iOS本地预览和网络预览PDF等文件(四)——QLPreview

项目知识点

• Bundle包的制作与使用
• PDF等文件缓存在沙盒(cache)
• UIDocumentInteractionController本地查看及第三方分享
• QLPreviewController本地预览及网络预预览
  Demo地址
  注:UIDocumentInteractionController和QLPreviewController都能实现文件的本地查看，笔者在立题的时候对QLPreviewController的网络预览有误解，其实两者本质都是将文件缓存到本地进行查看

区别：

1.UIDocumentInteractionController一次只能浏览一个文件，QLPreviewController可以一起浏览多个文件；2.UIDocumentInteractionController有第三方分享和特定操作，QLPreviewController则没有

QLPreviewController本地预览

1.导入QuickLook

#import <QuickLook/QuickLook.h>

2.定义QLPreviewController全局变量且引用数据源代理

@interface FileReviewController () <QLPreviewControllerDataSource>
@property (nonatomic, strong) QLPreviewController *QLController;
@property (nonatomic, copy) NSURL *fileURL;
@end

self.QLController = [[QLPreviewController alloc] init];
self.QLController.dataSource = self;

3.实现QLPreviewController数据源代理

/// 文件路径
- (id<QLPreviewItem>)previewController:(QLPreviewController *)controller previewItemAtIndex:(NSInteger)index {
    return self.fileURL;
}

/// 文件数
- (NSInteger)numberOfPreviewItemsInPreviewController:(QLPreviewController *)controller {
    return 1;
}

4.点击事件

- (void)actionLocal {
    self.fileURL = [[NSBundle mainBundle] URLForResource:@"Jobs" withExtension:@"pdf" subdirectory:@"PDF.bundle"];
    [self presentViewController:self.QLController animated:YES completion:nil];
}

QLPreviewController网络预览

本质是缓存资源到本地然后查看

1.导入AFNetworking

2.点击事件

- (void)actionQLView {
    NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
    
    AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:configuration];
    NSString *urlStr = @"https://www.tutorialspoint.com/ios/ios_tutorial.pdf";
    NSString *fileName = [urlStr lastPathComponent]; //获取文件名称
    NSURL *URL = [NSURL URLWithString:urlStr];
    NSURLRequest *request = [NSURLRequest requestWithURL:URL];
    
    //判断是否存在
    if ([self isFileExist:fileName]) {
        NSURL *documentsDirectoryURL = [[NSFileManager defaultManager] URLForDirectory:NSDocumentDirectory inDomain:NSUserDomainMask appropriateForURL:nil create:NO error:nil];
        NSURL *url = [documentsDirectoryURL URLByAppendingPathComponent:fileName];
        self.fileURL = url;
        [self presentViewController:self.QLController animated:YES completion:nil];
        //刷新界面,如果不刷新的话，不重新走一遍代理方法，返回的url还是上一次的url
        [self.QLController refreshCurrentPreviewItem];
    } else {
        NSURLSessionDownloadTask *downloadTask = [manager downloadTaskWithRequest:request progress:^(NSProgress *downloadProgress){
            
        } destination:^NSURL *(NSURL *targetPath, NSURLResponse *response) {
            NSURL *documentsDirectoryURL = [[NSFileManager defaultManager] URLForDirectory:NSDocumentDirectory inDomain:NSUserDomainMask appropriateForURL:nil create:NO error:nil];
            NSURL *url = [documentsDirectoryURL URLByAppendingPathComponent:fileName];
            return url;
        } completionHandler:^(NSURLResponse *response, NSURL *filePath, NSError *error) {
            self.fileURL = filePath;
            [self presentViewController:self.QLController animated:YES completion:nil];
            //刷新界面,如果不刷新的话，不重新走一遍代理方法，返回的url还是上一次的url
            [self.QLController refreshCurrentPreviewItem];
        }];
        [downloadTask resume];
    }
}

/**
 判断文件是否已经在沙盒中存在

 @param fileName 文件名
 @return 1:存在 0:不存在
 */
- (BOOL)isFileExist:(NSString *)fileName
{
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *path = [paths objectAtIndex:0];
    NSString *filePath = [path stringByAppendingPathComponent:fileName];
    NSFileManager *fileManager = [NSFileManager defaultManager];
    BOOL result = [fileManager fileExistsAtPath:filePath];
    return result;
}

QLPreviewController预览多个文件

只需要改变QLPreviewControllerDataSource，使用方法跟UITableviewDataSource类似

#pragma mark - QLPreviewControllerDataSource
- (id<QLPreviewItem>)previewController:(QLPreviewController *)controller previewItemAtIndex:(NSInteger)index {
    if (index == 0) {
        return [[NSBundle mainBundle] URLForResource:@"image" withExtension:@"png" subdirectory:@"PDF.bundle"];
    } else {
        return self.fileURL;
    }
}

- (NSInteger)numberOfPreviewItemsInPreviewController:(QLPreviewController *)controller {
    return 2;
}

预览多文件

展示页可以左右滑动切换文件预览，也可以点击右下方按钮跳转到文件选择页

文件选择图