iOS WKWebView将文件存储到手机文件中

@interface WebViewController()<UIDocumentInteractionControllerDelegate>
@property (nonatomic, copy) NSString *fileName; //文件名
@property (nonatomic, strong) UIDocumentInteractionController *documentInteractionController;
@end
- (void)webView:(WKWebView *)webView decidePolicyForNavigationResponse:(WKNavigationResponse *)navigationResponse decisionHandler:(void (^)(WKNavigationResponsePolicy))decisionHandler {
    self.fileName = navigationResponse.response.suggestedFilename; //获取文件名称        
    decisionHandler(WKNavigationResponsePolicyAllow);
}
//保存到文件（弹出菜单点击存储到“文件”，即可把文件保存到手机文件中）
-(void)saveToFile{
    NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
    AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:configuration];
    NSURL *URL = [NSURL URLWithString:self.currentURL];
    NSURLRequest *request = [NSURLRequest requestWithURL:URL];
    //判断是否存在
    if([self isFileExist:self.fileName]) {
        NSURL *documentsDirectoryURL = [[NSFileManager defaultManager] URLForDirectory:NSDocumentDirectory inDomain:NSUserDomainMask appropriateForURL:nil create:NO error:nil];
        NSURL *url = [documentsDirectoryURL URLByAppendingPathComponent:self.fileName];
        self.documentInteractionController = [UIDocumentInteractionController
                                                  interactionControllerWithURL:url];
        [self.documentInteractionController setDelegate:self];
        [self.documentInteractionController presentOpenInMenuFromRect:CGRectZero inView:self.view animated:YES];
        [self.documentInteractionController presentPreviewAnimated:YES];
    }else {
        [MBProgressHUD showHUDAddedTo:self.view animated:YES];
        weakify(self);
        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:weakSelf.fileName];
            return url;
        } completionHandler:^(NSURLResponse *response, NSURL *filePath, NSError *error) {
            [MBProgressHUD hideHUDForView:weakSelf.view animated:YES];
            weakSelf.documentInteractionController = [UIDocumentInteractionController
                                                      interactionControllerWithURL:filePath];
            [weakSelf.documentInteractionController setDelegate:weakSelf];
            [weakSelf.documentInteractionController presentOpenInMenuFromRect:CGRectZero inView:weakSelf.view animated:YES];
            [weakSelf.documentInteractionController presentPreviewAnimated:YES];
        }];
        [downloadTask resume];
    }
}