iOS实现PDF文件浏览功能

写了一个小Demo，显示本地PDF格式文件，支持翻页、跳页、缩放。

先看一下效果图：

iOS开发，显示PDF格式文件方法有很多：

• 最简单的应该是UIWebView，可以加载本地或网络PDF文件，支持上下滑动浏览、缩放。
• 优化一点的是用系统的QLPreviewController加载，实现起来也比较方便，支持上下滑动浏览，左后滑动可多PDF文件切换，同时支持原生的分享打印，QLPreviewController支持的文档格式也比较多，如pdf、doc、docx、xls、xlsx、txt、ppt、mp4...
• 上面两种都没有足够的自定义空间，不在这里做过多的介绍了，另外一种也就是本篇用到的iOS核心图形库：Core Graphics，绘制PDF文档。

简单说一下逻辑，根据本地路径获取到CGPDFDocumentRef，在drawRect中绘制上下文，画出PDF文件。通过UIScrollView实现缩放，添加UIGestureRecognizer实现单击、双击、左滑、右滑功能。基于CATransition实现翻页动画。

下面贴上核心代码：

承载PDF文件视图的控制器：HWPDFBrowseVC

#import <UIKit/UIKit.h>

@interface HWPDFBrowseVC : UIViewController

@property (nonatomic,copy) NSString *filePath;
@property (nonatomic,copy) NSString *fileName;

@end

/*** ---------------分割线--------------- ***/

#import "HWPDFBrowseVC.h"
#import "HWPDFBrowseView.h"
#import "HWPDFBrowseToolBar.h"
#import "HWPDFBrowseScrollView.h"

#define KPicMaxScale 3.0
#define KMainW [UIScreen mainScreen].bounds.size.width
#define KMainH [UIScreen mainScreen].bounds.size.height

@interface HWPDFBrowseVC ()<UIScrollViewDelegate,HWPDFBroeseToolBarDelegate>

@property (nonatomic,weak) HWPDFBrowseScrollView *scrollView;
@property (nonatomic,weak) HWPDFBrowseView *browseView;
@property (nonatomic,weak) HWPDFBrowseToolBar *toolBar;
@property (nonatomic,assign) CGFloat minZoomScale;
@property (nonatomic,assign) CGFloat lastScrContX;

@end

@implementation HWPDFBrowseVC

- (void)viewDidLoad {
 [super viewDidLoad];

 //初始化
 self.view.backgroundColor = [UIColor whiteColor];
 self.navigationItem.title = _fileName;

 //创建控件
 [self creatControl];
}

- (void)viewWillDisappear:(BOOL)animated
{
 [super viewWillDisappear:animated];

 //防止隐藏导航时，左滑返回导航消失
 CGRect temNavBarFrame = self.navigationController.navigationBar.frame;
 temNavBarFrame.origin.y = 20;
 self.navigationController.navigationBar.frame = temNavBarFrame;
}

- (void)creatControl
{
 //导航右侧按钮
 UIButton *deleteBtn = [[UIButton alloc] initWithFrame:CGRectMake(9,40,40)];
 deleteBtn.titleLabel.font = [UIFont systemFontOfSize:16.f];
 [deleteBtn setTitle:@"跳页" forState:UIControlStateNormal];
 [deleteBtn setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
 [deleteBtn addTarget:self action:@selector(navBtnOnClick) forControlEvents:UIControlEventTouchUpInside];
 UIView *rightView = [[UIView alloc] initWithFrame:CGRectMake(0,40)];
 [rightView addSubview:deleteBtn];
 self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:rightView];

 //scrollView
 HWPDFBrowseScrollView *scrollView = [[HWPDFBrowseScrollView alloc] initWithFrame:[UIScreen mainScreen].bounds];
 scrollView.delegate = self;
 scrollView.backgroundColor = [UIColor blackColor];
 scrollView.maximumZoomScale = KPicMaxScale;
 scrollView.showsVerticalScrollIndicator = NO;
 scrollView.showsHorizontalScrollIndicator = NO;
 [self.view addSubview:scrollView];
 _scrollView = scrollView;

 //pdf视图
 HWPDFBrowseView *browseView = [[HWPDFBrowseView alloc] initWithFilePath:_filePath];
 [scrollView addSubview:browseView];
 _browseView = browseView;

 //绘制pdf视图后缩放至屏幕完全居中显示
 CGRect frame = browseView.frame;
 frame.size.width = browseView.frame.size.width > KMainW ? KMainW : browseView.frame.size.width;
 frame.size.height = frame.size.width * (browseView.frame.size.height / browseView.frame.size.width);
 if (frame.size.height > KMainH) {
 frame.size.height = KMainH;
 frame.size.width = KMainH * (browseView.frame.size.width / browseView.frame.size.height);
 }

 //根据缩放调整
 _minZoomScale = frame.size.width / browseView.frame.size.width;
 scrollView.allowScrollScale = _minZoomScale;
 scrollView.minimumZoomScale = _minZoomScale;
 scrollView.zoomScale = _minZoomScale;

 //底部工具栏
 HWPDFBrowseToolBar *toolBar = [[HWPDFBrowseToolBar alloc] initWithFrame:CGRectMake(0,KMainH - 49,KMainW,49) currentPage:_browseView.currentPage totalPage:_browseView.totalPages];
 toolBar.delegate = self;
 [self.view addSubview:toolBar];
 _toolBar = toolBar;

 //单击
 UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(click)];
 tap.numberOfTouchesRequired = 1;
 tap.numberOfTapsRequired = 1;
 [scrollView addGestureRecognizer:tap];

 //双击
 UITapGestureRecognizer *tapDouble = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(doubleClick)];
 tapDouble.numberOfTapsRequired = 2;
 [scrollView addGestureRecognizer:tapDouble];
 [tap requireGestureRecognizerToFail:tapDouble];

 //右滑手势
 UISwipeGestureRecognizer *rightSwip = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(nextPage)];
 rightSwip.direction = UISwipeGestureRecognizerDirectionLeft;
 [scrollView addGestureRecognizer:rightSwip];

 //左滑手势
 UISwipeGestureRecognizer *leftSwip = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(forwardPage)];
 leftSwip.direction = UISwipeGestureRecognizerDirectionRight;
 [scrollView addGestureRecognizer:leftSwip];
}

- (void)navBtnOnClick
{
 [_toolBar showWindow];
}

//单击屏幕显示隐藏菜单
- (void)click
{
 CGFloat navBarY = _toolBar.frame.origin.y == KMainH - 49 ? -64 : 20;
 CGFloat toolBarY = _toolBar.frame.origin.y == KMainH - 49 ? KMainH : KMainH - 49;

 [UIView animateWithDuration:0.25 animations:^{
 CGRect temNavBarFrame = self.navigationController.navigationBar.frame;
 temNavBarFrame.origin.y = navBarY;
 self.navigationController.navigationBar.frame = temNavBarFrame;
 CGRect temToolBarFrame = _toolBar.frame;
 temToolBarFrame.origin.y = toolBarY;
 _toolBar.frame = temToolBarFrame;
 }];
}

//双击屏幕放大缩小图片
- (void)doubleClick
{
 [UIView animateWithDuration:0.25f animations:^{
 _scrollView.zoomScale = _scrollView.zoomScale == _minZoomScale ? KPicMaxScale : _minZoomScale;
 }];
}

//左滑事件
- (void)nextPage
{
 [_browseView nextPage];
 _toolBar.currentPage = _browseView.currentPage;
}

//右滑事件
- (void)forwardPage
{
 [_browseView prePage];
 _toolBar.currentPage = _browseView.currentPage;
}

#pragma mark - UICouseBrowseToolBarDelegate
- (void)browseToolBar:(HWPDFBrowseToolBar *)browseToolBar didClickFinishButtonWithPage:(NSString *)page
{
 _browseView.currentPage = [page integerValue];
 [_browseView reloadView];
 [_toolBar dismissKeyboard];
 _scrollView.zoomScale = _minZoomScale;
}

- (void)browseToolBar:(HWPDFBrowseToolBar *)browseToolBar didPageButtonWithAction:(BOOL)nextPage
{
 if (nextPage) {
 [self nextPage];
 }else {
 [self forwardPage];
 }
 _scrollView.zoomScale = _minZoomScale;
}

#pragma mark - UIScrollViewDelegate
- (void)scrollViewDidZoom:(UIScrollView *)scrollView
{
 CGFloat offsetX = (scrollView.bounds.size.width > scrollView.contentSize.width) ? (scrollView.bounds.size.width - scrollView.contentSize.width) * 0.5 : 0.0;
 CGFloat offsetY = (scrollView.bounds.size.height > scrollView.contentSize.height) ? (scrollView.bounds.size.height - scrollView.contentSize.height) * 0.5 : 0.0;
 _browseView.center = CGPointMake(scrollView.contentSize.width * 0.5 + offsetX,scrollView.contentSize.height * 0.5 + offsetY - 64);
}

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
 return _browseView;
}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
 if (scrollView.isZooming) return;

 //允许翻页的偏移量
 CGFloat movePadding = 70.f;

 //仿苹果原生相册，图片放大后，滑动前在边界时在可以翻页，这里加了±10的偏移量
 if (scrollView.contentOffset.x < - movePadding && _lastScrContX < 10) {
 _scrollView.zoomScale = _minZoomScale;
 [self forwardPage];
 }

 if (scrollView.contentSize.width - scrollView.contentOffset.x < KMainW - movePadding && scrollView.contentSize.width != 0 && fabsf(_lastScrContX + KMainW - scrollView.contentSize.width) < 10) {
 _scrollView.zoomScale = _minZoomScale;
 [self nextPage];
 }
}

//滑动自然停止时调用
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
 _lastScrContX = scrollView.contentOffset.x;
}

//滑动手动停止时调用
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
{
 _lastScrContX = scrollView.contentOffset.x;
}

- (void)didReceiveMemoryWarning {
 [super didReceiveMemoryWarning];
 // Dispose of any resources that can be recreated.
}

@end

PDF文件视图：HWPDFBrowseView

#import <UIKit/UIKit.h>

@interface HWPDFBrowseView : UIView{
 CGPDFDocumentRef pdfDocumentRef;
}

@property (nonatomic,assign) NSInteger currentPage;
@property (nonatomic,assign) NSInteger totalPages;

- (id)initWithFilePath:(NSString *)filePath;
- (void)reloadView;
- (void)prePage;
- (void)nextPage;

@end

/*** ---------------分割线--------------- ***/

#import "HWPDFBrowseView.h"

@implementation HWPDFBrowseView

- (id)initWithFilePath:(NSString *)filePath
{
 pdfDocumentRef = [self createPDFFromExistFile:filePath];

 self = [super initWithFrame:CGPDFPageGetBoxRect(CGPDFDocumentGetPage(pdfDocumentRef,1),kCGPDFMediaBox)];

 return self;
}

- (CGPDFDocumentRef)createPDFFromExistFile:(NSString *)aFilePath
{
 CFStringRef path = CFStringCreateWithCString(NULL,[aFilePath UTF8String],kCFStringEncodingUTF8);
 CFURLRef urlRef = CFURLCreateWithFileSystemPath(NULL,path,kCFURLPOSIXPathStyle,NO);
 CFRelease(path);
 CGPDFDocumentRef document = CGPDFDocumentCreateWithURL(urlRef);
 CFRelease(urlRef);
 _totalPages = CGPDFDocumentGetNumberOfPages(document);
 _currentPage = 1;
 if (_totalPages == 0) return NULL;

 return document;
}

- (void)reloadView
{
 [self setNeedsDisplay];
}

- (void)drawRect:(CGRect)rect
{
 CGContextRef context = UIGraphicsGetCurrentContext();
 [[UIColor whiteColor] set];
 CGContextFillRect(context,rect);
 CGContextTranslateCTM(context,0.0,rect.size.height);
 CGContextScaleCTM(context,1.0,-1.0);
 CGPDFPageRef page = CGPDFDocumentGetPage(pdfDocumentRef,_currentPage);
 CGAffineTransform pdfTransform = CGPDFPageGetDrawingTransform(page,kCGPDFCropBox,rect,true);
 CGContextConcatCTM(context,pdfTransform);
 CGContextDrawPDFPage(context,page);
}

//上一页
- (void)prePage
{
 if(_currentPage < 2) {
 UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"提示" message:@"已经第一页了！" delegate:self cancelButtonTitle:@"确定" otherButtonTitles: nil ];
 [alert show];
 return;
 }

 --_currentPage;
 [self reloadView];
 [self transitionWithType:@"pageUnCurl" WithSubtype:kCATransitionFromRight ForView:self];
}

//下一页
- (void)nextPage
{
 if(_currentPage >= _totalPages) {
 UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"提示" message:@"已经最后一页了！" delegate:self cancelButtonTitle:@"确定" otherButtonTitles: nil ];
 [alert show];
 return;
 }

 ++_currentPage;
 [self reloadView];
 [self transitionWithType:@"pageCurl" WithSubtype:kCATransitionFromRight ForView:self];
}

//设置翻页动画效果
- (void)transitionWithType:(NSString *)type WithSubtype:(NSString *)subtype ForView:(UIView *)view
{
 CATransition *animation = [CATransition animation];
 animation.duration = 0.7f;
 animation.type = type;
 if (subtype) animation.subtype = subtype;
 animation.timingFunction = UIViewAnimationOptionCurveEaseInOut;
 [view.layer addAnimation:animation forKey:@"animation"];
}

@end

Demo 下载链接

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