此类用于改变QLPreviewController 导航栏title

#import <QuickLook/QuickLook.h>

NS_ASSUME_NONNULL_BEGIN

@interface QLPreviewController (title)

@property (nonatomic, strong) NSString *qlpTitle;

@end

NS_ASSUME_NONNULL_END

#import "QLPreviewController+title.h"
#import <objc/runtime.h>

@implementation QLPreviewController (title)

- (void)setQlpTitle:(NSString *)qlpTitle {
    objc_setAssociatedObject(self, @"qlpTitle", qlpTitle, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

- (NSString *)qlpTitle {
    return objc_getAssociatedObject(self, @"qlpTitle");
}

- (void)setTitle:(NSString *)title {
    if (self.qlpTitle) {
        self.navigationItem.title = self.qlpTitle;
    } else {
        self.navigationItem.title = title;
    }
}

@end

预览效果

引入#import <QuickLook/QuickLook.h>

遵循代理 QLPreviewControllerDataSource,QLPreviewControllerDelegate  定义UIWebView *openFileWebView;

点击效果代码

openFileWebView = [[UIWebView alloc]initWithFrame:CGRectMake(0, 64, self.view.frame.size.width, self.view.frame.size.height)];
    openFileWebView.delegate = self;
    [openFileWebView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:self.workDetailsModel.annex]]];

- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType
{
    return YES;
}
#pragma mark - Web代理
- (void)webViewDidFinishLoad:(UIWebView *)webView {
   
        NSURL *targetURL = [NSURL URLWithString:self.workDetailsModel.annex];
        
        NSString *docPath = [self documentsDirectoryPath];
        NSString *pathToDownloadTo = [NSString stringWithFormat:@"%@/%@", docPath, [targetURL lastPathComponent]];
        NSFileManager *fileManager = [NSFileManager defaultManager];
        BOOL hasDownLoad= [fileManager fileExistsAtPath:pathToDownloadTo];
        if (hasDownLoad) {
            self.fileURL = [NSURL fileURLWithPath:pathToDownloadTo];
            QLPreviewController *qlVC = [[QLPreviewController alloc]init];
            qlVC.delegate = self;
            qlVC.dataSource = self;
            //            qlVC.tabBarItem.title = @"预览附件";
            qlVC.navigationItem.hidesBackButton = YES;
            qlVC.qlpTitle = @"预览附件";
            [self.navigationController pushViewController:qlVC animated:YES];
            [WProgressHUD hideAllHUDAnimated:YES];
            //
        }
        else {
            NSURL *targetURL = [NSURL URLWithString:self.workDetailsModel.annex];
            
            NSData *fileData = [[NSData alloc] initWithContentsOfURL:targetURL];
            // Get the path to the App's Documents directory
            NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
            NSString *documentsDirectory = [paths objectAtIndex:0]; // Get documents folder
            [fileData writeToFile:[NSString stringWithFormat:@"%@/%@", documentsDirectory, [targetURL lastPathComponent]] atomically:YES];
            NSURLRequest *request = [NSURLRequest requestWithURL:targetURL];
            [openFileWebView loadRequest:request];
            
        }
    
    NSLog(@"webViewDidFinishLoad");
}

- (void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error
{
    NSLog(@"didFailLoadWithError");
    
    
}

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

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

- (void)previewControllerWillDismiss:(QLPreviewController *)controller {
    NSLog(@"previewControllerWillDismiss");
}

- (void)previewControllerDidDismiss:(QLPreviewController *)controller {
    NSLog(@"previewControllerDidDismiss");
}

- (BOOL)previewController:(QLPreviewController *)controller shouldOpenURL:(NSURL *)url forPreviewItem:(id <QLPreviewItem>)item{
    return YES;
}

- (CGRect)previewController:(QLPreviewController *)controller frameForPreviewItem:(id <QLPreviewItem>)item inSourceView:(UIView * __nullable * __nonnull)view{
    return CGRectZero;
}