摘要：
最近，一位朋友想要制作pdf预览，这需要能够使用缩放和目录跳转功能上下滚动。因为我以前只做过一个简单的预览，它是直接用uiwebview实现的。这一次，我通过查找信息找到了一个好图书馆。但是，这个库会从左向右翻页。我不习惯。相反，我上下滑动页面，并在底部添加页码。
最近有个朋友想做一个pdf预览，要求能够上下滑动翻页、带缩放、目录跳转功能。
因为之前我只做过简单的预览，那时直接用uiwebview实现的，这次找了下资料，发现一个比较好的库。
其原理实现：
自定义uiview来显示pdf+使用的是苹果官方的api读取目录+uiscrollview实现缩放及翻页。
不过这个库是左右翻页的，我不是很习惯，就改成了上下滑动翻页，并且在底部添加了页码显示（1/10格式）。
效果图如下：
其中几段核心代码：
1、加载pdf文件
CFURLRef pdfURL = CFBundleCopyResourceURL(CFBundleGetMainBundle(), (__bridge CFStringRef)@"002.pdf", NULL, NULL); pdfDocument =CGPDFDocumentCreateWithURL((CFURLRef)pdfURL); CFRelease(pdfURL);
2、获取pdf文件目录
#pragma mark 获取pdf文件目录 - (NSArray *)getPDFContents: (CGPDFDocumentRef) myDocument { CGPDFDictionaryRef mycatalog=CGPDFDocumentGetCatalog(myDocument); CommentNode *rootNode =[[CommentNode alloc] initWithCatalog:mycatalog]; CommentNode *rootOutlineNode = [rootNode childrenForName:@"/Outlines"]; CommentNode *pagesNode = [rootNode childrenForName:@"/Pages"]; NSArray *pagesArray =[self getPagesFromPagesNode:pagesNode]; CommentNode *destsNode = [rootNode childrenForName:@"/Dests"]; return[self getContentsForOutlineNode:rootOutlineNode pages:pagesArray destsNode:destsNode]; } - (NSArray *)getContentsForOutlineNode:(CommentNode *)rootOutlineNode pages:(NSArray *)pagesArray destsNode:(CommentNode *)destsNode { NSMutableArray *outlineArray =[[NSMutableArray alloc] init]; CommentNode *firstOutlineNode = [rootOutlineNode childrenForName:@"/First"]; CommentNode *outlineNode =firstOutlineNode; while(outlineNode) { NSString *title = [[outlineNode childrenForName:@"/Title"] value]; CommentNode *destNode = [outlineNode childrenForName:@"/Dest"]; NSMutableDictionary *outline = [NSMutableDictionary dictionaryWithDictionary:@{@"Title": title}]; int index = 0; if(destNode) { if ([[destNode typeAsString] isEqualToString:@"Array"]) { CGPDFObjectRef dest = (__bridge CGPDFObjectRef)[[[destNode children] objectAtIndex:0] object]; index =[self getIndexInPages:pagesArray forPage:dest]; } else if ([[destNode typeAsString] isEqualToString:@"Name"]) { NSString *destName =[destNode value]; CGPDFObjectRef dest = (__bridge CGPDFObjectRef)[[[[[destsNode childrenForName:destName] childrenForName:@"/D"] children] objectAtIndex:0] object]; index =[self getIndexInPages:pagesArray forPage:dest]; } } else{ CommentNode *aNode = [outlineNode childrenForName:@"/A"]; if(aNode) { CommentNode *dNode = [aNode childrenForName:@"/D"]; if(dNode) { CommentNode *d0Node = [[dNode children] objectAtIndex:0]; if ([[d0Node typeAsString] isEqualToString:@"Dictionary"]) { CGPDFObjectRef dest = (CGPDFObjectRef)[d0Node object]; index =[self getIndexInPages:pagesArray forPage:dest]; } } } } [outline setObject:@(index) forKey:@"Index"]; NSArray *subOutlines =[self getContentsForOutlineNode:outlineNode pages:pagesArray destsNode:destsNode]; [outline setObject:subOutlines forKey:@"SubContents"]; [outlineArray addObject:outline]; outlineNode = [outlineNode childrenForName:@"/Next"]; } returnoutlineArray; } - (NSArray *)getPagesFromPagesNode:(CommentNode *)pagesNode { NSMutableArray *pages = [NSMutableArray new]; CommentNode *kidsNode = [pagesNode childrenForName:@"/Kids"]; for (CommentNode *node in[kidsNode children]) { NSString *type = [[node childrenForName:@"/Type"] value]; if ([type isEqualToString:@"/Pages"]) { NSArray *kidsPages =[self getPagesFromPagesNode:node]; [pages addObjectsFromArray:kidsPages]; } else{ [pages addObject:node]; } } returnpages; } - (int)getIndexInPages:(NSArray *)pages forPage:(CGPDFObjectRef)page { for (int k = 0; k < pages.count; k++) { CommentNode *node =[pages objectAtIndex:k]; if ([node object] ==page) return k+1; } return 1; }
源码获取：https://github.com/TangledHusky/YJ-PDFReader/tree/master
特别鸣谢：
参考文献：https://blog.csdn.net/shenshucong520/article/details/51578695