iOS 使用使用UIDocumentInteractionController预览文件(支持PDF、word、Excel、图片等)

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前言

应公司需求，在项目中需要加入文件预览功能，网上搜说了一下，发现苹果iOS本身有自己的文件预览的API，那就简单多了。
查看APi之后，我们发现UIDocumentInteractionController是个很特别的控制器，它不是继承UIViewController的，而是直接继承NSobject的。还有通过查看它的属性和代理方法，提供一个菜单提供一个菜单，允许用户快速查看、打开或复制文件指定的项目，自动确定正确的应用程序或应用程序，原文如下：

// Presents a menu allowing the user to Quick Look, open, or copy the item specified by URL.
// This automatically determines the correct application or applications that can open the item at URL.
// Returns NO if the options menu contained no options and was not opened.
// Note that you must implement the delegate method documentInteractionControllerViewControllerForPreview: to get the Quick Look menu item.

下面是实现代码:

#import "ViewController.h"

@interface ViewController ()<UIDocumentInteractionControllerDelegate>
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.navigationItem.title=@"预览";

    NSString *urlStr = [[NSBundle mainBundle] pathForResource:@"iOS开发指南.pdf" ofType:nil];
    NSURL *url = [NSURL fileURLWithPath:urlStr];

    UIDocumentInteractionController *documentVc = [UIDocumentInteractionController interactionControllerWithURL:url];
    documentVc.delegate = self;

    [documentVc presentPreviewAnimated:YES];

}

#pragma mark - UIDocumentInteractionController 代理方法
- (UIViewController *)documentInteractionControllerViewControllerForPreview:(UIDocumentInteractionController *)controller{
    return self;
}

- (UIView *)documentInteractionControllerViewForPreview:(UIDocumentInteractionController *)controller{
    return self.view;
}

- (CGRect)documentInteractionControllerRectForPreview:(UIDocumentInteractionController *)controller{
    return self.view.bounds;
}

这三个代理的使用告诉DocumentInteraction Controller如何显示。显示在哪里，和显示的大小
documentInteractionControllerViewControllerForPreview回调控制器
documentInteractionControllerViewForPreview回调View
documentInteractionControllerRectForPreview视图