Try this code..It adds up 1st pdf file then at the of that it,it adds 2nd pdf file to make single pdf.
NSString *cacheDir = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];
// File paths
NSString *pdfPath1 = [[NSBundle mainBundle] pathForResource:@"pdf1" ofType:@"pdf"];
NSString *pdfPath2 = [cacheDir stringByAppendingPathComponent:@"temp.pdf"];
NSString *pdfPathOutput = [cacheDir stringByAppendingPathComponent:@"out.pdf"];
// File URLs - bridge casting for ARC
CFURLRef pdfURL1 = (__bridge_retained CFURLRef)[[NSURL alloc] initFileURLWithPath:(NSString *)pdfPath1];//(CFURLRef) NSURL
CFURLRef pdfURL2 = (__bridge_retained CFURLRef)[[NSURL alloc] initFileURLWithPath:(NSString *)pdfPath2];//(CFURLRef)
CFURLRef pdfURLOutput =(__bridge_retained CFURLRef) [[NSURL alloc] initFileURLWithPath:(NSString *)pdfPathOutput];//(CFURLRef)
// File references
CGPDFDocumentRef pdfRef1 = CGPDFDocumentCreateWithURL((CFURLRef) pdfURL1);
CGPDFDocumentRef pdfRef2 = CGPDFDocumentCreateWithURL((CFURLRef) pdfURL2);
// Number of pages
NSInteger numberOfPages1 = CGPDFDocumentGetNumberOfPages(pdfRef1);
NSInteger numberOfPages2 = CGPDFDocumentGetNumberOfPages(pdfRef2);
// Create the output context
CGContextRef writeContext = CGPDFContextCreateWithURL(pdfURLOutput, NULL, NULL);
// Loop variables
CGPDFPageRef page;
CGRect mediaBox;
// Read the first PDF and generate the output pages
NSLog(@"GENERATING PAGES FROM PDF 1 (%i)...", numberOfPages1);
for (int i=1; i<=numberOfPages1; i++) {
page = CGPDFDocumentGetPage(pdfRef1, i);
mediaBox = CGPDFPageGetBoxRect(page, kCGPDFMediaBox);
CGContextBeginPage(writeContext, &mediaBox);
CGContextDrawPDFPage(writeContext, page);
CGContextEndPage(writeContext);
}
// Read the second PDF and generate the output pages
NSLog(@"GENERATING PAGES FROM PDF 2 (%i)...", numberOfPages2);
for (int i=1; i<=numberOfPages2; i++) {
page = CGPDFDocumentGetPage(pdfRef2, i);
mediaBox = CGPDFPageGetBoxRect(page, kCGPDFMediaBox);
CGContextBeginPage(writeContext, &mediaBox);
CGContextDrawPDFPage(writeContext, page);
CGContextEndPage(writeContext);
}
NSLog(@"DONE!");
// Finalize the output file
CGPDFContextClose(writeContext);
// Release from memory
CFRelease(pdfURL1);
CFRelease(pdfURL2);
CFRelease(pdfURLOutput);
CGPDFDocumentRelease(pdfRef1);
CGPDFDocumentRelease(pdfRef2);
CGContextRelease(writeContext);