%d”，++pageNumber]；
page.pageCount.text=[NSString stringWithFormat:@“%d”，pagesArray.count]；
}
NSData*pdfData=[self-createPdfWithPages:pagesArray]；
[self-performSelectorOnMainThread:@selector（pdfDone:）with object:pdfData waituntldone:YES]；
}
-（无效）pdfDone:（NSData*）数据
{
self.pdfData=数据；
[self.webView加载数据：self.pdfData MIMEType:@“application/pdf”text编码名称：@“utf-8”baseURL:nil]；
[ICUtils removeProgressView]；
}
-（NSData*）createPdfWithPages:（NSArray*）页面
{
//创建一个可变数据对象，以便使用二进制数据（如字节数组）进行更新
NSMutableData*pdfData=[NSMutableData]；
ICCertificateComponent*firstPage=[页面对象索引：0]；
UIGraphicsBeginPDFContextToData（pdfData，firstPage.contentView.bounds，nil）；
对于（int i=0；i 2013-02-08 10:38:35.475 iCertifi[5772:907] Received memory warning.
 2013-02-08 10:38:35.477 iCertifi[5772:907] <ICPDFPreviewController: 0x1eb28930>   didReceiveMemoryWarning

// start pdf document using default page size (CGRectZero)
UIGraphicsBeginPDFContextToFile(pdfFileName, CGRectZero, nil); 

// then loop through your content drawing it one page at a time.
for ( page p in pages )   // or whatever you are cycling over for page content
{
   UIGraphicsBeginPDFPage();   // or UIGraphicsBeginPDFPageWithInfo

  // do your drawing to the page here by drawing to the current graphics context.
  // if you are setting up transforms and such

}
// close out the last page and the document both
UIGraphicsEndPDFContext();

- (IBAction)buttonPress:(id)sender
{
    [self createPDFData:[self getPDFFileName]];
}
-(NSString *)getPDFFileName
{
    NSString * fileName = @"Info.PDF";

    NSArray *arrayPaths =
    NSSearchPathForDirectoriesInDomains(
                                        NSDocumentDirectory,
                                        NSUserDomainMask,
                                        YES);
    NSString * path = [arrayPaths objectAtIndex:0];
    NSString *pdfFileName = [path stringByAppendingPathComponent:fileName];
    NSLog(@"path : %@",path);
    NSLog(@"pdf file name : %@",pdfFileName);
    return pdfFileName;

}

-(void)showPDFFile
{


    UIWebView *  webView = [[UIWebView alloc] initWithFrame:CGRectMake(0,44,1024,748)];

    NSURL *url = [NSURL fileURLWithPath:[self getPDFFileName]];
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    [webView setScalesPageToFit:YES];
    [webView loadRequest:request];

    [self.view addSubview:webView];

}


-(void)createPDFData:(NSString *)fileName{

    CGRect pageFrame = CGRectMake(0,0,768,1024);
    UIGraphicsBeginPDFContextToFile(fileName, CGRectZero, nil);//This starts drawing a pdf to file named "filename"  UIGraphicsBeginPDFPageWithInfo(pageFrame, nil);//For each new page call this
    UIGraphicsGetCurrentContext();
    UIGraphicsBeginPDFPageWithInfo(pageFrame, nil);//Next or new Page
    NSString * timeLabel = [NSString stringWithFormat:@"Some text"];
    [timeLabel drawInRect:CGRectMake(200, 200, 428, 44) withFont:[UIFont boldSystemFontOfSize:10] lineBreakMode:NSLineBreakByWordWrapping alignment:NSTextAlignmentLeft];
    UIGraphicsEndPDFContext();
    [self showPDFFile];
}

for (int i = 0; i < pages.count; i++) {

// notice this line 
     @autureleasepool 
     {
       ICCertificateComponent *thisPage = [pages objectAtIndex:i];
       UIGraphicsBeginPDFPageWithInfo(thisPage.contentView.bounds, nil);


       CGContextRef pdfContext = UIGraphicsGetCurrentContext();
       [thisPage.contentView.layer renderInContext:pdfContext];
     }
 }

...
    CGPoint savedContentOffset;
    CGRect savedFrame;
    NSMutableData * pdfData;
    int pdfOffset;
    NSTimer *timer;
...

- (void)preparePdf {
    CGFloat height = aWebView.scrollView.contentSize.height;
    CGRect screenRect = [[UIScreen mainScreen] bounds];
    int pageHeight = screenRect.size.height;

    savedContentOffset = aWebView.scrollView.contentOffset;
    savedFrame = aWebView.frame;
    pdfData=[NSMutableData data];

    aWebView.scrollView.contentOffset = CGPointZero;
    aWebView.frame = CGRectMake(aWebView.frame.origin.x,aWebView.frame.origin.y,aWebView.frame.size.width,pageHeight);

    UIGraphicsBeginPDFContextToData(pdfData, aWebView.frame, nil);

    NSLog(@"pageHeight = %d", pageHeight);
    pdfOffset = 0;

    timer = [NSTimer scheduledTimerWithTimeInterval: 0.4
                                             target: self
                                           selector: @selector(printPdfPage:)
                                           userInfo: nil
                                            repeats: YES];
}

- (void) printPdfPage: (NSTimer*) timer {
    CGFloat height = aWebView.scrollView.contentSize.height;
    CGRect screenRect = [[UIScreen mainScreen] bounds];
    int pageHeight = screenRect.size.height;

    NSLog(@"pdfOffset = %d", pdfOffset);
    UIGraphicsBeginPDFPage();
    [aWebView drawViewHierarchyInRect:CGRectMake(0, 0, screenRect.size.width, pageHeight) afterScreenUpdates:YES];

    pdfOffset += pageHeight;
    aWebView.scrollView.contentOffset = CGPointMake(0, pdfOffset);

    if (pdfOffset > height) {
        [timer invalidate];
        NSLog(@"pdf data size: %ld", pdfData.length);
        [self emailPdf: pdfData];
    }
}

- (void) emailPdf: (NSMutableData*) pdfData {

    // finally end the PDF context.
    UIGraphicsEndPDFContext();

    aWebView.scrollView.contentOffset = savedContentOffset;
    aWebView.frame = savedFrame;

    MFMailComposeViewController *mailer = [[MFMailComposeViewController alloc] init];
    mailer.mailComposeDelegate = self;
    [mailer setSubject:[@"iPad Screenshot " stringByAppendingString:[self getDate]]];
    [mailer addAttachmentData:pdfData mimeType:@"application/pdf" fileName:[[self getDate] stringByAppendingPathExtension:@"pdf"]];
    NSString *emailBody = @"";
    [mailer setMessageBody:emailBody isHTML:NO];
    [self presentViewController:mailer animated:YES completion:nil];

    if ([SVProgressHUD isVisible]) {
        [SVProgressHUD showSuccessWithStatus:@"Screenshot prepared."];
    }
    pdfData = nil;
    timer = nil;
}