如何创建“下载管理器”,以检测您点击的链接(在UIWebView中)何时文件结尾为“。pdf”,“。png”,“。jpeg”,“。缇“,”。gif“,”。doc“,”。dococ“,”。pt“,”。ptx“,”。xls“和”.xlsx“然后会打开一张UIActionSheet,问你是否想下载或打开。如果选择下载,则会将该文件下载到设备。
该应用程序的另一部分将在UITableView中显示已下载文件的列表,当您点击它们时,它们将显示在UIWebView中,但当然是离线的,因为它们将在本地加载,因为它们将被下载。
请参阅http://itunes.apple.com/gb/app/downloads-lite-downloader/id349275540?mt=8以更好地了解我要做的事情。
这样做的最佳方式是什么?
答案 0 :(得分:31)
使用UiWebView委托中的方法- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType
来确定何时加载资源。
当调用方法时,你只需要解析参数(NSURLRequest *)request
中的URL,如果它是你想要的类型之一则返回NO并继续你的逻辑(UIActionSheet)或如果用户只是返回YES点击了一个HTML文件的简单链接。
有道理吗?
Edit_:为了更好地理解快速代码示例
- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType {
if(navigationType == UIWebViewNavigationTypeLinkClicked) {
NSURL *requestedURL = [request URL];
// ...Check if the URL points to a file you're looking for...
// Then load the file
NSData *fileData = [[NSData alloc] initWithContentsOfURL:requestedURL;
// 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, [requestedURL lastPathComponent]] atomically:YES];
}
}
Edit2_:在我们讨论您在聊天中遇到的问题之后,我已经更新了代码示例:
- (IBAction)saveFile:(id)sender {
// Get the URL of the loaded ressource
NSURL *theRessourcesURL = [[webView request] URL];
NSString *fileExtension = [theRessourcesURL pathExtension];
if ([fileExtension isEqualToString:@"png"] || [fileExtension isEqualToString:@"jpg"]) {
// Get the filename of the loaded ressource form the UIWebView's request URL
NSString *filename = [theRessourcesURL lastPathComponent];
NSLog(@"Filename: %@", filename);
// Get the path to the App's Documents directory
NSString *docPath = [self documentsDirectoryPath];
// Combine the filename and the path to the documents dir into the full path
NSString *pathToDownloadTo = [NSString stringWithFormat:@"%@/%@", docPath, filename];
// Load the file from the remote server
NSData *tmp = [NSData dataWithContentsOfURL:theRessourcesURL];
// Save the loaded data if loaded successfully
if (tmp != nil) {
NSError *error = nil;
// Write the contents of our tmp object into a file
[tmp writeToFile:pathToDownloadTo options:NSDataWritingAtomic error:&error];
if (error != nil) {
NSLog(@"Failed to save the file: %@", [error description]);
} else {
// Display an UIAlertView that shows the users we saved the file :)
UIAlertView *filenameAlert = [[UIAlertView alloc] initWithTitle:@"File saved" message:[NSString stringWithFormat:@"The file %@ has been saved.", filename] delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
[filenameAlert show];
[filenameAlert release];
}
} else {
// File could notbe loaded -> handle errors
}
} else {
// File type not supported
}
}
/**
Just a small helper function
that returns the path to our
Documents directory
**/
- (NSString *)documentsDirectoryPath {
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectoryPath = [paths objectAtIndex:0];
return documentsDirectoryPath;
}